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Charcot–Marie–Tooth 2-like presentation of an Algerian family with giant axonal neuropathy
Neuromuscular Disorders 10 (2000) 592±598
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Charcot±Marie±Tooth 2-like presentation of an Algerian family with giant axonal neuropathy R. Zemmouri a, H. Azzedine b, c, S. Assami a, N. Kitouni d, J.M. Vallat e, T. Maisonobe f, T. Hamadouche b, M. Kessaci g, B. Mansouri g, E. Le Guern c, D. Grid h, M. Tazir a,* b
a Service de Neurologie, CHU Mustapha, Alger Centre, Alger 16000, Algeria Laboratoire de Biologie MoleÂculaire, Institut Pasteur d'Algerie, Alger, Algeria c INSERM U.289, Paris, France d Service de Neurologie, CHU A.Ait Idir, Alger, Algeria e Service de Neuropathologie, CHR, Limoges, France f Laboratoire de Neuropathologie R. Escourolle, Paris, France g Service d'Imagerie MeÂdicale, CHU Bab El Oued, Alger, Algeria h Genethon III, Evry, France
Received 15 December 1999; received in revised form 10 March 2000; accepted 29 March 2000
Abstract Giant axonal neuropathy is a rare autosomal recessive childhood disorder characterized by a peripheral neuropathy and features of central nervous system involvement. We describe four patients belonging to a consanguineous Algerian family with late onset (6±10 years) slowly progressive autosomal recessive giant axonal neuropathy. The propositus presented with a Charcot±Marie±Tooth 2-like phenotype with foot deformity, distal amyotrophy of lower limbs, are¯exia and distal lower limb hypoesthesia. Central nervous system involvement occurred 10 years later with mild cerebellar dysarthria and nystagmus in the propositus and 16 years after onset, a spastic paraplegia in the oldest patient. The two youngest patients (13 and 8 years old) do not present any signs of central nervous involvement. Magnetic resonance imaging showed cerebellar atrophy in the two older. Nerve biopsy showed moderate axonal loss with several giant axons ®lled with neuro®laments. Genetic study established a linkage to chromosome 16q locus. This clinical presentation differs from the classical form of giant axonal neuropathy. q 2000 Elsevier Science B.V. All rights reserved. Keywords: Giant axonal neuropathy; Locus 16q
1. Introduction Giant axonal neuropathy (GAN), ®rst described in 1972 [1,2] is a rare hereditary disorder characterized by a progressive motor and sensory neuropathy, signs of central nervous system (CNS) involvement including cerebellar and pyramidal signs, mental retardation and electroencephalographic (EEG) abnormalities [3]. Most reported cases presented kinky hair. Peripheral nerve biopsies characteristically show giant axonal swellings ®lled with neuro®laments. This striking feature is usually associated with moderate axonal loss. The GAN gene was localized by homozygosity mapping to chromosome 16q24 between D16S3098 and D16S505 markers [4,5]. Genetic heterogeneity was not described for the autosomal recessive form of GAN. * Corresponding author. E-mail address: [email protected] (M. Tazir).
We report a clinical, electrophysiological, pathological and genetic study of an Algerian family with four siblings affected with a peculiar clinical form of GAN.
2. Patients and methods The family originates from a village near MeÂdeÂa, 120 km southwest of Algiers. 2.1. Clinical evaluation All the members (parents and sibs) were examined by two of the authors (R.Z, M.T). The four patients underwent ophthalmological, cardiological, neuropsychological and imaging investigations, and CSF study.
0960-8966/00/$ - see front matter q 2000 Elsevier Science B.V. All rights reserved. PII: S09 60-8966(00)0014 1-3
R. Zemmouri et al. / Neuromuscular Disorders 10 (2000) 592±598
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Table 1 Clinical data a Patients
Sex
Age at onset (years)
Age at last exam (years)
Are¯exia
Muscular atrophy
Distal sensory impairment
Foot deformities
CNS involvement signs
13 (MH)
M
6
22
Ankle jerk
Distal UL and LL
1
PP
15 (SH)
M
5
16
Ankle jerk
Distal UL and LL
±
PC/EV
16 (AH) 18 (HH)
F M
6 7
14 9
Ankle jerk Ankle jerk
Distal LL ±
± ±
PC/EV PC
Nystagmus spastic paraplegia onset at 21 years Nystagmus dysarthria onset at 16 years No No
a
Abbreviations: UL, upper limbs; LL, lower limbs; PP, pes planus; PC. pes cavus; EV, equinovarus; CNS, central nervous system.
