Analyse des manifestations oculaires associées à la néphronophtise et étude génétique chez trois familles tunisiennes

PURPOSE

Nephronophthisis is a familial interstitial nephropathy with an autosome recessive mode of transmission. In some cases, it is associated with ocular manifestations such as retinitis pigmentosa in Senior-Løken syndrome. We report ocular abnormalities and genetic results in three affected Tunisian families.

PATIENTS AND METHODS

Twenty-two members of these three families underwent a complete ophthalmologic examination (visual acuity, slit lamp biomicroscopy, ophthalmoscopy, and retinal electrophysiology). For genetic study, all individuals were genotyped and underwent a genomic sequence.

RESULTS

Twenty-two subjects, nine of whom presented nephronophthisis, were included in this study. Retinitis pigmentosa was found in three cases. Our genetic study demonstrated that patients belonging to family 1 had homozygous deletions in NPHP1, all affected individuals from family 3 were linked to NPHP4 and presented a deletion in exons 2 and 3. Results are pending for patients in family 2.

CONCLUSION

Senior-Løken syndrome is a rare hereditary disease that combines familial juvenile nephronophthisis and retinitis pigmentosa. This association was described in the literature in 39%-43% of cases. In our study, it was approximately 33% of cases. The genetic study can sometimes obviate the need for renal puncture, especially when the homozygous deletion of NPHP1 gene is confirmed.

Phenotype and sarcoglycan expression in Tunisian LGMD 2C patients sharing the same del521-T mutation

Limb-girdle muscular dystrophy type 2C is an autosomal recessive muscular disorder caused by mutations in the gene encoding the gamma-sarcoglycan subunit. This gamma-sarcoglycanopathy is prevalent in Tunisia where only one homozygous mutation a 521-T deletion has been identified. The aim of this study was to carry out a comparative clinical and immunocytochemical analysis of Tunisian patients sharing the same gamma-sarcoglycan gene mutation. One hundred and thirty-two patients were classified as severe, moderate or mild according to a calculated severity score. Heterogeneous phenotypes between siblings were encountered in 75% of the families. The severity of the disease was not found to be related to the age of onset. Immunohistochemical studies of muscle biopsy showed a total absence of gamma-sarcoglycan, a normal or slightly reduced alpha and delta-sarcoglycans whereas the expression of beta-sarcoglycan was variable. The residual sarcoglycan expression was not related to the clinical phenotype. In conclusion, the phenotypic variability in sarcoglycanopathies in Tunisia seems to involve a modifying gene controlling the course of the disease.

Effect of vitamin E supplementation in patients with ataxia with vitamin E deficiency

Ataxia with vitamin E (Vit E) defciency (AVED) is an autosomal recessive disorder caused by mutations of the alpha tocopherol transfer protein gene. The Friedreich ataxia phenotype is the most frequent clinical presentation. In AVED patients, serum Vit E levels are very low in the absence of intestinal malabsorption. As Vit E is a major antioxidant agent, Vit E deficiency is supposed to be responsible for the pathological process. Twenty-four AVED patients were fully investigated (electromyography, nerve conduction velocity (NVC) studies, somatosensory evoked potentials, cerebral computed tomography scan, sural nerve biopsy, genetic studies) and supplemented with Vit E (800 mg daily) during a 1-year period. Clinical evaluation was mainly based on the Ataxia Rating Scale (ARS) for cerebellar ataxia assessment and serum Vit E levels were monitored. Serum Vit E levels normalized and ARS scores decreased moderately but significantly suggesting clinical improvement. Better results were noted with mean disease duration < or = 15 years. Reflexes remained abolished and posterior column disturbances unchanged. Vitamin E supplementation in AVED patients stabilizes the neurological signs and can lead to mild improvement of cerebellar ataxia, especially in early stages of the disease.

