Cognitive development in females with PCDH19 gene-related epilepsy

Epilepsy & Behavior 42 (2015) 36–40

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Cognitive development in females with PCDH19 gene-related epilepsy Simona Cappelletti a,1, Nicola Specchio b,⁎,1, Romina Moavero c, Alessandra Terracciano d, Marina Trivisano b, Giuseppe Pontrelli e, Simonetta Gentile a, Federico Vigevano b, Raffaella Cusmai b a

Unit of Clinical Psychology, Department of Neuroscience, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy Division of Neurology, Department of Neuroscience, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy Systems Medicine Department, Child Neurology Unit, Tor Vergata University of Rome, Italy d Unit of Molecular Medicine for Neuromuscular and Neurodegenerative Diseases, Department of Neuroscience, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy e “Amaducci” Neurology Unit, Department of Neuroscience, University of Bari, Bari, Italy b c

a r t i c l e

i n f o

Article history: Received 8 January 2014 Revised 27 September 2014 Accepted 14 October 2014 Available online xxxx Keywords: PCDH19 gene Epilepsy Cognitive and behavioral profile

a b s t r a c t Mutations in the PCDH19 gene are now recognized to cause epilepsy in females and are claiming increasing interest in the scientific world. Clinical features and seizure semiology have been described as heterogeneous. Intellectual disability might be present, ranging from mild to severe; behavioral and psychiatric problems are a common feature of the disorder, including aggressiveness, depressed mood, and psychotic traits. The purpose of our study was to describe the cognitive development in 11 girls with a de novo mutation in PCDH19 and early-onset epilepsy. Six patients had average mental development or mild intellectual disability regardless of persistence of seizures in clusters. Five patients presented moderate or severe intellectual disability and autistic features. In younger patients, we found that despite an average developmental quotient, they all presented a delay of expressive language acquisition and lower scores at follow-up testing completed at older ages, underlining that subtle dysfunctions might be present. Larger cohort and long-term follow-up might be useful in defining cognitive features and in improving the care of patients with PCDH19. © 2014 Elsevier Inc. All rights reserved.

1. Introduction Protocadherins form a subfamily of calcium-dependent cell–cell adhesion molecules in the cadherin superfamily. Protocadherin 19 (PCDH19), which is located at Xq22.1, belongs to the delta-2 protocadherin subclass of the cadherin superfamily [1]. Mutations in the PCDH19 gene are now recognized to cause epilepsy in females and are claiming increasing interest in the scientific world. Protocadherin 19 mutation is an X-linked disorder with an unusual expression pattern since the phenotype is restricted to females; carrier males are apparently unaffected. Clinical features and seizure semiology have been described as heterogeneous. Seizures have been reported to be in clusters, often precipitated by fever; they can be focal or generalized, usually polymorphic, so patients may present with tonic–clonic, tonic, absence, myoclonic, and atonic seizures. In the last few years, electroclinical features have been clarified. A recent paper analyzed the main features of epilepsy at its

⁎ Corresponding author at: Division of Neurology, Bambino Gesù Children's Hospital, IRCCS, P.zza S. Onofrio 4, 00165 Rome, Italy. Tel.: +39 0668592645; fax: + 39 0668592463. E-mail address: [email protected] (N. Specchio). 1 Both authors equally contributed to this manuscript.

http://dx.doi.org/10.1016/j.yebeh.2014.10.019 1525-5050/© 2014 Elsevier Inc. All rights reserved.

onset, finding a high prevalence of affective symptoms, such as fearful screaming, during the ictal phase [2]. Intellectual disability might be present, ranging from mild to severe; behavioral and psychiatric problems are a common feature of the disorder, including aggressiveness, depressed mood, and psychotic traits [2,3]. Clinical course is usually characterized by persistence of seizures, with clusters decreasing over time, as well as interictal epileptiform abnormalities. A recent review [4] summarized the cognitive and behavioral findings of a total of 110 patients reported up to 2011 (109 females, 1 male). Intellectual disability and behavioral problems occurred in 75.4% and 55.4% of cases, respectively; 44.2% of the patients had been diagnosed with autism spectrum disorders. Cognitive evaluations of girls with PCDH19 mutations are poorly reported. The aim of our study was to describe the cognitive profile in 11 girls with PCDH19-related epilepsy. In the previous reports regarding neuropsychological and psychiatric features in patients with PCDH19, data have been expressed mainly following a clinical observation, and standardized assessments are lacking during the follow-up. In our series, all patients have been followed up with standardized cognitive evaluation and have been screened for behavioral problems; these assessments were conducted for clinical and research purposes. Moreover, in the youngest patients, a neurocognitive

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m: months; y: years; FSsG: focal seizure secondary generalization; TCS: tonic–clonic seizures; SE; status epilepticus; Y: yes; N: no; T: temporal; C: central; P: parietal; F: frontal.