2.2. Electrophysiological studies The electrophysiological recordings of parents and siblings included EEG, EMG, nerve conduction velocities (NCV) and evoked potentials. Median (elbow±wrist), peroneal (head of ®bula±ankle) MNCV, distal latencies and muscle action potential amplitude were registered with surface electrodes. Sensory action potentials were recorded antidromically from the median nerve and the sural nerve. Needle EMG examination was performed on distal and proximal muscles. Examination of evoked potentials exploration included visual (VEP) brainstem auditory evoked response (BAER) and somatosensory evoked potentials (SEP). 2.3. Pathology The oldest (MH) and the third (AH) patients underwent biopsy on peroneal super®cial nerve examined by JMV and TM. For analysis of nerve biopsy, fascicles of the nerve were ®xed in formaldehyde (10%) and embedded in paraf®n. Routine sections were stained used conventional method. Others fascicles were ®xed in buffered in glutaraldehyde, processed and embedded in epon. Semi-thin sections were stained with phenyldiamine and viewed through a Phillips CM10 electron microscope. Sample of the nerves were also teased. 2.4. Linkage analysis Blood samples from the eight family members were
obtained after informed consent, and genomic DNA was extracted in the molecular biology laboratory of the Institut Pasteur, Algiers, using standard procedures. Microsatellite markers localized in 16q24 were selected from the Genethon human linkage map [6]. The markers were ampli®ed by the polymerase chain reaction (PCR) under the previously described conditions [7]. Pairwise lod scores were calculated using the MLINK program of the FASTLINK package [8], assuming a fully penetrant autosomal recessive trait with a disease allele frequency of 0.0001 and equal recombination fraction in males and females. We assigned equal frequencies to the alleles observed in the studied family. At risk members no. 14 and 17 who were clinically and electrophysiologically normal at age 18 and 9, respectively, were considered as non affected. Haplotypes were constructed according to the principles of Thomson [9]. The order of markers was that of the consensus CEPH/ Genethon chromosome 16 linkage map of GDB.
3. Results 3.1. Clinical and electrophysiological ®ndings The propositus (SH) was ®rst seen at 13 years of age. He had dif®culty climbing stairs and running. It was thought that his equinovarus feet were the cause of these dif®culties. This deformation appeared at the age of 6 years and worsened progressively. At 13 years of age, neurological
Table 2 Electrophysiological data a Patient
Motor nerves
Sensory nerves
Median
13 (MH) 15 (SH) 16 (AH) 18 (HH) a
Peroneal
Median
Sural
A (mV)
DL (ms)
CV (m/s)
A (mV)
DL (ms)
CV (m/s)
A (mV)
DL (ms)
CV (m/s)
A (mV)
DL (ms)
CV (m/s)
2 1.9 5 2.7
5 4.7 4 2
52 58 56 66
NR NR 0.4 0.8
NR NR 5 4.5
NR NR 51 42
15 7 16 40
2.5 2.7 1.9 2
51.6 48.7 55 46
NR NR NR 8
NR NR NR 3
NR NR NR 34
Abbreviations: A, amplitude; DL, distal latency; CV, conduction velocity; NR, not recorded.
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Fig. 1. Semi-thin sections. Presence of numerous giant axons in this fascicle (original magni®cation (£100).
Fig. 2. EM migrograph: giant axon: no myelin sheath is visible (Bar 5 mm).
R. Zemmouri et al. / Neuromuscular Disorders 10 (2000) 592±598
595
Fig. 3. EM migrograph: at high magni®cation of this giant axon an intense proliferation of neuro®laments is clearly seen. Around it there is a sheath (Bar 0.2 mm).
examination showed moderate steppage gait, distal lower limbs weakness and muscle atrophy and bilateral pes cavus with severe equinovarus. Tactile, vibration and pinprick sensations were normal. Deep tendon re¯exes were all present except for ankle jerks (Table 1). At 14 years he underwent surgery to the feet after which he could not walk without crutches. Electrophysiological studies showed normal motor nerve conduction velocities, absent sural potential (Table 2) and electromyogram suggesting a neurogenic pattern. These data were compatible with sensory motor axonal neuropathy. At this stage, after the disclosure of two similar cases in this family, the evoked diagnosis was familial Charcot± Marie±Tooth 2 (CMT2). When seen at 16 years of age, he had moderate distal upper limbs weakness and muscle atrophy plus mild dysarthria and nystagmus. The oldest patient (MH) was seen ®rst at 19 years of age. The clinical picture was similar to the propositus except for foot deformities. He had pes planus with distorted toes and could not walk on heels or toes. Electrophysiological results were consistent with sensory motor axonal neuropathy (Table 2). When examined at 22 years of age, central nervous signs were present with spastic gait, brisk patellar re¯exes, silent plantar re¯ex, mild dysarthria and nystagmus. The third patient's (AH) main complaint was dif®culty in running since she was
Fig. 4. Han family pedigree.