Linkage of a new locus for autosomal recessive axonal form of Charcot-Marie-Tooth disease to chromosome 8q21.3

We report the clinical and genetic linkage analysis of a large Tunisian family with thirteen affected patients suffering from Charcot-Marie-Tooth disease with pyramidal involvement. The inheritance is autosomal recessive. The clinical phenotype is consistent in all patients. It is characterized by onset during the first decade, a progressive course and distal atrophy in all four limbs, associated with a mild pyramidal syndrome. Nerve biopsy in two patients showed severe axonal neuropathy. Genetic linkage excluded known loci of different genetic forms of Charcot-Marie-Tooth disease, familial spastic paraplegia and familial amyotrophic lateral sclerosis. A significant lod score was obtained with marker D8S286, confirming linkage to chromosome 8q21.3. The clinical syndrome observed in this family seems to correspond to a new genetic form of autosomal recessive Charcot-Marie-Tooth disease.

Novel mutations in spastin gene and absence of correlation with age at onset of symptoms

Autosomal dominant hereditary spastic paraplegia is genetically heterogeneous, with at least five loci identified by linkage analysis. Recently, mutations in spastin were identified in SPG4, the most common locus for dominant hereditary spastic paraplegia that was previously mapped to chromosome 2p22. We identified five novel mutations in the spastin gene in five families with SPG4 mutations from North America and Tunisia and showed the absence of correlation between the predicted mutant spastin protein and age at onset of symptoms.

Giant axonal neuropathy locus refinement to a < 590 kb critical interval

Giant axonal neuropathy (GAN) is a rare autosomal recessive neurodegenerative disorder, characterised clinically by the development of chronic distal polyneuropathy during childhood, mental retardation, kinky or curly hair, skeletal abnormalities and, ultrastructurally, by axons in the central and peripheral nervous systems distended by masses of tightly woven neurofilaments. We recently localised the GAN locus in 16q24.1 to a 5-cM interval between the D16S507 and D16S511 markers by homozygosity mapping in three consanguineous Tunisian families. We have now established a contig-based physical map of the region comprising YACs and BACs where we have placed four genes, ten ESTs, three STSs and two additional microsatellite markers, and where we have identified six new SSCP polymorphisms and six new microsatellite markers. Using these markers, we have refined the position of our previous flanking recombinants. We also identified a shared haplotype between two Tunisian families and a small region of homozygosity in a Turkish family with distant consanguinity, both suggesting the occurrence of historic recombinations and supporting the conclusions based on the phase-known recombinations. Taken together, these results allow us to establish a transcription map of the region, and to narrow down the GAN position to a < 590 kb critical interval, an important step toward the identification of the defective gene.

A new locus for autosomal recessive limb-girdle muscular dystrophy in a large consanguineous Tunisian family maps to chromosome 19q13.3

Autosomal recessive limb-girdle muscular dystrophies represent a genetically heterogeneous group of diseases characterized by a progressive involvement of skeletal muscles. They show a wide spectrum of clinical courses, varying from very mild to severe. Eight loci responsible for autosomal recessive limb-girdle muscular dystrophies have been mapped and six defective genes identified. In this study, we report the clinical data, muscle biopsy findings and results of genetic linkage analysis in a large consanguineous Tunisian family with 13 individuals suffering from autosomal recessive limb-girdle muscular dystrophy. Clinical features include variable age of onset, proximal limb muscle weakness and wasting predominantly affecting the pelvic girdle, and variable course between siblings. CK rate was usually high in younger patients. Muscle biopsy showed dystrophic changes with normal expression of dystrophin and various proteins of the dystrophin-associated protein complex (sarcoglycan sub-units, dystroglycan, and sarcospan). Genetic linkage analysis excluded the known limb-girdle muscular dystrophies loci as well as ten additional candidate genes. A maximum LOD score of 4.36 at &theta;=0.00 was obtained with marker D19S606, mapping this new form of autosomal recessive limb-girdle muscular dystrophy to chromosome 19q13.3.

Clinical and genetic study of familial Parkinson's disease in Tunisia

OBJECTIVE

To determine inheritance patterns and clinical characteristics of familial PD (F-PD) in Tunisia.