Transient F spikes Diffuse theta Y — since 35 y Bilateral F–T GS + FS Y N N 10 11

FSsG, TCS, staring, head and eye deviation

8 3 7

FSsG, TCS, staring, atonic, clonic, head and eye deviation FSsG, TCS, hypomotor, staring, cyanosis, automatisms FSsG, TCS, cyanosis, apnea, desaturation

Y (1) N Y (8)

Y N N

Y Y Y

FSsG FSsG GS + FS

Left T or FT Bilateral T Right/left FT

N — 2 clusters/y N — 3 clusters/y Y — since 16 y

Diffuse or bilateral C theta Bilateral F spikes Bilateral FT spikes Normal Y — since 9 y, 10 m Y (4)

Y

N

GS + FS

Right/left CT/C

Diffuse theta Normal Normal CP theta Asynchronous T delta Normal N Y Y N Y Y Y N Y N Y Y N N Y (1) N Y (1) Y (1)

8 9 10

Seizure types

FSsG, hypomotor, eye and head deviation FSsG, hypotonia, eye deviation, tachycardia, cyanosis, automatisms FSsG, TCS, right head deviation, cyanosis FSsG, staring, psychomotor arrest, clonic seizures, apnea FSsG, hypomotor, head deviation, stare, cyanosis, apnea, tonic seizures FSsG, hypomotor or tonic, head deviation, stare, cyanosis, apnea, tonic seizures FSsG, TCS, staring, hypomotor, cyanosis, apnea 7

Clinical and neurophysiologic data are summarized in Table 1. During the disease course, clusters of seizures persisted together with

7

3.2. Follow-up

No.

Clinical characteristics of the eleven female patients are summarized in Table 1. Genetic analysis revealed nine new heterozygous PCDH19 mutations (Table 1). All but two variants are localized in exon 1; the mutations p.Ile781Asnfs*3 and c.2675-6A NG segregate in the exons 2 and 5, respectively. Based on family members study, all mutations resulted de novo. Seizure onset ranged from 3 to 38 months (mean: 11 months), and it was usually characterized by seizures in clusters, mostly associated with fever; in four cases, diagnosis was made after the first cluster of seizures, while in the other seven cases, it was made up to 34 years after seizure onset (mean: 4.6 years). Brain magnetic resonance was available for all patients, and it was normal in all of them.

Table 1 Summary of clinical and genetic characteristics of patients.

3.1. Diagnosis

11 13 14 6 11 38

SE (no.) Age (m)

3. Results

1 2 3 4 5 6

Afebrile

Follow-up Onset

Clusters of seizures

Genomic DNA was extracted from peripheral blood leukocytes of patients and their parents by using the QIAmp DNA Blood Mini Kit according to the manufacturer's protocol (Qiagen, Hilden, Germany). The six exons covering the coding regions of PCDH19 (Entrez Gene, Gene ID: 57526, accession number: EF676096.1) and their respective intron– exon boundaries were amplified by polymerase chain reaction (PCR) and cycle sequenced using BigDye 3.1 chemistry on an ABI 3130xl (Applied Biosystems, Foster City, CA, U.S.A.). The new identified PCDH19 mutations were checked in a control population of 150 ethnically matched controls, and segregation analysis was performed on all available members of a pedigree.

