A case of Friedreich's ataxia confirmed by DNA-analysis.

The first case of DNA-confirmed Friedreich's ataxia in Bulgaria is presented. The results from the DNA studies of the index patient revealed two alleles with an expansion between 500 and 1500 repeats of the GAA trinucleotide in the first intron of the X25 gene. The parents had one normal allele with 7-22 repeats and one allele with a similar expansion to that of the patient in the first intron of the X25 gene. These results confirm the homozygous mode of transmission of the abnormal alleles (with an expansion of the GAA trinucleotide in the first intron of the X25 gene) from the two normal heterozygous parents to their affected offspring.