METHODS

Twenty-one index patients were selected on the basis of typical PD and a family history of PD. The 21 families of the index patients were visited at home, and clinical assessment of all available relatives, a total of 133 individuals, was made. Extensive pedigree data detected 67 additional cases. We ascertained medical history, age, age at onset, first sign at onset, course of the disease, dosage and duration of levodopa (LD) treatment, and associated diseases. One patient from each family was hospitalized to confirm response to LD by evaluation of untreated and treated Unified Parkinson's Disease Rating Scale scores. The sex ratio, transmission pattern, ancestral secondary cases, and segregation ratio (SR) were determined by pedigree analysis.

RESULTS

Eighty-eight patients were analyzed (44 men and 44 women; mean age at onset, 39.8 +/- 14.4 years). Pedigree analysis showed 10 single-generation (SG) families (i.e., all affected members belonging to 1 generation) and 11 multigenerational (MG) families (i.e., affected members spanning >1 generation). Parental consanguinity was more frequent in SG families than in MG families. The SR in SG families was 0.23 +/- 0.05, compatible with autosomal recessive (AR) inheritance. Analysis of MG pedigrees showed autosomal dominant (AD) inheritance with reduced penetrance in 9 of 10 families. Age at onset was younger than in sporadic PD. Intrafamilial variability of age at onset, symptom of onset, and clinical course was observed. There was no difference in clinical characteristics between SG and MG families apart from dystonic foot at onset, which was more frequent in SG families.

CONCLUSIONS

First, F-PD is clinically similar to sporadic PD apart from younger age at onset. Second, there is intrafamilial and interfamilial variability of all clinical features. Third, F-PD in Tunisia is genetically heterogenous with at least two inheritance patterns: AD and AR.

Linkage to chromosome 13q11-12 of an autosomal recessive cerebellar ataxia in a Tunisian family

OBJECTIVE

To report the clinical findings and the genetic linkage mapping of an autosomal recessive cerebellar ataxia associated to peripheral neuropathy, showing an early onset cerebellar ataxia with retained tendon reflexes (EOCA) phenotype.

BACKGROUND

EOCA is a clinical syndrome delimited by Harding distinguished from Friedreich's ataxia (FA) mainly by the preservation of tendon reflexes. Molecular genetic study of patients with EOCA has demonstrated genetic heterogeneity. A form of autosomal recessive spastic ataxia has been described in Charlevoix Saguenay area in Quebec (ARSACS); the gene responsible has been mapped to chromosome 13q.

METHODS

Genetic linkage analysis was performed on 18 members of a large family including 8 of 9 members with EOCA. After exclusion of FA and ataxia with vitamin E deficiency loci as well as loci of autosomal dominant cerebellar ataxias, we performed a linkage analysis to markers of 13q11-12 region.

RESULTS

The 9 affected members of this family showed stereotyped clinical features with cerebellar ataxia, pyramidal syndrome, and a variable degree of axonal peripheral neuropathy. Linkage was detected between the disease locus and the microsatellite marker D13S232. Surrounding markers to D13S232 confirmed the linkage and showed the homozygosity of the affected members.

CONCLUSION

The family reported here showed the same locus as autosomal recessive spastic ataxia Charlevoix Saguenay disease.

Identification of a new locus for autosomal recessive Charcot-Marie-Tooth disease with focally folded myelin on chromosome 11p15

Autosomal recessive Charcot-Marie-Tooth disease type 4B (CMT4B) is a demyelinating hereditary motor and sensory neuropathy characterized by abnormal folding of myelin sheaths. A locus for CMT4B has previously been mapped to chromosome 11q23 in a southern Italian pedigree. We initially excluded linkage in two Tunisian families with CMT4B to chromosome 11q23, demonstrating genetic heterogeneity within the CMT4B phenotype. Subsequently, using homozygosity mapping and linkage analysis in the largest Tunisian pedigree, we mapped a new locus to chromosome 11p15. A maximum two-point lod score of 6.05 was obtained with the marker D11S1329. Recombination events refined the CMT4B locus region to a 5.6-cM interval between markers D11S1331 and D11S4194. The second Tunisian CMT4B family was excluded from linkage to the new locus, demonstrating the existence of at least a third locus for the CMT4B phenotype.

