Friedreich’s Ataxia: Phenotype and Genotype in Eleven Patients

Abstract

Introduction:- Friedreich’s ataxia is an autosomal recessive disease due to a mutation in gene X25. This gene codes for frataxin and it is located on chromosome 9. The disease is caused by a triplet particular sequence of bases (GAA). Normally, the GAA sequence is repeated 7 to 22 times, but in people with Friedreich’s ataxia, it can be repeated hundreds or even over thousand times. Objectives:To determine if there is a correlation between clinical and molecular findings in our FRDA patients. Methods: Eleven patients with the typical Friedreich´s ataxia phenotype were studied by PCR we determined the size of the GAA expansions, and analyzed the correlation of age at onset and rate of disease progression with the number of GAA repetitions. Results and conclusions: Molecular analysis by PCR showed eight homozygous patients for the expansion and three negative. The average of the size of the expansions in the allele was of 622±5 with an average in the age of beginning of 13±8. For the sample size, there was no significant statistical correlation between the age of beginning of the disease and the number of repetitions, although there was like an inverse correlation. Besides understanding of FRDA physiology and the Harding clinical inclusion criteria, molecular diagnosis is an important step in the achievement of an optimal therapeutic treatment.