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Clinical and genetic features of paroxysmal kinesigenic dyskinesia in Italian patients
e u r o p e a n j o u r n a l o f p a e d i a t r i c n e u r o l o g y x x x ( 2 0 1 5 ) 1 e6
Official Journal of the European Paediatric Neurology Society
Original Article
Clinical and genetic features of paroxysmal kinesigenic dyskinesia in Italian patients Costanza Lamperti a, Federica Invernizzi a, Roberta Solazzi b, Elena Freri b, Francesco Carella c, Massimo Zeviani d, Federica Zibordi b, Carlo Fusco e, Giovanna Zorzi b, Tiziana Granata b, Barbara Garavaglia a, Nardo Nardocci b,* a
Unit of Molecular Neurogenetics, The Foundation “Carlo Besta” Institute of Neurology IRCCS, Milan, Italy Unit of Neuropediatry, The Foundation “Carlo Besta” Institute of Neurology IRCCS, Milan, Italy c Unit of Movement Disorders, The Foundation “Carlo Besta” Institute of Neurology IRCCS, Milan, Italy d MRC Mitochondrial Biology Unit, Cambridge, UK e Unit of Neuropediatry, Arcispedale Santa Maria Nuova, Reggio Emilia, Italy b
article info
abstract
Article history:
Background: Paroxysmal Kinesigenic Dyskinesia (PKD, OMIM 128200) is the most common
Received 12 December 2014
type of autosomal dominant Paroxysmal Dyskinesias characterized by attacks of dystonia
Received in revised form
and choreoathetosis triggered by sudden movements. Recently PRRT2, encoding proline-rich
24 August 2015
transmembrane protein 2, has been described as the most frequent causative gene for PKD.
Accepted 26 August 2015
Methods: We studied the incidence of PRRT2 mutations in a cohort of 16 PKD patients and their relatives for a total of 39 individuals.
Keywords:
Results: We identify mutations in 10/16 patients and 23 relatives. In 27/33 the mutation was
PRRT2
the c.insC649 p.Arg217Profs*8. In 6 individuals from 3 families we found three new mu-
Paroxysmal kinesigenic dyskinesia
tations: c.insT27 p.Ser9*, c.G967A p.Gly323Arg and c.delCA215_216 p.Thr72Argfs*62. Family
Epilepsy
history was positive in 9 patients. The mean age of onset was 10 years. Attacks lasted from
Dystonia
a few seconds to 1 min and ranged from several per day to some per week, and were
Autosomal dominant
generalised in all patients. The main distinctive features of mutation-negative patients were the sporadic occurrence, the absence of association with epilepsy or EEG abnormalities and the poor response to Carbamazepine or other antiepileptic agents. Conclusions: We report the first cohort of Italian patients mutated in PRRT2 and we confirm that this is the most frequent gene involved in PKD. © 2015 Published by Elsevier Ltd on behalf of European Paediatric Neurology Society.
1.
Introduction
Paroxysmal kinesigenic dyskinesia (PKD, OMIM 128200) is the most common type of Paroxysmal Dyskinesias and is
characterized by recurrent and brief attacks of dystonia and choreoathetosis triggered by sudden movements.1 It is commonly transmitted in an autosomal dominant mode of inheritance.2 The diagnostic criteria for idiopathic PKD include identification of kinesigenic trigger, short duration of
* Corresponding author. E-mail address: [email protected] (N. Nardocci). http://dx.doi.org/10.1016/j.ejpn.2015.08.006 1090-3798/© 2015 Published by Elsevier Ltd on behalf of European Paediatric Neurology Society. Please cite this article in press as: Lamperti C, et al., Clinical and genetic features of paroxysmal kinesigenic dyskinesia in Italian patients, European Journal of Paediatric Neurology (2015), http://dx.doi.org/10.1016/j.ejpn.2015.08.006
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Table 1 e Patients clinical features. Patient
Family
Gender
Age (years)
Family history
Age at onset (years)
Phenomenology of attack
Localisation
Frequency of attacks
1
fam 1
f
19
BFIS
5
Choreoathetosis
Generalized
Several a day
2
fam 2
f
20
PKD
17
Dystonia
Unilateral
Several a week
3
fam 2
m
Adult
PKD
Never
None
None
None
4
fam 3
m
16
PKD
12
Dystonia
Generalized
Several a week
5
fam 3
m
Adult
PKD
12
Dystonia
Generalized
Several a week
6
fam 4
m
11
8
Dystonia
Unilateral
Several a day
7
fam 4
m
Adult
PKD migraine PKD
12
Dystonia
Unilateral
Several a day
8
fam 5
f
19
PKD epilepsy
7 1/2
Dystonia
Generalized
Several a day
9
fam 5
f
17
PKD
11
Choreoathetosis
Generalized
Several a day
epilepsy PKD
Infancy
Choreoathetosis
Generalized
Unknown
10
fam 5
m
Adult
11
fam 6
m
11
PKD
9
Dystonia and chorea
Generalized
Several a day
13
with ballic mov Dystonia with ballic mov
Upper limbs
Monthly
14
Dystonia
Generalized
Several a day
No
No
None
12
fam 6
f
Adult
BFIS PKD BFIS
13
fam 7
m
17
PKD
14
fam 7
f
Adult
PKD
15
fam 8
f
Adult
PKD
10
Dystonia with ballic mov
Unilateral
Several a week
16
fam 9
m
29
PKD
8
Dystonia
Generalized
Several a week
17
fam 9
f
Adult
PKD
Never
No
No
No
18
fam 10
f
34
PKD
12
Dystonia, choreoathetosis
Local, secondary generalized
Several a day
19
fam 10
f
Adult
PKD
Never
No
No
None
20
fam 10
f
Adult
PKD
13
Dystonia
No
Unknown
21
fam 10
f
Adult
PKD
40
Dystonia
Unknown
22
fam 11
f
16
No
2
Choreoathetosis
Local secondary generalized Unilateral
23
fam 12
m
18
No
6 1/2
Dystonia
Local (lower limbs)
Several a day
24
fam 13
f
19
No
2 1/2
Choreoathetosis with ballic mov
Generalized
Several a day
25
fam 14
m
12
Migraine
7 1/2
Choreoathetosis
Generalized
Several a day
26
fam 15
m
12
No
3
Choreoathetosis
Generalized
Several a day
27
fam 16
m
19
No
8
Dystonia
Generalized
Several a day
Several a day
m: male; f: female; BFIS: benign infantile seizures; CBZ: carbamazepine; TPM: topiramate; VPA: valproic acid; N: normal.