Localization of alpha-tocopherol transfer protein in the brains of patients with ataxia with vitamin E deficiency and other oxidative stress related neurodegenerative disorders

Vitamin E (alpha-tocopherol) is an essential nutrient and an important antioxidant. Its plasma levels are dependent upon oral intake, absorption and transfer of the vitamin to a circulating lipoprotein. The latter step is controlled by alpha-tocopherol transfer protein (alpha-TTP), which is a 278 amino acid protein encoded on chromosome 8, known to be synthesized in the liver. Mutations in alpha-TTP are associated with a neurological syndrome of spinocerebellar ataxia, called ataxia with vitamin E deficiency (AVED). Earlier studies suggested that alpha-TTP is found only in the liver. In order to establish whether alpha-TTP is expressed in the human brain, and what relationship this has to AVED, we studied immunohistochemically the presence of alpha-TTP in the brains of a patient with AVED, normal subjects, and patients with Alzheimer's disease (AD), Down's syndrome (DS), cholestatic liver disease (CLD) and abetalipoproteinemia (ABL). The neuropathology of both AD and DS is thought to be related in part to oxidative stress. The diseases of AVED, of cholestatic liver disease, and of abetalipoproteinemia are thought to be due to lack of circulating tocopherol, leading to inadequate protection against oxidative damage. We demonstrate the presence of alpha-TTP in cerebellar Purkinje cells in patients having vitamin E deficiency states or diseases associated with oxidative stress.

Fine localization of the CMT4A locus using a PAC contig and haplotype analysis

Charcot-Marie-Tooth disease type 4A (CMT4A) is a severe, autosomal recessive peripheral neuropathy linked to chromosome 8q13-q21. We have previously constructed a YAC contig across the CMT4A region and narrowed the disease-flanking interval to approximately three megabases. Subsequently, we constructed a PAC/BAC contig made of 44 clones and mapped 44 new and 30 previous STSs, ESTs, and polymorphic makers to the region. Using 13 polymorphic markers, we have now identified an ancestral haplotype segregating in three families, indicating a common founder mutation. Two ancestral recombination events in this haplotype significantly reduce the minimal candidate region to a minimal trailing path of five PAC/BAC clones, which will now allow direct investigation of candidate genes for CMT4A.

Linkage of a commoner form of recessive amyotrophic lateral sclerosis to chromosome 15q15-q22 markers

Autosomal recessive familial amyotrophic lateral sclerosis (RFALS) is a rare form of ALS that usually presents at an early age with slow progression of symptoms. RFALS is clinically and genetically heterogeneous and the locus of RFALS type 3 was mapped to 2q33 (ALS2) in a single family. We now report linkage of a more-common form of RFALS to chromosome 15q15-q22 markers (ALS5) and show further genetic locus heterogeneity in RFALS. ALS5 is the locus for most families with RFALS and appears to be present in both North African and European populations.

A clinicopathological observation of Nyssen-van Bogaert syndrome with second motor neuron degeneration: two distinct clinical entities

OBJECTIVES

To report a novel clinicopathological observation of Nyssen-van Bogaert syndrome. To compare this observation with those previously reported. To discuss the nosological entity of this syndrome. To define the exact etiopathogenic mechanism of the neurogenic amyotrophy occurring at the late stage of the disease.

MATERIALS AND METHODS

The patient was a 16-year-old girl who developed loss of vision and deafness at the age of 8. Ataxia with slight cerebellar signs were present by the age of 14. Over the next 2 years, she developed distal weakness and wasting of the legs with depressed ankle reflexes. She died at the age of 16. Deparaffinized sections of the brain, the brain stem, the cerebellum and the spinal cord were stained with haematoxylin & eosin (H&E), Nissl, Woelcke, Bodian, periodic acid-schiff (PAS), Sudan Black and Kluver Barera. Antibodies anti-GFAP, anti-MPB and anti-neurofilaments were used for immunohistochemical stainings following the avidin-biotin-peroxydase complex (ABC) methods.