Febrile

2.1. Mutation analysis

FSsG FSsG FSsG FSsG FSsG FSsG

Seizure types

Ictal EEG

Left/T Right CP Right FC Bilateral FC Right/left T Bilateral F

Seizure freedom

Interictal EEG

We reviewed all patients with PCDH19 gene-related epilepsy referred to the Neurology Division of Bambino Gesù Children's Hospital in Rome. This is a private nonprofit research organization, providing health care and research on behalf of the Italian National Health System. It receives directly first-care patients, secondary patients regarding general pediatrics, and tertiary patients for specialist consultations. All medical records were carefully examined in order to review age and seizures at onset and during follow-up, number and frequency of clusters, status epilepticus (SE), and interictal and ictal EEGs. At this time, all patients have been evaluated with neurocognitive assessment or, when not possible, with parent report adaptive functioning three times during the disease. Cognitive assessment was performed by means of Griffiths Mental Developmental Scales (GMDS) or Wechsler Scales (WPPSI III or WISC III) according to the age and degree of cooperation of every single child; when a formal evaluation was not possible, interview with the parents was performed by means of Vineland Adaptive Behavior Scales (VABS) to obtain an adaptive profile [5–9]. Autism spectrum disorder symptoms were investigated clinically, and diagnosis was made according to DSM IV criteria [10]. A trained neuropsychologist performed clinical interviews, and all psychiatric diagnoses were formulated by the medical staff (including child neurologists and child neuropsychiatrists).

N N — 2 clusters/y N — 2 clusters/y N — monthly clusters N — 3 clusters/y Y — since 7 y

PCDH19 mutations

2. Material and methods

p.Tyr366X p.Pro393Leu p.Ile781Asnfs*3 p.Tyr366Leufs*10 c.2617-1GNA c.958dupG (p.Asp320Glyfs*22) de novo c.2675-6ANG

evaluation was performed since epilepsy onset and during the course of the disease.

c.1129GNC p.Pro567Leu c.1298TNC (p.Leu433Pro) de novo p.Pro236Ser

S. Cappelletti et al. / Epilepsy & Behavior 42 (2015) 36–40

Autistic

Attention deficit

Autistic

Autistic

Autistic and aggressive behavior

Mild attention deficit

Autistic

Attention deficit

Autistic

Autistic

Autistic

Normal

Hyperactivity Mild attention deficit Autistic

3y

3y

3y

5 y, 4 m

9 y, 11 m

10 y, 10 m

11 y, 10 m

17 y, 8 m

20 y

37 y

2

3

4

5

6

7

8

9

10

11

m: months; y: years; GQ = Global Quotient; IQ = Intelligence Quotient; VIQ = Verbal Intelligence Quotient; PIQ = Performance Intelligence Quotient; AQ = Adaptive Quotient.

Autistic

Anxiety/depressive

Autistic

Autistic

Mild attention deficit Learning disorder Autistic and aggressive behavior

Hyperactivity Attention deficit Autistic Hyperactivity Attention deficit Autistic

Mild disability GQ = 70 (3 y) Normal GQ = 89 (3 y) Normal GQ = 99 (3 y) Normal GQ = 95 (3 y) Moderate disability GQ = 40 (5 y) Normal IQ = 91 VIQ = 90 PIQ = 93 (9 y) Severe disability AQ = 36 (10 y) Severe disability AQ = 32 (11 y) Moderate disability IQ = 46 (16 y) Mild disability IQ = 62 VIQ = 75 PIQ = 57 (20 y) Moderate disability AQ = 28 (37 y) Attention deficit Hyperactivity Attention deficit Hyperactivity Mild attention deficit 3y 1

Behavior

Hyperactivity Mild attention deficit Mild attention deficit

Cognitive development Psychomotor development

Age No.

Table 2 summarizes the cognitive profile of all patients. Cognitive/developmental profile at this time appeared to be in the average range in four patients (nos. 2, 3, 4, and 6), without any sign of autism spectrum disorder or psychiatric disorders over time despite the recurrence of seizure clusters. However, in all of them, a delay in the acquisition of language that required an early referral to logotherapy was found; in all cases, an improvement was documented. In the four youngest patients (nos. 1, 2, 3, and 4), we were able to perform the same kind of test (GMDS) over time, and a detailed mental developmental profile is provided in Fig. 1. Different degrees of intellectual disability were detected in seven patients. Mild intellectual disability was evident in two patients (nos. 1 and 10), without symptoms suggestive of autism spectrum disorders. One of them presented anxiety and depression during adolescence. In the other five patients with moderate and severe intellectual disability, cognitive assessment was not performed because of poor cooperation, but different behavioral problems were detected, such as attention deficit and hyperactivity disorder, challenging and disruptive behavior, obsessive traits, and emotional disorders. All of them presented autistic features such as social withdrawal and isolation, hypomimia, stereotyped movements, high resistance to pain, and echolalic language. In all of them, the first psychiatric, autistic, and intellectual disability symptoms were more evident after the age of two years. Motor and gestural stereotyped movements decreased over time, with an improvement of eye contact and affective relationships for parents and

Table 2 Cognitive and behavior outcomes in patients with PCDH19-related epilepsy.