Please cite this article in press as: Lamperti C, et al., Clinical and genetic features of paroxysmal kinesigenic dyskinesia in Italian patients, European Journal of Paediatric Neurology (2015), http://dx.doi.org/10.1016/j.ejpn.2015.08.006
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Atypical features of attacks
Presence of aura
Association with other diseases
Treatment/ response
Interictal EEG
Brain MRI
No
No
Epilepsy (BFIS)
CBZ þ
N
N
No
No
Migraine
CBZ þ
N
Cerebellar
No
No
No
None
Not performed
angioma Not performed
No
Feeling
Epilepsy (BFIS)
CBZ þ
N
N
No
No
No
None
(Not performed)
(Not performed)
No
Tickle on shoulder No
No
CBZ þ
N
N
No
None
(Not performed)
(Not performed)
Triggered by tactile stimulus on foot
No
Epilepsy
CBZ þ
Thalamic hyperintensity
No
No
Epilepsy
CBZ þ
Temporal aspecific anomalies at the age of 12 N
No
No
Epilepsy
None
N
N
No
PRRT2 mutation c.insC649 p.Arg217Profs*8 c.insT27
Unknown
p.Ser9* c.insT27 p.Ser9* c.G967A p.Gly323Arg c.G967A p.Gly323Arg
of attacks Asymptomatic
CBZ þ
N
N
BFIS, stereothipies
None
N
N
Feeling
No
CBZ þ
N
(Not performed)
No
No
None
N
(Not performed)
Triggered by
Migraine
None
N
N
No No No
improvise noise
Regression of attacks Spontaneous decrease in frequency Regression of attacks Spontaneous remission of attacks
c.insC649 p.Arg217Profs*8
Regression of attacks
c.insC649
Regression of attacks Spontaneous
N
BFIS, migraine
Fear and discomfort No
Regression
c.delCA 215_216 p.Thr72Argfs*62 c.delCA 215_216 p.Thr72Argfs*62
p.Arg217Profs*8
Triggered by stress, cold No
Follow-up
c.insC649 p.Arg217Profs*8 c.insC649 p.Arg217Profs*8 c.insC649 p.Arg217Profs*8 c.insC649 p.Arg217Profs*8 c.insC649 p.Arg217Profs*8
remission of attacks (only aura)
Spontaneous remission of attacks at 25 Regression of attacks Asymptomatic Spontaneous decrease in frequency At the age of 22 increase in frequency, non response to treatment
Triggered by stress
Discomfort on feet
No
CBZ þ
N
N
c.insC649 p.Arg217Profs*8
No
No
No
None
Not performed
Not performed
Asymptomatic
No
No
Epilepsy
Poor organisation of basal activity
N
No
No
No
l-dopabaclofenCLZ CBZþ None
c.insC649 p.Arg217Profs*8 c.insC649 p.Arg217Profs*8
Not performed
Not performed
c.insC649
Asymptomatic
p.Arg217Profs*8 c.insC649 p.Arg217Profs*8
Regression of attacks
No
No
No
Caþþ
Not performed
Not performed
No
No
No
None
Not performed
Not performed
Rare attacks during
No
No
CBZ
N
N
c.insC649 p.Arg217Profs*8 neg
No
No
CBZ
FCT anomalies in one recording, then N
N
neg
Unknown
Yes
No
VPA CBZ
N
N
neg
Unknown
Paresthesias
Migraine
CBZ
N
N
neg
Unknown
No
No
CBZ
N
N
neg
Unknown
Yes
Migraine
CBZ þ/ TPM þ/
N
N
neg
Unknown
sleep Rare attacks during sleep; spontaneous attacks or triggered by prolonged exercise Rare attacks during sleep; attacks promoted by menstrual period Triggered by physical exercise Rare attacks
Spontaneous remission at the age of 16 Unknown Unknown
during sleep
Please cite this article in press as: Lamperti C, et al., Clinical and genetic features of paroxysmal kinesigenic dyskinesia in Italian patients, European Journal of Paediatric Neurology (2015), http://dx.doi.org/10.1016/j.ejpn.2015.08.006
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attacks (<1 min), no loss of consciousness or pain during attacks, exclusion of other organic diseases and onset age between 1 and 20 years, if no family history for PKD.3 Symptoms usually become less severe with age and affected individuals respond to anticonvulsant drugs such as Carbamazepine.3 However, there have been some reports of patients classified as “atypical PKD” in which attacks were clearly triggered by kinesigenic stimuli, but also spontaneous, or induced by physical exercise.4 Two Chinese groups have identified PRRT2, encoding proline-rich transmembrane protein 2, as a causative gene for PKD.5,6 These findings suggest a predominant role of PRRT2 gene in this paroxysmal movement disorder. Many authors investigated PRRT2 mutations in affected families,7e9 but few reports are available about correlation between the presence of mutations and PKD phenotype.10,11 We report the clinical and genetic features observed in a cohort of 39 individuals from 16 families in order to verify the role of the PRRT2 mutations and the clinical spectrum of PKD.
2.
Patients and methods
All the patients included in the category of Paroxysmal Kinesigenic Dyskinesia (PKD) in the Movement Disorders database at the Fondazione IRCCS Istituto Neurologico Carlo Besta from 1998 to 2013. The study was approved by ethics committee and was performed in accordance with the ethical standards of 1964 declaration of Helsinki. All patients and relatives gave their written informed consent to the study. Patients were included if they fulfilled the criteria for PKD defined by Bruno et al.3: identified kinesigenic trigger for the attacks, short duration of attacks (<1 min), no loss of consciousness or pain during attacks, exclusion of other organic diseases and normal neurologic examination, and age at onset between 1 and 20 year. Clinical and laboratory features were reviewed and all sixteen probands and their relatives underwent a complete clinical neurological examination and in eight out of sixteen patients the attacks were observed directly or using video documentation by neurologists experts in movement disorders. In the remaining individuals the phenomenology of attacks was based on the description by patients themselves or relatives. A description of the attacks and the clinical course of the condition was possible in 18 affected relatives diagnosed with the already decrypted criteria. Patients underwent the following investigations: brain MRI (all pts except one), interictal (all pts) and ictal EEG (two pts). Mental function was evaluated with psychometric standardised tests (Wechsler Intelligence Scale for Children III) in five patients and based on clinical examinations in the remaining. Patients were followed for a period ranging from 5 to 18 years. PRRT2 molecular analysis was performed in all sixteen patients, affected relatives (nineteen individuals) and in first degree relatives of PRRT2 positive patients (four individuals).