RESULTS

The clinical pictures in our patient are similar to those previously reported in juvenile patients with optico-cochleo-dentate syndrome. Pathological study of the nervous system confirmed the diagnosis of Nyssen-van Bogaert syndrome and also showed a severe anterior horn, posterior horn and Clarke's column nerve cell degeneration with anterior root atrophy.

CONCLUSION

From these clinical and pathological data, the authors suggest to include Nyssen-van Bogaert syndrome among the group of multiple system atrophy, propose to divide this syndrome into 2 forms (an early infantile form and a juvenile form) and consider that the neurogenic amyotrophy occurring at the late stage of the disease in juvenile and adult patients is mainly caused by the second motor neuron involvement.

Refined mapping and characterization of the recessive familial amyotrophic lateral sclerosis locus (ALS2) on chromosome 2q33

Amyotrophic lateral sclerosis (ALS) is a progressive degenerative neuromuscular disease that shows familial, autosomal dominant inheritance in 10%-15% of cases. Previous genetic analysis of one large family linked a recessive form of familial ALS (FALS-AR type 3) to the chromosome 2q33-35 region. Using additional polymorphic markers, we have narrowed the size of the linked region to approximately 1.7 cM by linkage and haplotype analysis. We have also established a yeast artificial chromosome contig across the locus that covers an approximate physical distance of 3 million bases. Based on this contig, genes and expressed sequences that map near the 2q33 region have been examined to determine whether they are located within this ALS2 candidate locus. Five identified genes and 34 expressed sequence tags map within the region defined by crossover analysis and merit further consideration as candidate genes for this disease.

Dysferlin, a novel skeletal muscle gene, is mutated in Miyoshi myopathy and limb girdle muscular dystrophy

Miyoshi myopathy (MM) is an adult onset, recessive inherited distal muscular dystrophy that we have mapped to human chromosome 2p13. We recently constructed a 3-Mb P1-derived artificial chromosome (PAC) contig spanning the MM candidate region. This clarified the order of genetic markers across the MM locus, provided five new polymorphic markers within it and narrowed the locus to approximately 2 Mb. Five skeletal muscle expressed sequence tags (ESTs) map in this region. We report that one of these is located in a novel, full-length 6.9-kb muscle cDNA, and we designate the corresponding protein 'dysferlin'. We describe nine mutations in the dysferlin gene in nine families; five are predicted to prevent dysferlin expression. Identical mutations in the dysferlin gene can produce more than one myopathy phenotype (MM, limb girdle dystrophy, distal myopathy with anterior tibial onset).

Electrophysiology and nerve biopsy: comparative study in Friedreich's ataxia and Friedreich's ataxia phenotype with vitamin E deficiency

The authors report a comparative study of peripheral nerve conductions and nerve biopsy and somatosensory evoked potentials between 15 patients with Friedreich's ataxia and 15 patients with Friedreich's ataxia phenotype with selective vitamin E deficiency. The patients in the two groups are of similar age, age of onset, and clinical phenotype. Peripheral motor nerve action potential amplitude, and conduction velocities are within normal ranges in the two groups. In the Friedreich's ataxia group there is an early and severe peripheral sensory axonal neuronopathy, characterised by an important reduction of the amplitude of sensory action potential, and important loss of myelinated fibres with complete disappearance of large myelinated fibres without any regenerative process. In the Friedreich's ataxia phenotype with selective vitamin E deficiency group there is slight-to-moderate axonal sensory neuropathy with normal to moderate decrease of large myelinated fibre density and important regeneration in nerve biopsy. Somatosensory evoked potentials are markedly involved in the two groups asserting a severe involvement of somatosensory pathway in lumbar, thoracic and cervical spinal cord. These findings suggest that the pathological mechanism involved in the two diseases are different: central peripheral axonopathy in Friedreich's ataxia and central distal axonopathy in Friedreich's ataxia phenotype with selective vitamin E deficiency.

