Friedreich's ataxia and other hereditary ataxias in Greece: An 18-year perspective

Limited data exist on the spectrum of heredoataxias in Greece, including the prevalence and phenotype of Friedreich's ataxia (FRDA) and the prevalence and subtypes of dominant spinocerebellar ataxias (SCAs). We analyzed clinically and investigated genetically for FRDA and triplet-repeat expansion SCAs a consecutive series of 186 patients with suspected heredoataxia referred to Athens over 18 years. For prevalence estimates we included patients with molecular diagnosis from Cyprus that were absent from the Athens cohort. The minimum prevalence of FRDA was ~ 0.9/100,000, with clusters of high prevalence in Aegean islands. FRDA was diagnosed in 73 probands. The genotypic and phenotypic spectrum of FRDA was similar to other populations, with one patient compound heterozygote for a known point mutation in FXN (Asn146Lys). Undiagnosed recessive ataxias included FRDA-like and spastic ataxias. The minimum prevalence of dominant SCAs was ~ 0.7/100,000. SCA1 (4), SCA7 (4), SCA2, SCA6, and SCA17 (1 each) probands were identified. A molecular diagnosis was reached in 31% of dominant cases. Undiagnosed dominant patients included a majority of type III autosomal dominant cerebellar ataxias. FRDA is the commonest heredoataxia in the Greek population with prevalence towards the lower end of other European populations. Dominant SCAs are almost as prevalent. SCA1, SCA2, SCA6, SCA7 and SCA17 patients complete the spectrum of cases with a specific molecular diagnosis.