3.
Molecular analysis
Total DNA was extracted from peripheral blood sample of patients and relatives, after informed consent. Three coding
exons (2, 3 and 4) were amplified by polymerase chain reaction (PCR) (Exon 2F 50 -GACAGGAATGTGGCCCAATT-30 , Exon 2R 50 -GAAGGAAGGCATGATTACTC-30 , Exon 3F 50 -TCTGGATGACTTTTCCACCT-30 Exon 4R 50 -CTGTAAACAAGGCCGCTCAG30 ). PCR fragments were analyzed by automated nucleotide sequencing using the Big-Dye terminator Ready reaction Kit version 2 on a 3100 Genetic Analyzer Automated Sequencer (Applied Bio Systems).
4.
Results
Demographic, clinical and genetic details of patients and relatives are summarised in Table 1. Family 8 is composed of 13 mutated patients, 8F and 5M, clinical aspect are comparable with index case and for simplicity we insert in the table only the patients. In all the patients both the neurological examination and mental capacities resulted normal. Standard interictal EEG recordings were normal in all patients. In the only two patients performing EEG during the crisis (pts 23 and 25) the ictal EEG recording didn't show any abnormalities during the attack. Brain MRI was normal in all patients. Mutations in PRRT2 gene were identified in ten out of sixteen patients and in twenty-three relatives for a total of 33 mutation positive individuals. In twenty-six out of thirtythree the mutation was the common one c.insC649 (p.Arg217Profs*8). In six individuals from three families we found two never described frame-shift mutations c.insT27 (p.Ser9*) and c.delCA215_216 (p.Thr72Argfs*62) (respectively families 2, 4), and a new missense mutation c.G967A (p.Gly323Arg), not found in the common SNPs database (family 3). The mutations segregate within the families. On the basis of the genetic status we compared the clinical features of the two group of patients. Patients positive for the mutation were five males and five females (m/f 1:1). Family history for PKD was positive in nine patients, comorbid medical disorders, such as epilepsy in two, and migraine in one. Pt 1 had positive family history for benign infantile seizures (BFIS). The age at onset ranged from 5 to 17 years (mean age 10,25 years). Attacks lasted from a few seconds to 1 min and ranged from several per day to some per week; attacks were generalised in all patients with a clear focal onset in one limb in one (pt 18). In one (pt 8) the attacks were triggered by tactile stimuli on foot. The phenomenology of attacks showed a predominance of dystonia (7 out of 10 patients). Five out of ten patients presented association with epilepsy: three showed BIFS before onset of PKD (pts 1, 4 and 11) and two partial or generalised seizures occurring during the course of the disease (pts 8 and 18). All the patients, but one, treated with Carbamazepine (CBZ) presented a total remission of attacks. Patient 15 given the low disability due to symptoms has not been subjected to any drug treatment as well as all the family. Four out of twenty-three mutation-positive relatives didn't report any symptoms while the remaining nineteen reported similar attacks. A complete remission of attacks in adulthood was reported in four individuals. The remaining individuals, including a whole family of thirteen affected, described a
Please cite this article in press as: Lamperti C, et al., Clinical and genetic features of paroxysmal kinesigenic dyskinesia in Italian patients, European Journal of Paediatric Neurology (2015), http://dx.doi.org/10.1016/j.ejpn.2015.08.006
e u r o p e a n j o u r n a l o f p a e d i a t r i c n e u r o l o g y x x x ( 2 0 1 5 ) 1 e6
spontaneous decrease in frequency of attacks during the time. Three mutation-positive symptomatic relatives presented association with epilepsy, including BFIS (pt 9 and pt 12) and generalised seizures in adulthood (pt 10). None of the six negative patients (4 males and 2 females) showed a positive family history for PKD; only one subject had a positive family history for migraine (pt 25). The age at onset ranged from 2 to 8 years (mean age 4,92 years). In two patients association with migraine was reported. The frequency of the attacks was daily; the attacks lasted from a few seconds to 1 min in all. The phenomenology of the attacks was mainly characterized by dystonia or choreoathetosis. Some atypical features were reported: occasional attacks related to physical exercise (pts 23 and 25), promoted by menstrual period (pt 24). One patient (pt 23) also reported rare spontaneous attacks and four (pts 22, 23, 24 and 26) rare attacks occurring during sleep. None of these patients had a response to common antiepileptic drugs such as Carbamazepine, Valproic acid (VPA) and Clonazepam (CLZ). Only one patient (pt 27) presented a partial response (decrease in frequency of attacks) with CBZ and Topiramate (TPM).
5.
Discussion
PRRT2 encodes a 340 amino acid, proline-rich transmembrane protein of unknown function. According to mRNA-expression data (Ensembl) in human tissue, PRRT2 is expressed primarily in the brain and is most highly expressed in the cerebral cortex and basal ganglia (GeneNote). Although the molecular function of PRRT2 is not known, yeast two-hybrid studies suggest that PRRT2 interacts with synaptosomal associated protein 25 kDa (SNAP25) (OMIM 600322). SNAP25 is a presynaptic plasma-membrane-bound protein involved in neurotransmitter release from synaptic vesicles. Its putative binding partner PRRT2 might play a role in this process. Interestingly, the p.Arg217Profs*8 mutation resulted in truncated PRRT2 proteins lacking the transmembrane domain. These truncated proteins cannot anchor to the membrane and may be loss-of-function. Notably, the most reported patients, as well as our cohort, carry the p.Arg217Profs*8 mutation. The exact underlying molecular mechanism as to how these mutations caused PKD, either haploinsufficiency or dominant negative effect, requires further investigation. To enlarge the clinical spectrum of PRRT2 mutations and to investigate the Italian PRRT2 mutations populations we sequence DNA from the probands of sixteen families affected by PKD. All patients fulfilled the criteria for primary PKD. We identified a mutation in PRRT2 gene in 62.5% patients, demonstrating the genetic heterogeneity of PKD. The common c.insC649 mutation was identified in the majority of patients. In our series, patients carrying the three new mutations, did not differ in any clinical aspect and no correlation between phenotype and genotype can be suggested. A minority (4/13) of individuals carrying the most common c.insC649 mutation were asymptomatic, confirming the incomplete penetrance of the mutation.10 As described we confirmed a variability in the clinical manifestations associate with PRRT2. This is evident not only in patients carrying the same mutations but either within the same family, suggesting in our cohort a anticipations effect.
