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Molecular genetic and clinical findings in a Friedreich’s Ataxia

Abstract

Mohamed Aziz, Yassine Oussama, Malek Chiheb and Hamza Abdou

The most common mutation in Friedreich’s ataxia (FA) is an expanded GAA trinucleotide repeat in the first intron of the FXN (Frataxin) gene. A clear correlation between the size of the expanded alleles and phenotype severity was found as the major determining factor. The objective of this study was to report clinical and molecular data of 10 patients homozygous for pathological FXN GAA expansions. Clinical evaluation was performed for all patients. GAA expansions were detected by Tripled Primed PCR (TPPCR) and GAA allele size was estimated by Long Range PCR (XL-PCR). Clinical features were variable within the same family with no correlation between age at onset, worsening score or tendon reflexes status. All patients were homozygous for the pathological GAA expansions. No obvious relationship was found between the different clinical features and size of GAA repeats. In conclusion, factor controlling phenotypic expression in FA may be related to other factors than FXN GAA expansions.

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