3.4. Cognitive profile

Mild disability GQ = 71 (2 y) Normal GQ = 95 (2 y) Normal GQ = 99 (2 y) Normal GQ = 98 (2 y) Moderate disability GQ = 43 (2 y) Borderline IQ = 80 VIQ = 89 PIQ = 76 (8 y) Severe disability AQ = 53 (9 y) Severe disability AQ = 30 (8 y) Moderate disability IQ = 46 (14 y) Mild disability IQ = 64 VIQ = 61 PIQ = 61 (8 y) Moderate disability AQ = 36 (11 y)

Follow-up Baseline

The neurologic examination at seizure onset appeared to be normal in all patients but one (no. 4) who presented a mild axial hypotonia, failing to achieve the autonomous sitting position at the age-appropriate time. Four girls currently present dyspraxia with some difficulties in fine motor skills (nos. 5, 9, 10, and 11); none of them show ataxia or neurological deficit or other movement disorders.

Mild attention deficit

3.3. Neurological examination

Mild disability GQ = 71 (1 y) Normal GQ = 91 (1 y) Normal GQ = 99 (1 y) Normal GQ = 98 (1 y) Moderate disability GQ = 47 (1 y) Normal GQ = 98 (3 y, 6 m) Moderate disability GQ = 40 (4 y) Moderate disability GQ = 51 (9 m) Moderate disability GQ = 50 (5 y) Normal GQ = 98 (4 y) Moderate disability GQ = 50 (5 y)

Behavior

Follow-up 2

Behavior

SE. In our series, 2 out of 11 patients presented several SE episodes during the follow-up. In all patients, seizure frequency was high at the onset of epilepsy; clusters recurred every 1–3 months, with a reduction in frequency during the follow-up. At last follow-up visit, five patients continued to present two or three clusters of seizures per year; 1 patient monthly. Fever susceptibility was usually more pronounced in the first years of disease, while, over time, afebrile clusters became prevalent; four patients presented both febrile and afebrile clusters, and four patients presented only afebrile seizures. Fever triggering clusters was usually mild, up to 38 °C. Four out of 11 patients on antiepileptic drugs are currently seizurefree (follow-up: 18–24 months). Ictal video-EEG revealed focal seizures in seven patients and a bilateral onset in the remaining four. In five patients (before the age of 10 years), affective symptoms were present. Although seizures and ictal EEG appeared to be stereotyped during a cluster, three patients presented both focal and generalized seizures during the same cluster. None of our patients experienced atonic or myoclonic seizures. Patient no. 10 experienced a cluster of hemiclonic seizures when she was seven years old. Two patients (patient nos. 8 and 10) presented brief absence seizures (10 to 15 s). Finally, five patients also presented isolated motor seizures between clusters. Interictal EEG showed normal background activity in four patients (nos. 2, 3, 6, and 10), while in five, EEG was characterized by focal or bilateral spikes and slow waves (nos. 5, 7, 8, 9, and 11). In two patients, we observed theta monomorphic activity in centroparietal regions, both during wakefulness and sleep (nos. 1 and 4).

Attention deficit Hyperactivity Attention deficit Hyperactivity Mild attention deficit

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Cognitive development

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Fig. 1. Developmental profile of patient nos. 1, 2, 3, and 4.