5
Mutation positive patients in our series presented the typical features of the disease, including proprioceptive stimuli as trigger of attacks, which is unusual, but already described in literature. It's worth noting that one patient (pt 21) reported the onset of attacks at 40 years: such a late onset in idiopathic PKD has been reported only once in the literature.12 In our series we were not able to identify any difference between positive and negative PRRT2 mutations patients regarding the phenomenology, duration nor frequency of attacks. Recent reports suggest an earlier onset and a better response to treatment in mutation positive patients.10,11 Our series supports the good response to treatment in mutationpositive patients although the mean age at onset was higher in comparison with mutation-negative patients. Only mutation-negative patients showed atypical features, as suggested by a recent report.4 The main distinctive features of mutation-negative patients were the sporadic occurrence, the absence of association with epilepsy or EEG abnormalities and the poor response to Carbamazepine or other antiepileptic agents. The absence of cerebellar features during the attacks and the type of triggers that did not include, for example, prolonged exercise or starvation, made KCNA1 and SLC2A1 mutations unlikely. Family history for PKD and epilepsy resulted only in PRRT2 positive patients, as association with seizures, including Benign Infantile Seizures (BIS) as described.13 All PRRT2 mutation positive patients who started the treatment with low-dose Carbamazepine presented a good response with a complete remission of attacks confirming other observation10 while in all the PRRT2 negative patients efficacy of Carbamazepine or other antiepileptic drugs was partial or absent. The clinical follow-up and the informations reported by the patients' relatives allowed a description of the clinical course of the disease: as already described, there is a spontaneous clinical amelioration in adulthood, but only four out of 33 mutated patients in our series presented a complete spontaneous remission of attacks, while 14 presented a decrease in frequency. In conclusion we report the first Italian cohort of PKD patients and we confirm that PRRT2 is the most frequent gene involved in PKD.
Conflict of interest None.
Author contributions C.L.; F.I. equally contributed to this work. C.L.; M.Z.; R.S.; E.F.; F.C.; F.Z.; C.F.; G.Z.; T.G. clinical work. F.I.; B.G. molecular studies. C.L.; F.I.; N.N. write the paper. M.Z.; B.G.; N.N. data discussion.
Acknowledgement We thanks for the support the Pierfranco and Luisa Mariani Foundation Italy, the Telethon Network of Genetic
Please cite this article in press as: Lamperti C, et al., Clinical and genetic features of paroxysmal kinesigenic dyskinesia in Italian patients, European Journal of Paediatric Neurology (2015), http://dx.doi.org/10.1016/j.ejpn.2015.08.006
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Biobanks (Project No.GTB12001) and of the Eurobiobank Network.
references
1. Jankovic J, Demirkiran M. Classification of paroxysmal dyskinesias and ataxias. Adv Neurol 2002;89:387e400. 2. Nagamitsu S, Matsuishi T, Hashimoto K, et al. Multicenter study of paroxysmal dyskinesias in Japan-clinical and pedigree analysis. Mov Disord 1999 Jul;14(4):658e63. 3. Bruno MK, Hallett M, Gwinn-Hardy K, et al. Clinical evaluation of idiopathic paroxysmal kinesigenic dyskinesia: new diagnostic criteria. Neurology 2004;63:2280e7. 4. Pourfar MH, Guerrini R, Parain D, Frucht SJ. Classification conundrums in paroxysmal dyskinesias: a new subtype or variations on classic themes? Mov Disord 2005 Aug;20(8):1047e51. 5. Chen WJ, Lin Y, Xiong ZQ, et al. Exome sequencing identifies truncating mutations in PRRT2 that cause paroxysmal kinesigenic dyskinesia. Nat Genet 2011;43:1252e5. 6. Li J, Zhu X, Wang X, et al. Targeted genomic sequencing identifies PRRT2 mutations as a cause of paroxysmal kinesigenic choreoathetosis. J Med Genet 2012;49:76e8.
7. Liu Q, Qi Z, Wan XH, et al. Mutations in PRRT2 result in paroxysmal dyskinesias with marked variability in clinical expression. J Med Genet 2012 Feb;49(2):79e82. 8. Heron SE, Dibbens LM. Role of PRRT2 in common paroxysmal neurological disorders: a gene with remarkable pleiotropy. J Med Genet 2013 Mar;50(3):133e9. 9. Guerrini R, Mink JW. Paroxysmal disorders associated with PRRT2 mutations shake up expectations on ion channel genes. Neurology 2012;79:1e3. 10. Li HF, Chen WJ, Ni W, et al. PRRT2 mutation correlated with phenotype of paroxysmal kinesigenic dyskinesia and drug response. Neurology 2013;80:1534e5. 11. Tan LC, Methawasin K, Teng EW, et al. Clinico-genetic comparisons of paroxysmal kinesigenic dyskinesia patients with and without PRRT2 mutations. Eur J Neurol 2014, Apr;21(4):674e8. 12. Iwasaki Y, Nakamura T, Hamada K. Late-onset of idiopathic paroxysmal kinesigenic choreoathetosis: a case report. Rinsho Shinkeigaku 2004 Jun;44(6):365e8. 13. Schubert J, Paravidino R, Becker F, Berger A, et al. PRRT2 mutations are the major cause of benign familial infantile seizures. Hum Mutat 2012, Oct;33(10):1439e43.
