Objective: Our aim was to determine the clinical, genetic and radiological characteristics of spinocerebellar ataxias (SCA) in a Tunisian cohort.

Background: SCA is a heterogenous group of neurodegenerative ataxic disorders with an autosomal dominant inheritance.

To date, a few Tunisian studies have been conducted in these diseases.

Method: A descriptive retrospective study was conducted in the neurology department of National Institute Mongi Ben Hamida of Neurology of Tunis. Patients diagnosed with cerebellar ataxia having a familial history of similar cases in at least three consecutive generations were included.

Demographic, clinical and radiological data were assessed. Molecular diagnosis of SCA included simple PCR and fragment analysis looking for polyglutamine expansions (SCA 1,2,3 and 7).

Results: Nineteen patients were enrolled, including two sibling pairs. Molecular diagnosis was positive for SCA2 in nine patients and SCA7 in one patient. Diagnostic SCA panel was negative in nine patients (47.4%). Sex ratio was 1.25. Consanguinity was found in 33.3% of cases. Mean age at onset was 33.72 years ± 13.85. The mean anticipation in our cohort was 17.33 years. It was greater in paternal transmission than in maternal transmission. Inaugural symptoms were gait impairment (n=11), dysarthria (n=6) and tremor (n=2). The most frequently associated signs were parkinsonism (SCA2: n=1, SCA7: n=1), cognitive impairment (SCA2: n=1), nystagmus (SCA2 : n=1), chorea (SCA2 : n=1), nyctalopia (SCA2 : n=1), visual loss (SCA2 : n=3, SCA 7 : n=1), sensitive neuropathy (SCA2 : n=2), ophtalmoplegia (SCA2 : n=2), pigmentary retinitis (SCA 7: n=1). In our cohort, siblings presented with distinct age at onset and different clinical features.

Radiological features included vermis atrophy in all patients; hemispheric cerebellar atrophy (SCA2: n=7, SCA7: n=1), dentate nucleus calcification (SCA2: n=1), supra tentorial demyelinating lesions (SCA2: n=2), brain stem atrophy (SCA7 : n=1, SCA2 : n=5), hot cross bun sign (SCA2: n=2) and cervical medullar atrophy (SCA2 : n=3, SCA7: n=1).

Conclusion: Our study highlighted the intra familial variability in SCA 2 patients. The significant negativity of the genetic research shows the need to include other mutations in the panel. Further genetic studies in larger cohorts are needed to determine the clinical and genetic profile of SCA in Tunisia and North Africa.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/clinical-and-genetic-profile-of-spinocerebellar-ataxias-in-a-tunisian-cohort/