1: Professor Mongi Ben Hamida (1928-2003).
Hentati F.
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2: Phenotype and sarcoglycan expression in Tunisian LGMD 2C patients sharing the same del521-T mutation.
Kefi M, Amouri R, Driss A, Ben Hamida C, Ben Hamida M, Kunkel LM, Hentati F.
Institut National de Neurologie, Laboratoire de Neurobiologie Moleculaire, 1007 La Rabta, Tunis, Tunisia.
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.
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3: Identification of novel GDAP1 mutations causing autosomal recessive Charcot-Marie-Tooth disease.
Ammar N, Nelis E, Merlini L, Barisic N, Amouri R, Ceuterick C, Martin JJ, Timmerman V, Hentati F, De Jonghe P.
Molecular Genetics Department, Flanders Interuniversity Institute for Biotechnology (VIB), University of Antwerp (UIA), Universiteitsplein 1, B-2610, Antwerp, Belgium.
Mutations in the ganglioside-induced differentiation-associated protein 1 gene cause either autosomal recessive demyelinating Charcot-Marie-Tooth disease type 4A or autosomal recessive axonal Charcot-Marie-Tooth disease with vocal cord paresis. We sequenced the ganglioside-induced differentiation-associated protein 1 gene in 138 patients from 119 unrelated families diagnosed with either demyelinating or axonal autosomal recessive Charcot-Marie-Tooth disease. We detected six distinct mutant alleles in four families, four of which are novel. Electrophysiological studies show severely slowed motor nerve conduction velocities with severely reduced compound muscle action potentials. However, one patient had a normal conduction velocity in the ulnar nerve. Based on the electrophysiological tests, patients with ganglioside-induced differentiation-associated protein 1 mutations will therefore be classified as either axonal or demyelinating Charcot-Marie-Tooth disease. The neuropathological aspect shows a divergent pattern; nerve biopsies taken from two siblings at the same age and sharing the same ganglioside-induced differentiation-associated protein 1 gene mutation showed a dissimilar severity stage.
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4: Phenotypic features and genetic findings in sacsin-related autosomal recessive ataxia in Tunisia.
El Euch-Fayache G, Lalani I, Amouri R, Turki I, Ouahchi K, Hung WY, Belal S, Siddique T, Hentati F.
Department of Neurology, National Institute of Neurology, Tunis, Tunisia.
BACKGROUND: Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is a clinically homogenous disorder reported in Quebec caused by mutations in the SACS gene (chromosome 13q12). Recently, we identified a Tunisian kindred demonstrating linkage to the ARSACS locus. OBJECTIVE: To report clinical, neurophysiological, and nerve biopsy findings in patients with autosomal recessive cerebellar ataxia related to the SACS gene in Tunisia. PATIENTS AND METHODS: Genetic linkage analysis of patients with early-onset autosomal recessive cerebellar ataxia allowed the identification of 4 families from which 18 patients demonstrated linkage to the ARSACS locus. The patients were evaluated according to the International Cooperative Ataxia Rating Scale. Peripheral nerve conduction, sensory evoked potentials, and nerve biopsy were performed in most patients. RESULTS: The mean age at onset was 4.5 years. The clinical phenotype was stereotyped and associated with a progressive cerebellar syndrome, a pyramidal syndrome with brisk knee reflexes, and Babinski sign and absent ankle reflexes. The course of the disease varied among patients. Sensory evoked potentials showed severe posterior column involvement. Peripheral nerve investigations demonstrated axonal and demyelinating neuropathy. Four mutations, 2 missense and 2 nonsense, were found. CONCLUSION: In Tunisia, autosomal recessive cerebellar ataxia related to the SACS gene demonstrated a homogenous phenotype and heterogeneous allelic mutations.
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5: Autosomal recessive parkinsonism linked to parkin gene in a Tunisian family. Clinical, genetic and pathological study.
Gouider-Khouja N, Larnaout A, Amouri R, Sfar S, Belal S, Ben Hamida C, Ben Hamida M, Hattori N, Mizuno Y, Hentati F.
Service de Neurologie, Institut National de Neurologie, La Rabta, Tunis 1007, Tunisia. neziha.khouja@rns.tn
OBJECTIVES: To report clinical, pathological and genetic findings in a Tunisian kindred with autosomal recessive juvenile parkinsonism (AR-JP) linked to parkin gene. BACKGROUND: AR-JP has been mapped to chromosome 6q and is caused by several mutations of the parkin gene (Park 2). Pathological features in AR-JP are characterized by neuronal loss in substantia nigra (SN) without Lewy bodies (LB). PATIENTS AND METHODS: Three affected siblings with juvenile Parkinson's disease were studied. Pathological examination of the brain was performed in one of them. Linkage studies and mutation analysis of the parkin gene were performed. RESULTS: Clinical picture was characterized by the association of rest tremor, bradykinesia and rigidity. Parkinsonian signs markedly improved with levodopa treatment in the three siblings. Dystonia was observed in one patient and diurnal fluctuations of parkinsonian signs in another one. Linkage analysis showed homozygous haplotypes in patients as compared to unaffected individuals and mutation analysis of the parkin gene revealed a homozygous two-base AG deletion in exon 2 (101-102). Pathological examination of the brain in one patient showed marked loss of pigmented neurons with extraneuronal free melanin in the lateral and medial parts of the SN associated to a slight spongiosis and astrocytic gliosis. In the locus coeruleus, there was also loss of pigmented neurons without gliosis. No LB or neurofibrillary tangles were found neither by traditional nor by histo-immunological stainings. CONCLUSION: This Tunisian kindred with AR-JP linked to a micro-deletion of the parkin gene shows clinical similarities with the previously reported Japanese and European families. Pathological features of this kindred are compared to what has been reported in AR-JP families linked to large exonic deletions of this gene.
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6: Fukutin-related protein gene mutated in the original kindred limb-girdle MD 2I.
Driss A, Noguchi S, Amouri R, Kefi M, Sasaki T, Sugie K, Souilem S, Hayashi YK, Shimizu N, Minoshima S, Kudoh J, Hentati F, Nishino I.
Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry NCNP, Kodaira, Tokyo, Japan. adel@weboris.com
The authors mapped an autosomal recessive form of limb-girdle MD on chromosome 19q13.3 (LGMD2I), further narrowed down the candidate region to 1.1 Mb, and identified one new homozygous mutation in the fukutin-related protein (FKRP) gene on patients of the original Tunisian family. Immunohistochemical and immunoblot analysis showed abnormal expression of alpha-dystroglycan and laminin-alpha2 supporting the hypothesis that FKRP has a role in the interaction between the extracellular matrix components.