Please cite this article in press as: Lamperti C, et al., Clinical and genetic features of paroxysmal kinesigenic dyskinesia in Italian patients, European Journal of Paediatric Neurology (2015), http://dx.doi.org/10.1016/j.ejpn.2015.08.006
Official Journal of the European Paediatric Neurology Society
Original Article
Clinical and genetic features of paroxysmal kinesigenic dyskinesia in Italian patients Costanza Lamperti a, Federica Invernizzi a, Roberta Solazzi b, Elena Freri b, Francesco Carella c, Massimo Zeviani d, Federica Zibordi b, Carlo Fusco e, Giovanna Zorzi b, Tiziana Granata b, Barbara Garavaglia a, Nardo Nardocci b,* a
Unit of Molecular Neurogenetics, The Foundation “Carlo Besta” Institute of Neurology IRCCS, Milan, Italy Unit of Neuropediatry, The Foundation “Carlo Besta” Institute of Neurology IRCCS, Milan, Italy c Unit of Movement Disorders, The Foundation “Carlo Besta” Institute of Neurology IRCCS, Milan, Italy d MRC Mitochondrial Biology Unit, Cambridge, UK e Unit of Neuropediatry, Arcispedale Santa Maria Nuova, Reggio Emilia, Italy b
article info
abstract
Article history:
Background: Paroxysmal Kinesigenic Dyskinesia (PKD, OMIM 128200) is the most common
Received 12 December 2014
type of autosomal dominant Paroxysmal Dyskinesias characterized by attacks of dystonia
Received in revised form
and choreoathetosis triggered by sudden movements. Recently PRRT2, encoding proline-rich
24 August 2015
transmembrane protein 2, has been described as the most frequent causative gene for PKD.
Accepted 26 August 2015
Methods: We studied the incidence of PRRT2 mutations in a cohort of 16 PKD patients and their relatives for a total of 39 individuals.
Keywords:
Results: We identify mutations in 10/16 patients and 23 relatives. In 27/33 the mutation was
PRRT2
the c.insC649 p.Arg217Profs*8. In 6 individuals from 3 families we found three new mu-
Paroxysmal kinesigenic dyskinesia
tations: c.insT27 p.Ser9*, c.G967A p.Gly323Arg and c.delCA215_216 p.Thr72Argfs*62. Family
Epilepsy
history was positive in 9 patients. The mean age of onset was 10 years. Attacks lasted from
Dystonia
a few seconds to 1 min and ranged from several per day to some per week, and were
Autosomal dominant
generalised in all patients. The main distinctive features of mutation-negative patients were the sporadic occurrence, the absence of association with epilepsy or EEG abnormalities and the poor response to Carbamazepine or other antiepileptic agents. Conclusions: We report the first cohort of Italian patients mutated in PRRT2 and we confirm that this is the most frequent gene involved in PKD. © 2015 Published by Elsevier Ltd on behalf of European Paediatric Neurology Society.
1.
Introduction
Paroxysmal kinesigenic dyskinesia (PKD, OMIM 128200) is the most common type of Paroxysmal Dyskinesias and is
characterized by recurrent and brief attacks of dystonia and choreoathetosis triggered by sudden movements.1 It is commonly transmitted in an autosomal dominant mode of inheritance.2 The diagnostic criteria for idiopathic PKD include identification of kinesigenic trigger, short duration of
* Corresponding author. E-mail address: [email protected] (N. Nardocci). http://dx.doi.org/10.1016/j.ejpn.2015.08.006 1090-3798/© 2015 Published by Elsevier Ltd on behalf of European Paediatric Neurology Society. Please cite this article in press as: Lamperti C, et al., Clinical and genetic features of paroxysmal kinesigenic dyskinesia in Italian patients, European Journal of Paediatric Neurology (2015), http://dx.doi.org/10.1016/j.ejpn.2015.08.006
2
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Table 1 e Patients clinical features. Patient
Family
Gender
Age (years)
Family history
Age at onset (years)
Phenomenology of attack
Localisation
Frequency of attacks
1
fam 1
f
19
BFIS
5
Choreoathetosis
Generalized
Several a day
2
fam 2
f
20
PKD
17
Dystonia
Unilateral
Several a week
3
fam 2
m
Adult
PKD
Never
None
None
None
4
fam 3
m
16
PKD
12
Dystonia
Generalized
Several a week
5
fam 3
m
Adult
PKD
12
Dystonia
Generalized
Several a week
6
fam 4
m
11
8
Dystonia
Unilateral
Several a day
7
fam 4
m
Adult
PKD migraine PKD
12
Dystonia
Unilateral
Several a day
8
fam 5
f
19
PKD epilepsy
7 1/2
Dystonia
Generalized
Several a day
9
fam 5
f
17
PKD
11
Choreoathetosis
Generalized
Several a day
epilepsy PKD
Infancy
Choreoathetosis
Generalized
Unknown
10
fam 5
m
Adult
11
fam 6
m
11
PKD
9
Dystonia and chorea
Generalized
Several a day
13
with ballic mov Dystonia with ballic mov
Upper limbs
Monthly
14
Dystonia
Generalized
Several a day
No
No
None
12
fam 6
f
Adult
BFIS PKD BFIS
13
fam 7
m
17
PKD
14
fam 7
f
Adult
PKD
15
fam 8
f
Adult
PKD
10
Dystonia with ballic mov
Unilateral
Several a week
16
fam 9
m
29
PKD
8
Dystonia
Generalized
Several a week
17
fam 9
f
Adult
PKD
Never
No
No
No
18
fam 10
f
34
PKD
12
Dystonia, choreoathetosis
Local, secondary generalized
Several a day
19
fam 10
f
Adult
PKD
Never
No
No
None
20
fam 10
f
Adult
PKD
13
Dystonia
No
Unknown
21
fam 10
f
Adult
PKD
40
Dystonia
Unknown
22
fam 11
f
16
No
2
Choreoathetosis
Local secondary generalized Unilateral
23
fam 12
m
18
No
6 1/2
Dystonia
Local (lower limbs)
Several a day
24
fam 13
f
19
No
2 1/2
Choreoathetosis with ballic mov
Generalized
Several a day
25
fam 14
m
12
Migraine
7 1/2
Choreoathetosis
Generalized
Several a day
26
fam 15
m
12
No
3
Choreoathetosis
Generalized
Several a day
27
fam 16
m
19
No
8
Dystonia
Generalized
Several a day
Several a day
m: male; f: female; BFIS: benign infantile seizures; CBZ: carbamazepine; TPM: topiramate; VPA: valproic acid; N: normal.
