FRIEDREICHS-ATAXIA - AUTOSOMAL RECESSIVE DISEASE CAUSED BY AN INTRONIC GAA TRIPLET REPEAT EXPANSION

Friedreich's ataxia (FRDA) is an autosomal recessive, degenerative dis ease that involves the central and peripheral nervous systems and the heart. A gene, X25, was identified in the critical region for the FRDA locus on chromosome 9q13. The gene encodes a 210-amino acid protein, frataxin, that has homologs in distant species such as Caenorhabditis elegans and yeast. A few FRDA patients were found to have point mutati ons in X25, but the majority were homozygous for an unstable GAA trinu cleotide expansion in the first X25 intron.