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R. Zemmouri et al. / Neuromuscular Disorders 10 (2000) 592±598
Table 3 Two point lod scores for linkage between the GAN locus and the informative 16q24 markers in Han family Markers
Recombination rates (u) 0.0
0.01
0.05
0.1
0.2
0.3
0.4
Zmax
2 in®ni 2.57 2.57 1.55 2.43
2 0.96 2.51 2.51 1.52 2.38
0.25 2.30 2.30 1.37 2.19
0.61 2.03 2.03 1.19 1.94
0.69 1.47 1.47 0.82 1.42
0.48 0.89 0.89 0.46 0.87
0.17 0.32 0.32 0.14 0.32
0.96 2.57 2.57 1.55 2.43
1 D16S518 1 D16S516 1 D16S507 1 D16S3098 1 D16S3091
7 years old; when seen at 14 years, she had distal lower limb weakness. She could not walk on her heels and had pes cavus with mild equinovarus. No central nervous system involvement was apparent. The fourth patient (HH) did not have any symptoms, but had dif®culty walking on his heels and had no ankle re¯exes on examination at 7 years of age. EMG results for these two youngest patients were consistent with sensory motor axonal neuropathy (Table 2). All patients had normal mental status and ophthalmological and cardiological examinations were normal and none of them has kinky hair. CSF studies and evoked potentials exploration were normal. 3.2. Histopathologic study There was only a slight reduction in the number of myelinated ®bers. On semi-thin sections numerous giant axons were seen in all fascicles examined (Fig. 1); the myelin sheaths around them were either absent or unusually thin (Fig. 2). In teased preparations, these axonal dilatations were segmental. Ultrastructural examination revealed intense proliferation of neuro®laments which push the endoplasmic reticulum and mitochondria out toward the periphery near the axolemma (Fig. 3). There were also a number of lesions of demyelination
inheritance in GAN, which is the mode of inheritance which has been reported exclusively to date [5] although a family with dominant hereditary motor and sensory neuropathy type II whose sural nerves showed axonal swellings with neuro®lament accumulations but with a late onset and without central nervous involvement has already been reported [10]. In our family, the condition was revealed by a slowly progressive distal motor and sensory neuropathy diagnosed as autosomal recessive CMT2. In the majority of reported GAN cases, CNS involvement is described early in the course of the disease [11±16] whereas in this family it occurred at 10 and 16 years after the onset in the propositus and his oldest brother respectively. The two youngest patients (13 and 9 years old) did not present any sign of CNS involvement . In this respect, our cases are similar to
3.3. Linkage analysis As peripheral nerve biopsy showed typical features of GAN in patients MH and AH, the locus for GAN in 16q24 was tested in the family [4,5]. Homozygosity in all patients was observed for markers D16S516, D16S507, D16S 3098 and D16S3091 (Fig. 4). For all these microsatellites, bipoint analyses generated positive lod scores which reached a value of 2.57 at (0.00 for D16S507 and D16S516 (Table 1), con®rming linkage between the disease and the GAN locus. As the homozygosity region was larger than those de®ned by both Ben Hamida et al. [4] and Flanigan et al. [5], we were unable to reduce the genetic interval (Table 3). 4. Discussion This consanguineous family with four affected siblings and healthy parents complies with autosomal recessive (AR)
Fig. 5. Axial section of brain MR (SH) show moderate cerebral atrophy.
R. Zemmouri et al. / Neuromuscular Disorders 10 (2000) 592±598
the case reported by Malandrini et al. [17], a 17-year-old girl with giant axonal neuropathy and subclinical involvement of the CNS. Neither mental retardation nor EEG abnormalities were found in our family. We noted also the absence of hair abnormality which has been reported in some cases [5,11,14,15]. Moreover we can notice a heterogeneity of clinical signs in the two brothers: cerebellar signs and prominent pes cavus and varus in the propositus and pyramidal signs and pes planus in the eldest patient. The evolution of the disease in this family is slowly progressive. At 22 years of age, the oldest patient is still ambulant and independent. Many reported cases are wheel chair bound or have died by the second decade [11,15,18,19]. However some reports noted a protracted course [14±16,20] and in the family reported by Ben Hamida et al. [21], two patients had a slowly progressive course and became bedridden after more than 20 years of disease evolution. In our patients magnetic resonance imaging (MRI) examination revealed mild cerebral and cerebellar atrophy in the propositus (Fig. 5) and the oldest patient (Fig. 6) but there were no signs of demyelination or white matter disease as shown in previous reports [4,15,18,22]. The MRI examination was normal in the third and fourth patients. Ben Hamida et al. [4] localized GAN to 16q24 by homozygosity mapping
Fig. 6. Axial section of brain MR (MH) show moderate cerebral atrophy.