Please cite this article in press as: Lamperti C, et al., Clinical and genetic features of paroxysmal kinesigenic dyskinesia in Italian patients, European Journal of Paediatric Neurology (2015), http://dx.doi.org/10.1016/j.ejpn.2015.08.006
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Atypical features of attacks
Presence of aura
Association with other diseases
Treatment/ response
Interictal EEG
Brain MRI
No
No
Epilepsy (BFIS)
CBZ þ
N
N
No
No
Migraine
CBZ þ
N
Cerebellar
No
No
No
None
Not performed
angioma Not performed
No
Feeling
Epilepsy (BFIS)
CBZ þ
N
N
No
No
No
None
(Not performed)
(Not performed)
No
Tickle on shoulder No
No
CBZ þ
N
N
No
None
(Not performed)
(Not performed)
Triggered by tactile stimulus on foot
No
Epilepsy
CBZ þ
Thalamic hyperintensity
No
No
Epilepsy
CBZ þ
Temporal aspecific anomalies at the age of 12 N
No
No
Epilepsy
None
N
N
No
PRRT2 mutation c.insC649 p.Arg217Profs*8 c.insT27
Unknown
p.Ser9* c.insT27 p.Ser9* c.G967A p.Gly323Arg c.G967A p.Gly323Arg
of attacks Asymptomatic
CBZ þ
N
N
BFIS, stereothipies
None
N
N
Feeling
No
CBZ þ
N
(Not performed)
No
No
None
N
(Not performed)
Triggered by
Migraine
None
N
N
No No No
improvise noise
Regression of attacks Spontaneous decrease in frequency Regression of attacks Spontaneous remission of attacks
c.insC649 p.Arg217Profs*8
Regression of attacks
c.insC649
Regression of attacks Spontaneous
N
BFIS, migraine
Fear and discomfort No
Regression
c.delCA 215_216 p.Thr72Argfs*62 c.delCA 215_216 p.Thr72Argfs*62
p.Arg217Profs*8
Triggered by stress, cold No
Follow-up
c.insC649 p.Arg217Profs*8 c.insC649 p.Arg217Profs*8 c.insC649 p.Arg217Profs*8 c.insC649 p.Arg217Profs*8 c.insC649 p.Arg217Profs*8
remission of attacks (only aura)
Spontaneous remission of attacks at 25 Regression of attacks Asymptomatic Spontaneous decrease in frequency At the age of 22 increase in frequency, non response to treatment
Triggered by stress
Discomfort on feet
No
CBZ þ
N
N
c.insC649 p.Arg217Profs*8
No
No
No
None
Not performed
Not performed
Asymptomatic
No
No
Epilepsy
Poor organisation of basal activity
N
No
No
No
l-dopabaclofenCLZ CBZþ None
c.insC649 p.Arg217Profs*8 c.insC649 p.Arg217Profs*8
Not performed
Not performed
c.insC649
Asymptomatic
p.Arg217Profs*8 c.insC649 p.Arg217Profs*8
Regression of attacks
No
No
No
Caþþ
Not performed
Not performed
No
No
No
None
Not performed
Not performed
Rare attacks during
No
No
CBZ
N
N
c.insC649 p.Arg217Profs*8 neg
No
No
CBZ
FCT anomalies in one recording, then N
N
neg
Unknown
Yes
No
VPA CBZ
N
N
neg
Unknown
Paresthesias
Migraine
CBZ
N
N
neg
Unknown
No
No
CBZ
N
N
neg
Unknown
Yes
Migraine
CBZ þ/ TPM þ/
N
N
neg
Unknown
sleep Rare attacks during sleep; spontaneous attacks or triggered by prolonged exercise Rare attacks during sleep; attacks promoted by menstrual period Triggered by physical exercise Rare attacks
Spontaneous remission at the age of 16 Unknown Unknown
during sleep
Please cite this article in press as: Lamperti C, et al., Clinical and genetic features of paroxysmal kinesigenic dyskinesia in Italian patients, European Journal of Paediatric Neurology (2015), http://dx.doi.org/10.1016/j.ejpn.2015.08.006
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attacks (<1 min), no loss of consciousness or pain during attacks, exclusion of other organic diseases and onset age between 1 and 20 years, if no family history for PKD.3 Symptoms usually become less severe with age and affected individuals respond to anticonvulsant drugs such as Carbamazepine.3 However, there have been some reports of patients classified as “atypical PKD” in which attacks were clearly triggered by kinesigenic stimuli, but also spontaneous, or induced by physical exercise.4 Two Chinese groups have identified PRRT2, encoding proline-rich transmembrane protein 2, as a causative gene for PKD.5,6 These findings suggest a predominant role of PRRT2 gene in this paroxysmal movement disorder. Many authors investigated PRRT2 mutations in affected families,7e9 but few reports are available about correlation between the presence of mutations and PKD phenotype.10,11 We report the clinical and genetic features observed in a cohort of 39 individuals from 16 families in order to verify the role of the PRRT2 mutations and the clinical spectrum of PKD.
2.
Patients and methods
All the patients included in the category of Paroxysmal Kinesigenic Dyskinesia (PKD) in the Movement Disorders database at the Fondazione IRCCS Istituto Neurologico Carlo Besta from 1998 to 2013. The study was approved by ethics committee and was performed in accordance with the ethical standards of 1964 declaration of Helsinki. All patients and relatives gave their written informed consent to the study. Patients were included if they fulfilled the criteria for PKD defined by Bruno et al.3: identified kinesigenic trigger for the attacks, short duration of attacks (<1 min), no loss of consciousness or pain during attacks, exclusion of other organic diseases and normal neurologic examination, and age at onset between 1 and 20 year. Clinical and laboratory features were reviewed and all sixteen probands and their relatives underwent a complete clinical neurological examination and in eight out of sixteen patients the attacks were observed directly or using video documentation by neurologists experts in movement disorders. In the remaining individuals the phenomenology of attacks was based on the description by patients themselves or relatives. A description of the attacks and the clinical course of the condition was possible in 18 affected relatives diagnosed with the already decrypted criteria. Patients underwent the following investigations: brain MRI (all pts except one), interictal (all pts) and ictal EEG (two pts). Mental function was evaluated with psychometric standardised tests (Wechsler Intelligence Scale for Children III) in five patients and based on clinical examinations in the remaining. Patients were followed for a period ranging from 5 to 18 years. PRRT2 molecular analysis was performed in all sixteen patients, affected relatives (nineteen individuals) and in first degree relatives of PRRT2 positive patients (four individuals).
