Friedreich’s Ataxia: Phenotype and Genotype in Eleven Patients

Abstract

Introduction:- Friedreich’s ataxia is anautosomal recessive disease due to a mutationin gene X25. This gene codes for frataxin and itis located on chromosome 9. The disease iscaused by a triplet particular sequence of bases(GAA). Normally, the GAA sequence is repeated 7 to 22 times, but in people with Friedreich’sataxia, it can be repeated hundreds or even overthousand times.Objectives:To determine if there is a correlationbetween clinical and molecular findingsin our FRDA patients.Methods: Eleven patients with the typicalFriedreich´s ataxia phenotype were studied byPCR we determined the size of the GAA expansions,and analyzed the correlation of age at onset andrate of disease progression with the number ofGAA repetitions.Results and conclusions: Molecular analysisby PCR showed eight homozygous patientsfor the expansion and three negative. The averageof the size of the expansions in the allelewas of 622±5 with an average in the age ofbeginning of 13±8. For the sample size, therewas no significant statistical correlation betweenthe age of beginning of the disease and thenumber of repetitions, although there was likean inverse correlation.Besides understanding of FRDA physiology andthe Harding clinical inclusion criteria, moleculardiagnosis is an important step in the achievementof an optimal therapeutic treatment.

Keywords

• Friedreich ataxia
• GAA repeats
• risk allele