597
in three unrelated Tunisian families who shared a slow course of the disease. Flanigan et al. [5] con®rmed the linkage in ®ve consanguineous families but the affected cases had a progressive severe peripheral neuropathy with early onset and remarkable kinky hair. Ben Hamida et al. [4] suggested possible genetic heterogeneity and referred to the locus as GAN1. Our family share the same gene localization Fig. 4 although their clinical picture is somewhat different with protracted course, late involvement of central nervous system and absence of kinky hair. This variability of phenotype may correlate with an allelic heterogeneity. Acknowledgements The authors would like to thank the Association Francaise contre les Myopathies (AFM) Genethon III and the Department of Medecine, University of Algiers for their support. References [1] Asbury AK, Gale MK, Cox SC, et al. Giant axonal neuropathy: a unique case with segmental neuro®lamentous masses. Acta Neuropathol 1972;20:237±247. [2] Berg BO, Rosenberg SH, Asbury AK. Giant axonal neuropathy. Pediatrics 1972;49:849±899. [3] Igisu H, Ohta M, Tabira T, Hosowaka S, Goto I. Giant axonal neuropathy: a clinical entity affecting the central nervous system as the peripheral nervous system. Neurology 1975;25:717±721. [4] Ben Hamida C, Cavalier C, Belal L, et al. Homozygosity mapping of giant axonal neuropathy gene to chromosome 16q24.1. Neurogenetics 1997;1:129±133. [5] Flanigan KM, Crawford TO, Grif®n JW, et al. Localisation of the giant axonal neuropathy gene to chromosome 16q24. Ann Neurol 1998;43:143±148. [6] Dib C, Faure S, Fizames C, et al. A comprehensive genetic map of the human genome based on 5264 microsatellites. Nature 1966;380:152± 154. [7] Bouhouche A, Benomar A, Birouk N, et al. A locus for an axonal form of autosomal recessive Charcot±Marie±Tooth disease maps to chromosome 1q21.2±q21.3. Am J Hum Genet 1999;65:722±727. [8] ShaÈffer AA, Gupta SK, Cottingham RW. Avoiding recomputation in genetic linkage analysis. Hum Hered 1994;44:225±237. [9] Thompson EA. Crossover counts and likehood linkage analysis. IMA J Math Appl Med Biol 1987;4:93±108. [10] Vogel P, Gabriel M, Goebel HH, Dyck PJ. Hereditary motor sensory neuropathy type II with neuro®lament accumulation: new ®nding or new disorder. Ann Neurol 1985;17:445±461. [11] Ouvrier RA. Giant axonal neuropathy. A review. Brain Dev 1989;11:207±214. [12] Gambarelli D, Hassoun J, Pellissier JF, Livet MO, Pinsard N, Toga M. Giant axonal neuropathy: involvement of peripheral nerve, mesenteric and extra neuronal area. Acta Neuropathol (Berl) 1977;39:226±261. [13] Ionasescu V, Searby CH, Rubenstein P, Sandra A, Cancilla P, Robillard J. Giant axonal neuropathy: normal protein composition of neuro®laments. J Neurol Neurosurg Psychiatry 1983;46:551±554. [14] Tandan R, Little BW, Emery ES, Good PS, Pendlebury W, Bradley WG. Childhood giant axonal neuropathy: case report and review of the literature. J Neurol Sci 1987;82:205±228. [15] Lampl Y, Eshel E, Ben-David II, Gilad R, Saravo-Pinhas I, Sandbank U. Giant axonal neuropathy: predominant central system manifestation. Dev Med Child Neurol 1992;34:164±169.