3.
Molecular analysis
Total DNA was extracted from peripheral blood sample of patients and relatives, after informed consent. Three coding
exons (2, 3 and 4) were amplified by polymerase chain reaction (PCR) (Exon 2F 50 -GACAGGAATGTGGCCCAATT-30 , Exon 2R 50 -GAAGGAAGGCATGATTACTC-30 , Exon 3F 50 -TCTGGATGACTTTTCCACCT-30 Exon 4R 50 -CTGTAAACAAGGCCGCTCAG30 ). PCR fragments were analyzed by automated nucleotide sequencing using the Big-Dye terminator Ready reaction Kit version 2 on a 3100 Genetic Analyzer Automated Sequencer (Applied Bio Systems).
4.
Results
Demographic, clinical and genetic details of patients and relatives are summarised in Table 1. Family 8 is composed of 13 mutated patients, 8F and 5M, clinical aspect are comparable with index case and for simplicity we insert in the table only the patients. In all the patients both the neurological examination and mental capacities resulted normal. Standard interictal EEG recordings were normal in all patients. In the only two patients performing EEG during the crisis (pts 23 and 25) the ictal EEG recording didn't show any abnormalities during the attack. Brain MRI was normal in all patients. Mutations in PRRT2 gene were identified in ten out of sixteen patients and in twenty-three relatives for a total of 33 mutation positive individuals. In twenty-six out of thirtythree the mutation was the common one c.insC649 (p.Arg217Profs*8). In six individuals from three families we found two never described frame-shift mutations c.insT27 (p.Ser9*) and c.delCA215_216 (p.Thr72Argfs*62) (respectively families 2, 4), and a new missense mutation c.G967A (p.Gly323Arg), not found in the common SNPs database (family 3). The mutations segregate within the families. On the basis of the genetic status we compared the clinical features of the two group of patients. Patients positive for the mutation were five males and five females (m/f 1:1). Family history for PKD was positive in nine patients, comorbid medical disorders, such as epilepsy in two, and migraine in one. Pt 1 had positive family history for benign infantile seizures (BFIS). The age at onset ranged from 5 to 17 years (mean age 10,25 years). Attacks lasted from a few seconds to 1 min and ranged from several per day to some per week; attacks were generalised in all patients with a clear focal onset in one limb in one (pt 18). In one (pt 8) the attacks were triggered by tactile stimuli on foot. The phenomenology of attacks showed a predominance of dystonia (7 out of 10 patients). Five out of ten patients presented association with epilepsy: three showed BIFS before onset of PKD (pts 1, 4 and 11) and two partial or generalised seizures occurring during the course of the disease (pts 8 and 18). All the patients, but one, treated with Carbamazepine (CBZ) presented a total remission of attacks. Patient 15 given the low disability due to symptoms has not been subjected to any drug treatment as well as all the family. Four out of twenty-three mutation-positive relatives didn't report any symptoms while the remaining nineteen reported similar attacks. A complete remission of attacks in adulthood was reported in four individuals. The remaining individuals, including a whole family of thirteen affected, described a
Please cite this article in press as: Lamperti C, et al., Clinical and genetic features of paroxysmal kinesigenic dyskinesia in Italian patients, European Journal of Paediatric Neurology (2015), http://dx.doi.org/10.1016/j.ejpn.2015.08.006
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spontaneous decrease in frequency of attacks during the time. Three mutation-positive symptomatic relatives presented association with epilepsy, including BFIS (pt 9 and pt 12) and generalised seizures in adulthood (pt 10). None of the six negative patients (4 males and 2 females) showed a positive family history for PKD; only one subject had a positive family history for migraine (pt 25). The age at onset ranged from 2 to 8 years (mean age 4,92 years). In two patients association with migraine was reported. The frequency of the attacks was daily; the attacks lasted from a few seconds to 1 min in all. The phenomenology of the attacks was mainly characterized by dystonia or choreoathetosis. Some atypical features were reported: occasional attacks related to physical exercise (pts 23 and 25), promoted by menstrual period (pt 24). One patient (pt 23) also reported rare spontaneous attacks and four (pts 22, 23, 24 and 26) rare attacks occurring during sleep. None of these patients had a response to common antiepileptic drugs such as Carbamazepine, Valproic acid (VPA) and Clonazepam (CLZ). Only one patient (pt 27) presented a partial response (decrease in frequency of attacks) with CBZ and Topiramate (TPM).
5.
Discussion
PRRT2 encodes a 340 amino acid, proline-rich transmembrane protein of unknown function. According to mRNA-expression data (Ensembl) in human tissue, PRRT2 is expressed primarily in the brain and is most highly expressed in the cerebral cortex and basal ganglia (GeneNote). Although the molecular function of PRRT2 is not known, yeast two-hybrid studies suggest that PRRT2 interacts with synaptosomal associated protein 25 kDa (SNAP25) (OMIM 600322). SNAP25 is a presynaptic plasma-membrane-bound protein involved in neurotransmitter release from synaptic vesicles. Its putative binding partner PRRT2 might play a role in this process. Interestingly, the p.Arg217Profs*8 mutation resulted in truncated PRRT2 proteins lacking the transmembrane domain. These truncated proteins cannot anchor to the membrane and may be loss-of-function. Notably, the most reported patients, as well as our cohort, carry the p.Arg217Profs*8 mutation. The exact underlying molecular mechanism as to how these mutations caused PKD, either haploinsufficiency or dominant negative effect, requires further investigation. To enlarge the clinical spectrum of PRRT2 mutations and to investigate the Italian PRRT2 mutations populations we sequence DNA from the probands of sixteen families affected by PKD. All patients fulfilled the criteria for primary PKD. We identified a mutation in PRRT2 gene in 62.5% patients, demonstrating the genetic heterogeneity of PKD. The common c.insC649 mutation was identified in the majority of patients. In our series, patients carrying the three new mutations, did not differ in any clinical aspect and no correlation between phenotype and genotype can be suggested. A minority (4/13) of individuals carrying the most common c.insC649 mutation were asymptomatic, confirming the incomplete penetrance of the mutation.10 As described we confirmed a variability in the clinical manifestations associate with PRRT2. This is evident not only in patients carrying the same mutations but either within the same family, suggesting in our cohort a anticipations effect.
