Background: Friedreich ataxia is the most common inherited ataxia in Europe and is mainly caused by biallelic pathogenic expansions of the GAA trinucleotide repeat in intron 1 of the FXN gene that lead to a decrease in frataxin protein levels. Rarely, affected individuals carry either a large intragenic deletion or whole-gene deletion of FXN on one allele and a full-penetrance expanded GAA repeat on the other allele.
Case presentation: We report here a patient that presented the typical clinical features of FRDA and genetic analysis of FXN intron 1 led to the assumption that the patient carried the common biallelic expansion. Subsequently, parental sample testing led to the identification of a novel intragenic deletion involving the 5'UTR upstream region and exons 1 and 2 of the FXN gene by MLPA.
Conclusions: With this case, we want to raise awareness about the potentially higher prevalence of intragenic deletions and underline the essential role of parental sample testing in providing accurate genetic counselling.
Keywords: Biallelic expansion; Deletion; FXN; Friedreich ataxia (FRDA); Parental testing.
© 2023. The Author(s).