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[16] Richen P, Tandan R. Giant axonal neuropathy: progressive clinical and radiologic CNS involvement. Neurology 1992;42:2220±2222. [17] Malandrini A, Dotti MT, Basttisti C, Villanova M, Capocchi G, Federico A. Giant axonal neuropathy with subclinical involvement of the central nervous system: case report. J Neurol Sci 1998;158:232±235. [18] BuissonieÁre RF, Routon MC, Robain O, Ponsot G, Arthuis M. Neuropathie aÁ axones geÂants: maladie des ®laments intermediaires avec atteinte du systeÁme nerveux peÂripheÂrique and central. Rev Neurol (Paris) 1989;145:355±361. [19] Thomas C, Love S, Powell HC, et al. Giant axonal neuropathy: corre-
lation of clinical ®ndings with post mortem neuropathology. Ann Neurol 1987;22:79±84. [20] Dooley JM, Oshima V, Becker LE, Murphy EG. Clinical progressive of giant axonal neuropathy of 12 year period. Can J Neurol Sci 1981;8:321±323. [21] Ben Hamida M, Hentati F, Ben Hamida C. Giant axonal neuropathy with inherited multisystem degeneration in a Tunisian kindred. Neurology 1990;40:245±259. [22] Guazzi GC, Malandrini A, Gerli R, Federico A. Giant axonal neuropathy in 2 siblings a generalized disorder of intermediate ®laments. Eur Neurol 1991;31:50±56.
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Charcot±Marie±Tooth 2-like presentation of an Algerian family with giant axonal neuropathy R. Zemmouri a, H. Azzedine b, c, S. Assami a, N. Kitouni d, J.M. Vallat e, T. Maisonobe f, T. Hamadouche b, M. Kessaci g, B. Mansouri g, E. Le Guern c, D. Grid h, M. Tazir a,* b
a Service de Neurologie, CHU Mustapha, Alger Centre, Alger 16000, Algeria Laboratoire de Biologie MoleÂculaire, Institut Pasteur d'Algerie, Alger, Algeria c INSERM U.289, Paris, France d Service de Neurologie, CHU A.Ait Idir, Alger, Algeria e Service de Neuropathologie, CHR, Limoges, France f Laboratoire de Neuropathologie R. Escourolle, Paris, France g Service d'Imagerie MeÂdicale, CHU Bab El Oued, Alger, Algeria h Genethon III, Evry, France
Received 15 December 1999; received in revised form 10 March 2000; accepted 29 March 2000
Abstract Giant axonal neuropathy is a rare autosomal recessive childhood disorder characterized by a peripheral neuropathy and features of central nervous system involvement. We describe four patients belonging to a consanguineous Algerian family with late onset (6±10 years) slowly progressive autosomal recessive giant axonal neuropathy. The propositus presented with a Charcot±Marie±Tooth 2-like phenotype with foot deformity, distal amyotrophy of lower limbs, are¯exia and distal lower limb hypoesthesia. Central nervous system involvement occurred 10 years later with mild cerebellar dysarthria and nystagmus in the propositus and 16 years after onset, a spastic paraplegia in the oldest patient. The two youngest patients (13 and 8 years old) do not present any signs of central nervous involvement. Magnetic resonance imaging showed cerebellar atrophy in the two older. Nerve biopsy showed moderate axonal loss with several giant axons ®lled with neuro®laments. Genetic study established a linkage to chromosome 16q locus. This clinical presentation differs from the classical form of giant axonal neuropathy. q 2000 Elsevier Science B.V. All rights reserved. Keywords: Giant axonal neuropathy; Locus 16q
1. Introduction Giant axonal neuropathy (GAN), ®rst described in 1972 [1,2] is a rare hereditary disorder characterized by a progressive motor and sensory neuropathy, signs of central nervous system (CNS) involvement including cerebellar and pyramidal signs, mental retardation and electroencephalographic (EEG) abnormalities [3]. Most reported cases presented kinky hair. Peripheral nerve biopsies characteristically show giant axonal swellings ®lled with neuro®laments. This striking feature is usually associated with moderate axonal loss. The GAN gene was localized by homozygosity mapping to chromosome 16q24 between D16S3098 and D16S505 markers [4,5]. Genetic heterogeneity was not described for the autosomal recessive form of GAN. * Corresponding author. E-mail address: [email protected] (M. Tazir).
We report a clinical, electrophysiological, pathological and genetic study of an Algerian family with four siblings affected with a peculiar clinical form of GAN.
2. Patients and methods The family originates from a village near MeÂdeÂa, 120 km southwest of Algiers. 2.1. Clinical evaluation All the members (parents and sibs) were examined by two of the authors (R.Z, M.T). The four patients underwent ophthalmological, cardiological, neuropsychological and imaging investigations, and CSF study.