Methylmalonic acidaemia with bilateral globus pallidus involvement: a neuropathological study

A 16-month-old boy was hospitalized because of a 1-day history of severe ketoacidosis with lethargy, hypotonia, vomiting, and important dyspnoea. Organic acid assay by gas chromatography-mass spectrometry confirmed the diagnosis of methylmalonic acidaemia (MMA). On the sixteenth day, he developed an acute extrapyramidal disorder. The CT scan of the brain disclosed bilaterally symmetric lucency of basal ganglia. He died at 17 months of age. Post-mortem neuropathological examination, showed severe necrosis with spongiosis, cystic cavitation and numerous lipid-laden macrophages of the globi pallidi, and mild spongiosis of subthalamic nuclei, mammillary bodies, portion of internal capsule adjacent to globus pallidus, superior cerebellar peduncles and tegmentum of brainstem. Pallidal infarction, a focal ischaemic lesion, demonstrates that ischaemia/energy depletion may be important in the etiology of the neuropathology of MMA.

LGMD 2E in Tunisia is caused by a homozygous missense mutation in beta-sarcoglycan exon 3

Four of the currently recognized autosomal recessive limb-girdle muscular dystrophies (LGMD type 2C-F) are caused by mutations in the genes encoding components of the sarcoglycan complex. LGMD 2C, caused by mutations in gamma-sarcoglycan, is prevalent in northern Africa, especially in Tunisia, where this type of muscular dystrophy was originally described. Although the disease initially was assumed to be genetically homogeneous in this region, linkage to the alpha-sarcoglycan locus (LGMD 2D) has also been found. We have now identified the first Tunisian family with beta-sarcoglycanopathy (LGMD 2E), further adding to the genetic heterogeneity of autosomal recessive LGMD in this population. Direct sequencing of the beta-sarcoglycan gene revealed a homozygous mutation (G272-->T, Arg91Leu) in exon 3. This change affects the same arginine residue in the immediate extracellular domain of the protein that was mutated to a proline (G272-->C, Arg91Pro) in a Brazilian family with a severe form of the disease. Immunohistochemical analysis for the sarcoglycan complex demonstrates absence of the known components of the complex in both of these families. We postulate that the immediate extracellular domain of beta-sarcoglycan may be important for the assembly and/or maintenance of this complex, potentially mediated by disulfide-bond formation to another sarcoglycan via the single cysteine residue in that domain.

Atypical ataxia telangiectasia with early childhood lower motor neuron degeneration: a clinicopathological observation in three siblings

We report three brothers belonging to a consanguineous family and suffering from ataxia telangiectasia with severe early neurogenic amyotrophy. Pathological examination of the brain and spinal cord in one of them showed Purkinje cell loss with empty baskets and numerous axonal spheroids, dorsal column demyelination with astrocytic proliferation and severe anterior horn cell degeneration. We consider these pathological findings to be related to Louis-Bar disease. Anterior horn cell changes may be one of the early pathological features in ataxia telangiectasia.

Generation of a 3-Mb PAC contig spanning the Miyoshi myopathy/limb-girdle muscular dystrophy (MM/LGMD2B) locus on chromosome 2p13

Miyoshi myopathy (MM) and limb-girdle muscular dystrophy subtype 2B (LGMD2B) map to the same region on chromosome 2p13. To facilitate the cloning of the defective gene causing these two diseases, we used a combination of chromosome walking and expressed sequence tag (EST) screening and identified 864 P1-derived artificial chromosomes (PACs) whose inserts map to the MM/LGMD2B candidate region and surrounding areas. Among them, 139 are from a chromosome 2-specific PAC library and 725 are from a total genomic PAC library. A 3-Mb contig spanning the candidate region for MM/LGMD2B was assembled. This contig contains 200 PACs, 10 known genetic markers, 5 new polymorphic markers, 57 sequence tagged sites (STSs) generated from PAC end fragments, and 4 random STSs. In addition, we mapped 24 ESTs to this contig and excluded 37 ESTs from the contig, thus eliminating them as candidate MM/LGMD2B genes. The high-resolution, sequence-ready PAC contig for the MM/LGMD2B region provides a backbone for the identification of the disease gene(s) and for clarification of the relationship between the two diseases.