caregivers. During adolescence, they usually expressed restricted and repetitive interests, impulsivity, and uninhibited behavior. 4. Discussion In this study, we performed different neurocognitive evaluations and measured adaptive functions in patients with PCDH19. Overall, the results of our study revealed that certain variability has been documented regarding cognitive profile. We did not find a specific developmental profile for some reasons: spectrum of age is wide since we have patients with an age range between 2 and 38 years and electroclinical characteristics of patients are also heterogeneous and changing over time. Considering the data coming from this study, in six patients, despite the persistence of seizures in clusters, we found that neurocognitive evaluation revealed average mental development or mild intellectual disability. Mild intellectual disability was associated with mild anxious and depressive mood, although they had presented a sufficient adaptive behavior. In younger patients, we found that despite an average developmental quotient, they all presented a delay of expressive language acquisition, which required a referral to a speech therapy, resulting in improvement of verbal expression. This finding underlines that even in younger children who might appear as “normal” at first evaluation, subtle dysfunctions might be present and should be taken into account, since they can represent the first expression of a deviation from a normal developmental trajectory. Therefore, besides a cognitive evaluation, we consider necessary a language evaluation in these children, since this can allow an early referral to a rehabilitation therapy and a close neurocognitive monitoring to identify early any delay in the acquisition of new neurodevelopmental milestones. Five patients presented moderate or severe intellectual disability and autistic features. Neurologic disability (including cognitive and motor functions) in these patients appears to be stable over time, without signs of further deterioration as it might happen in other conditions such as Dravet syndrome [11]. Similar to PCDH19-related epilepsy, the other genetically determined epileptic syndromes are also associated with a high risk of intellectual disability and autism spectrum disorder. For example, patients with tuberous sclerosis or Dravet syndrome tend to have a higher occurrence of autistic-like features, if not autism proper, than that in other structural epilepsies [11]. As Brooks-Kayal pointed out, genetic factors

are implicated in specific early-onset epileptic encephalopathy, and the mechanisms responsible for epilepsy might also play a role in producing autistic features and intellectual disability [12]. About monogenic syndromes, some important differences should be acknowledged between Dravet syndrome and PCDH19-related epilepsy: in the first one, intellectual disability is more frequently observed during the first year, and then motor and cognitive deterioration became evident; in the second one, a significant risk of autistic disorder and intellectual disability might be present by the second year, without risks of motor deficit [1,13]. Mutations in the PCDH19 gene result in different neurological, cognitive, and behavioral disturbances. Such disturbances might be related to the deficit of cadherin expression in different cerebral areas that are involved in different functions. Protocadherin 19 is involved in several developmental processes such as axon outgrowth and synaptogenesis, which are known to play a key role in neurodevelopment. Therefore, a disturbance in this process might result in cognitive and behavioral disorders [14]. One point of interest in our study is that, through serial evaluations during the follow-up, there are more chances to better predict the cognitive and behavioral outcomes; moreover, the absence of language during the first year after the onset of epilepsy might have a negative prognostic significance. In the same period, hyperactivity, tendency to isolation, irritability, poor eye contact, and alteration of sleep/wake rhythm were mainly symptoms evolving in a short period of time to pervasive developmental disorder. Some limitation in this study should be acknowledged. Despite the fact that the findings are novel and interesting, due to the limited number of cases, a statistical analysis could not be performed, and results are descriptive. Neuropsychological evaluations were limited to cognitive functions for most patients or parent-reported adaptive findings; therefore, we could not exclude subtle abnormalities in other neuropsychological abilities. Furthermore, the young age of some patients at the last reported follow-up does not allow us to delineate a developmental trajectory for these girls, since an average IQ in the preschool age does not guarantee a normal cognitive outcome or the absence of neuropsychiatric comorbidities. Therefore, a larger cohort and long-term followup might be useful to define the cognitive and behavioral profiles in PCDH19-related epilepsy. A longitudinal cognitive evaluation from the onset of the epilepsy and during the follow-up associated with a strict rehabilitation therapy is strongly suggested in patients with PCDH19-related epilepsy.

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Conflict of interest We confirm that we have no conflict of interest. Acknowledgments We thank the patients and the families for their cooperation. References [1] Dibbens LM, Tarpey PS, Hynes K, Bayly MA, Scheffer IE, Smith R, et al. X-linked protocadherin 19 mutations cause female limited epilepsy and cognitive impairment. Nat Genet 2008;40:776–81. [2] Marini C, Darra F, Specchio N, Mei D, Terracciano, Parmeggiani L, et al. Focal seizures with affective symptoms are a major feature of PCDH19 gene-related epilepsy. Epilepsia 2012;53:2111–9. [3] Specchio N, Marini C, Terracciano A, Mei D, Trivisano M, Sicca F, et al. Spectrum of phenotypes in female patients with epilepsy due to protocadherin 19 mutations. Epilepsia 2011;52:1251–7. [4] Camacho A, Simon R, Sanz R, Viñuela A, Martínez-Salio A, Mateos F. Cognitive and behavioral profile in females with epilepsy with PCDH19 mutation: two novel mutations and review of the literature. Epilepsy Behav 2012;24:134–7.

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