0960-8966/00/$ - see front matter q 2000 Elsevier Science B.V. All rights reserved. PII: S09 60-8966(00)0014 1-3
R. Zemmouri et al. / Neuromuscular Disorders 10 (2000) 592±598
593
Table 1 Clinical data a Patients
Sex
Age at onset (years)
Age at last exam (years)
Are¯exia
Muscular atrophy
Distal sensory impairment
Foot deformities
CNS involvement signs
13 (MH)
M
6
22
Ankle jerk
Distal UL and LL
1
PP
15 (SH)
M
5
16
Ankle jerk
Distal UL and LL
±
PC/EV
16 (AH) 18 (HH)
F M
6 7
14 9
Ankle jerk Ankle jerk
Distal LL ±
± ±
PC/EV PC
Nystagmus spastic paraplegia onset at 21 years Nystagmus dysarthria onset at 16 years No No
a
Abbreviations: UL, upper limbs; LL, lower limbs; PP, pes planus; PC. pes cavus; EV, equinovarus; CNS, central nervous system.
2.2. Electrophysiological studies The electrophysiological recordings of parents and siblings included EEG, EMG, nerve conduction velocities (NCV) and evoked potentials. Median (elbow±wrist), peroneal (head of ®bula±ankle) MNCV, distal latencies and muscle action potential amplitude were registered with surface electrodes. Sensory action potentials were recorded antidromically from the median nerve and the sural nerve. Needle EMG examination was performed on distal and proximal muscles. Examination of evoked potentials exploration included visual (VEP) brainstem auditory evoked response (BAER) and somatosensory evoked potentials (SEP). 2.3. Pathology The oldest (MH) and the third (AH) patients underwent biopsy on peroneal super®cial nerve examined by JMV and TM. For analysis of nerve biopsy, fascicles of the nerve were ®xed in formaldehyde (10%) and embedded in paraf®n. Routine sections were stained used conventional method. Others fascicles were ®xed in buffered in glutaraldehyde, processed and embedded in epon. Semi-thin sections were stained with phenyldiamine and viewed through a Phillips CM10 electron microscope. Sample of the nerves were also teased. 2.4. Linkage analysis Blood samples from the eight family members were
obtained after informed consent, and genomic DNA was extracted in the molecular biology laboratory of the Institut Pasteur, Algiers, using standard procedures. Microsatellite markers localized in 16q24 were selected from the Genethon human linkage map [6]. The markers were ampli®ed by the polymerase chain reaction (PCR) under the previously described conditions [7]. Pairwise lod scores were calculated using the MLINK program of the FASTLINK package [8], assuming a fully penetrant autosomal recessive trait with a disease allele frequency of 0.0001 and equal recombination fraction in males and females. We assigned equal frequencies to the alleles observed in the studied family. At risk members no. 14 and 17 who were clinically and electrophysiologically normal at age 18 and 9, respectively, were considered as non affected. Haplotypes were constructed according to the principles of Thomson [9]. The order of markers was that of the consensus CEPH/ Genethon chromosome 16 linkage map of GDB.
3. Results 3.1. Clinical and electrophysiological ®ndings The propositus (SH) was ®rst seen at 13 years of age. He had dif®culty climbing stairs and running. It was thought that his equinovarus feet were the cause of these dif®culties. This deformation appeared at the age of 6 years and worsened progressively. At 13 years of age, neurological
Table 2 Electrophysiological data a Patient
Motor nerves
Sensory nerves
Median
13 (MH) 15 (SH) 16 (AH) 18 (HH) a
Peroneal
Median
Sural
A (mV)
DL (ms)
CV (m/s)
A (mV)
DL (ms)
CV (m/s)
A (mV)
DL (ms)
CV (m/s)
A (mV)
DL (ms)
CV (m/s)
2 1.9 5 2.7
5 4.7 4 2
52 58 56 66
NR NR 0.4 0.8
NR NR 5 4.5
NR NR 51 42
15 7 16 40
2.5 2.7 1.9 2
51.6 48.7 55 46
NR NR NR 8
NR NR NR 3
NR NR NR 34
Abbreviations: A, amplitude; DL, distal latency; CV, conduction velocity; NR, not recorded.
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R. Zemmouri et al. / Neuromuscular Disorders 10 (2000) 592±598
Fig. 1. Semi-thin sections. Presence of numerous giant axons in this fascicle (original magni®cation (£100).
Fig. 2. EM migrograph: giant axon: no myelin sheath is visible (Bar 5 mm).
