Clinical and molecular genetic findings in a Friedreich’s Ataxia Tunisian family

Abstract

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 preformed for all the patients. 
GAA expansions were detected by Tripled Primed PCR (TP-PCR) 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