Homozygosity mapping of giant axonal neuropathy gene to chromosome 16q24.1

Giant axonal neuropathy (GAN) is a rare autosomal recessive disorder described as a symmetrical distal neuropathy, with peripheral axons dilated by accumulation of 10 nm neurofilaments (NF) and a severe course of the disease. The observation of kinky or curly hairs is not a constant finding. The GAN1 locus was localized by homozygosity mapping to chromosome 16 q24.1 in a 3 (4) cM interval flanked by the markers D16S3073 and D16S505 (D16S511) in three non-related Tunisian families, showing a genetic homogeneity in these families. Two point lod-score calculation between the linked haplotype and the disease locus was 14.2 at theta(max) = 0. The patients share a slow course of the disease. The differences in the course of the disease between Tunisian and non-Tunisian patients suggest a possible genetic heterogeneity, which is why the present linkage has been referred to as GAN1. The biochemical defect in GAN1 should help to understand the mechanisms involved in NF accumulations as in other neurological diseases (ALS, SMA).

Friedreich's ataxia with isolated vitamin E deficiency: a neuropathological study of a Tunisian patient

The neuropathological findings in a Tunisian patient with Friedreich's ataxia with vitamin E deficiency are reported. The main histological changes are: (1) spinal sensory system demyelination with neuronal atrophy, axonal spheroids and corpora amylacea; (2) neuronal lipofuscin accumulation in the third cortical layer of the cerebral cortex, thalamus, lateral geniculate body, twelfth and ambiguus nuclei, spinal horns and posterior root ganglia. Ultrastructurally, the lipopigments were of uniform granularity without lipid droplets.

International Cooperative Ataxia Rating Scale for pharmacological assessment of the cerebellar syndrome. The Ataxia Neuropharmacology Committee of the World Federation of Neurology

Despite the involvement of cerebellar ataxia in a large variety of conditions and its frequent association with other neurological symptoms, the quantification of the specific core of the cerebellar syndrome is possible and useful in Neurology. Recent studies have shown that cerebellar ataxia might be sensitive to various types of pharmacological agents, but the scales used for assessment were all different. With the long-term goal of double-blind controlled trials-multicentric and international-an ad hoc Committee of the World Federation of Neurology has worked to propose a one-hundred-point semi-quantitative International Cooperative Ataxia Rating Scale (ICARS). The scale proposed involves a compartimentalized quantification of postural and stance disorders, limb ataxia, dysarthria and oculomotor disorders, in order that a subscore concerning these symptoms may be separately studied. The weight of each symptomatologic compartment has been carefully designed. The members of the Committee agreed upon precise definitions of the tests, to minimize interobserver variations. The validation of this scale is in progress.

Limb-girdle muscular dystrophy 2C: clinical aspects

The LGMD2C linked to chromosome 13q and related to a 35 KDa dystrophin-associated glycoprotein deficiency, is very similar to Duchenne muscular dystrophy with an autosomal recessive inheritance. It is characterized by a variability of the age of onset, the severity of the evolution and the severity of myopathic changes at the muscle biopsy. This variability was also present in the expression of the alpha-sarcoglycan between the same sibships and between different families.

Recessive Schwartz-Jampel syndrome (SJS): confirmation of linkage to chromosome 1p, evidence of genetic homogeneity and reduction of the SJS locus to a 3-cM interval

Schwartz-Jampel syndrome (SJS), or chondrodystrophic myotonia, is a rare autosomal recessive disorder characterized by generalized myotonia resulting in a particular, recognizable facies and osteoarticular abnormalities. Some of us have recently shown genetic linkage of SJS to a locus on 1p34-p36.1 in five families. Here, we show by homozygosity mapping and segregation analysis that eight new families are most likely linked to the SJS locus on chromosome 1, confirming the localization of SJS to chromosome 1p and suggesting genetic homogeneity. Recombination events reduced the SJS locus from a genetic interval of 8 to 3 cM, which should facilitate the identification of the SJS gene. Low clinical variability was observed between the studied families, except for osteoarticular abnormalities. Since the severity and the location of osteoarticular abnormalities varied from one individual to another, even in the same families, other factors than the SJS gene itself, genetic or epigenetic, might contribute to the phenotype.