R. Zemmouri et al. / Neuromuscular Disorders 10 (2000) 592±598
595
Fig. 3. EM migrograph: at high magni®cation of this giant axon an intense proliferation of neuro®laments is clearly seen. Around it there is a sheath (Bar 0.2 mm).
examination showed moderate steppage gait, distal lower limbs weakness and muscle atrophy and bilateral pes cavus with severe equinovarus. Tactile, vibration and pinprick sensations were normal. Deep tendon re¯exes were all present except for ankle jerks (Table 1). At 14 years he underwent surgery to the feet after which he could not walk without crutches. Electrophysiological studies showed normal motor nerve conduction velocities, absent sural potential (Table 2) and electromyogram suggesting a neurogenic pattern. These data were compatible with sensory motor axonal neuropathy. At this stage, after the disclosure of two similar cases in this family, the evoked diagnosis was familial Charcot± Marie±Tooth 2 (CMT2). When seen at 16 years of age, he had moderate distal upper limbs weakness and muscle atrophy plus mild dysarthria and nystagmus. The oldest patient (MH) was seen ®rst at 19 years of age. The clinical picture was similar to the propositus except for foot deformities. He had pes planus with distorted toes and could not walk on heels or toes. Electrophysiological results were consistent with sensory motor axonal neuropathy (Table 2). When examined at 22 years of age, central nervous signs were present with spastic gait, brisk patellar re¯exes, silent plantar re¯ex, mild dysarthria and nystagmus. The third patient's (AH) main complaint was dif®culty in running since she was
Fig. 4. Han family pedigree.
596
R. Zemmouri et al. / Neuromuscular Disorders 10 (2000) 592±598
Table 3 Two point lod scores for linkage between the GAN locus and the informative 16q24 markers in Han family Markers
Recombination rates (u) 0.0
0.01
0.05
0.1
0.2
0.3
0.4
Zmax
2 in®ni 2.57 2.57 1.55 2.43
2 0.96 2.51 2.51 1.52 2.38
0.25 2.30 2.30 1.37 2.19
0.61 2.03 2.03 1.19 1.94
0.69 1.47 1.47 0.82 1.42
0.48 0.89 0.89 0.46 0.87
0.17 0.32 0.32 0.14 0.32
0.96 2.57 2.57 1.55 2.43
1 D16S518 1 D16S516 1 D16S507 1 D16S3098 1 D16S3091
7 years old; when seen at 14 years, she had distal lower limb weakness. She could not walk on her heels and had pes cavus with mild equinovarus. No central nervous system involvement was apparent. The fourth patient (HH) did not have any symptoms, but had dif®culty walking on his heels and had no ankle re¯exes on examination at 7 years of age. EMG results for these two youngest patients were consistent with sensory motor axonal neuropathy (Table 2). All patients had normal mental status and ophthalmological and cardiological examinations were normal and none of them has kinky hair. CSF studies and evoked potentials exploration were normal. 3.2. Histopathologic study There was only a slight reduction in the number of myelinated ®bers. On semi-thin sections numerous giant axons were seen in all fascicles examined (Fig. 1); the myelin sheaths around them were either absent or unusually thin (Fig. 2). In teased preparations, these axonal dilatations were segmental. Ultrastructural examination revealed intense proliferation of neuro®laments which push the endoplasmic reticulum and mitochondria out toward the periphery near the axolemma (Fig. 3). There were also a number of lesions of demyelination
inheritance in GAN, which is the mode of inheritance which has been reported exclusively to date [5] although a family with dominant hereditary motor and sensory neuropathy type II whose sural nerves showed axonal swellings with neuro®lament accumulations but with a late onset and without central nervous involvement has already been reported [10]. In our family, the condition was revealed by a slowly progressive distal motor and sensory neuropathy diagnosed as autosomal recessive CMT2. In the majority of reported GAN cases, CNS involvement is described early in the course of the disease [11±16] whereas in this family it occurred at 10 and 16 years after the onset in the propositus and his oldest brother respectively. The two youngest patients (13 and 9 years old) did not present any sign of CNS involvement . In this respect, our cases are similar to
3.3. Linkage analysis As peripheral nerve biopsy showed typical features of GAN in patients MH and AH, the locus for GAN in 16q24 was tested in the family [4,5]. Homozygosity in all patients was observed for markers D16S516, D16S507, D16S 3098 and D16S3091 (Fig. 4). For all these microsatellites, bipoint analyses generated positive lod scores which reached a value of 2.57 at (0.00 for D16S507 and D16S516 (Table 1), con®rming linkage between the disease and the GAN locus. As the homozygosity region was larger than those de®ned by both Ben Hamida et al. [4] and Flanigan et al. [5], we were unable to reduce the genetic interval (Table 3). 4. Discussion This consanguineous family with four affected siblings and healthy parents complies with autosomal recessive (AR)
Fig. 5. Axial section of brain MR (SH) show moderate cerebral atrophy.