5
Mutation positive patients in our series presented the typical features of the disease, including proprioceptive stimuli as trigger of attacks, which is unusual, but already described in literature. It's worth noting that one patient (pt 21) reported the onset of attacks at 40 years: such a late onset in idiopathic PKD has been reported only once in the literature.12 In our series we were not able to identify any difference between positive and negative PRRT2 mutations patients regarding the phenomenology, duration nor frequency of attacks. Recent reports suggest an earlier onset and a better response to treatment in mutation positive patients.10,11 Our series supports the good response to treatment in mutationpositive patients although the mean age at onset was higher in comparison with mutation-negative patients. Only mutation-negative patients showed atypical features, as suggested by a recent report.4 The main distinctive features of mutation-negative patients were the sporadic occurrence, the absence of association with epilepsy or EEG abnormalities and the poor response to Carbamazepine or other antiepileptic agents. The absence of cerebellar features during the attacks and the type of triggers that did not include, for example, prolonged exercise or starvation, made KCNA1 and SLC2A1 mutations unlikely. Family history for PKD and epilepsy resulted only in PRRT2 positive patients, as association with seizures, including Benign Infantile Seizures (BIS) as described.13 All PRRT2 mutation positive patients who started the treatment with low-dose Carbamazepine presented a good response with a complete remission of attacks confirming other observation10 while in all the PRRT2 negative patients efficacy of Carbamazepine or other antiepileptic drugs was partial or absent. The clinical follow-up and the informations reported by the patients' relatives allowed a description of the clinical course of the disease: as already described, there is a spontaneous clinical amelioration in adulthood, but only four out of 33 mutated patients in our series presented a complete spontaneous remission of attacks, while 14 presented a decrease in frequency. In conclusion we report the first Italian cohort of PKD patients and we confirm that PRRT2 is the most frequent gene involved in PKD.
Conflict of interest None.
Author contributions C.L.; F.I. equally contributed to this work. C.L.; M.Z.; R.S.; E.F.; F.C.; F.Z.; C.F.; G.Z.; T.G. clinical work. F.I.; B.G. molecular studies. C.L.; F.I.; N.N. write the paper. M.Z.; B.G.; N.N. data discussion.
Acknowledgement We thanks for the support the Pierfranco and Luisa Mariani Foundation Italy, the Telethon Network of Genetic
Please cite this article in press as: Lamperti C, et al., Clinical and genetic features of paroxysmal kinesigenic dyskinesia in Italian patients, European Journal of Paediatric Neurology (2015), http://dx.doi.org/10.1016/j.ejpn.2015.08.006
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Biobanks (Project No.GTB12001) and of the Eurobiobank Network.
references
1. Jankovic J, Demirkiran M. Classification of paroxysmal dyskinesias and ataxias. Adv Neurol 2002;89:387e400. 2. Nagamitsu S, Matsuishi T, Hashimoto K, et al. Multicenter study of paroxysmal dyskinesias in Japan-clinical and pedigree analysis. Mov Disord 1999 Jul;14(4):658e63. 3. Bruno MK, Hallett M, Gwinn-Hardy K, et al. Clinical evaluation of idiopathic paroxysmal kinesigenic dyskinesia: new diagnostic criteria. Neurology 2004;63:2280e7. 4. Pourfar MH, Guerrini R, Parain D, Frucht SJ. Classification conundrums in paroxysmal dyskinesias: a new subtype or variations on classic themes? Mov Disord 2005 Aug;20(8):1047e51. 5. Chen WJ, Lin Y, Xiong ZQ, et al. Exome sequencing identifies truncating mutations in PRRT2 that cause paroxysmal kinesigenic dyskinesia. Nat Genet 2011;43:1252e5. 6. Li J, Zhu X, Wang X, et al. Targeted genomic sequencing identifies PRRT2 mutations as a cause of paroxysmal kinesigenic choreoathetosis. J Med Genet 2012;49:76e8.
7. Liu Q, Qi Z, Wan XH, et al. Mutations in PRRT2 result in paroxysmal dyskinesias with marked variability in clinical expression. J Med Genet 2012 Feb;49(2):79e82. 8. Heron SE, Dibbens LM. Role of PRRT2 in common paroxysmal neurological disorders: a gene with remarkable pleiotropy. J Med Genet 2013 Mar;50(3):133e9. 9. Guerrini R, Mink JW. Paroxysmal disorders associated with PRRT2 mutations shake up expectations on ion channel genes. Neurology 2012;79:1e3. 10. Li HF, Chen WJ, Ni W, et al. PRRT2 mutation correlated with phenotype of paroxysmal kinesigenic dyskinesia and drug response. Neurology 2013;80:1534e5. 11. Tan LC, Methawasin K, Teng EW, et al. Clinico-genetic comparisons of paroxysmal kinesigenic dyskinesia patients with and without PRRT2 mutations. Eur J Neurol 2014, Apr;21(4):674e8. 12. Iwasaki Y, Nakamura T, Hamada K. Late-onset of idiopathic paroxysmal kinesigenic choreoathetosis: a case report. Rinsho Shinkeigaku 2004 Jun;44(6):365e8. 13. Schubert J, Paravidino R, Becker F, Berger A, et al. PRRT2 mutations are the major cause of benign familial infantile seizures. Hum Mutat 2012, Oct;33(10):1439e43.
Please cite this article in press as: Lamperti C, et al., Clinical and genetic features of paroxysmal kinesigenic dyskinesia in Italian patients, European Journal of Paediatric Neurology (2015), http://dx.doi.org/10.1016/j.ejpn.2015.08.006