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the case reported by Malandrini et al. [17], a 17-year-old girl with giant axonal neuropathy and subclinical involvement of the CNS. Neither mental retardation nor EEG abnormalities were found in our family. We noted also the absence of hair abnormality which has been reported in some cases [5,11,14,15]. Moreover we can notice a heterogeneity of clinical signs in the two brothers: cerebellar signs and prominent pes cavus and varus in the propositus and pyramidal signs and pes planus in the eldest patient. The evolution of the disease in this family is slowly progressive. At 22 years of age, the oldest patient is still ambulant and independent. Many reported cases are wheel chair bound or have died by the second decade [11,15,18,19]. However some reports noted a protracted course [14±16,20] and in the family reported by Ben Hamida et al. [21], two patients had a slowly progressive course and became bedridden after more than 20 years of disease evolution. In our patients magnetic resonance imaging (MRI) examination revealed mild cerebral and cerebellar atrophy in the propositus (Fig. 5) and the oldest patient (Fig. 6) but there were no signs of demyelination or white matter disease as shown in previous reports [4,15,18,22]. The MRI examination was normal in the third and fourth patients. Ben Hamida et al. [4] localized GAN to 16q24 by homozygosity mapping
Fig. 6. Axial section of brain MR (MH) show moderate cerebral atrophy.
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in three unrelated Tunisian families who shared a slow course of the disease. Flanigan et al. [5] con®rmed the linkage in ®ve consanguineous families but the affected cases had a progressive severe peripheral neuropathy with early onset and remarkable kinky hair. Ben Hamida et al. [4] suggested possible genetic heterogeneity and referred to the locus as GAN1. Our family share the same gene localization Fig. 4 although their clinical picture is somewhat different with protracted course, late involvement of central nervous system and absence of kinky hair. This variability of phenotype may correlate with an allelic heterogeneity. Acknowledgements The authors would like to thank the Association Francaise contre les Myopathies (AFM) Genethon III and the Department of Medecine, University of Algiers for their support. References [1] Asbury AK, Gale MK, Cox SC, et al. Giant axonal neuropathy: a unique case with segmental neuro®lamentous masses. Acta Neuropathol 1972;20:237±247. [2] Berg BO, Rosenberg SH, Asbury AK. Giant axonal neuropathy. Pediatrics 1972;49:849±899. [3] Igisu H, Ohta M, Tabira T, Hosowaka S, Goto I. Giant axonal neuropathy: a clinical entity affecting the central nervous system as the peripheral nervous system. Neurology 1975;25:717±721. [4] Ben Hamida C, Cavalier C, Belal L, et al. Homozygosity mapping of giant axonal neuropathy gene to chromosome 16q24.1. Neurogenetics 1997;1:129±133. [5] Flanigan KM, Crawford TO, Grif®n JW, et al. Localisation of the giant axonal neuropathy gene to chromosome 16q24. Ann Neurol 1998;43:143±148. [6] Dib C, Faure S, Fizames C, et al. A comprehensive genetic map of the human genome based on 5264 microsatellites. Nature 1966;380:152± 154. [7] Bouhouche A, Benomar A, Birouk N, et al. A locus for an axonal form of autosomal recessive Charcot±Marie±Tooth disease maps to chromosome 1q21.2±q21.3. Am J Hum Genet 1999;65:722±727. [8] ShaÈffer AA, Gupta SK, Cottingham RW. Avoiding recomputation in genetic linkage analysis. Hum Hered 1994;44:225±237. [9] Thompson EA. Crossover counts and likehood linkage analysis. IMA J Math Appl Med Biol 1987;4:93±108. [10] Vogel P, Gabriel M, Goebel HH, Dyck PJ. Hereditary motor sensory neuropathy type II with neuro®lament accumulation: new ®nding or new disorder. Ann Neurol 1985;17:445±461. [11] Ouvrier RA. Giant axonal neuropathy. A review. Brain Dev 1989;11:207±214. [12] Gambarelli D, Hassoun J, Pellissier JF, Livet MO, Pinsard N, Toga M. Giant axonal neuropathy: involvement of peripheral nerve, mesenteric and extra neuronal area. Acta Neuropathol (Berl) 1977;39:226±261. [13] Ionasescu V, Searby CH, Rubenstein P, Sandra A, Cancilla P, Robillard J. Giant axonal neuropathy: normal protein composition of neuro®laments. J Neurol Neurosurg Psychiatry 1983;46:551±554. [14] Tandan R, Little BW, Emery ES, Good PS, Pendlebury W, Bradley WG. Childhood giant axonal neuropathy: case report and review of the literature. J Neurol Sci 1987;82:205±228. [15] Lampl Y, Eshel E, Ben-David II, Gilad R, Saravo-Pinhas I, Sandbank U. Giant axonal neuropathy: predominant central system manifestation. Dev Med Child Neurol 1992;34:164±169.
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