Genetic Study of GAA Trinucleotide Repeats in Egyptian Patients with Friedrich Ataxia
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- Category: Vol. 78, December 2010
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Genetic Study of GAA Trinucleotide Repeats in Egyptian Patients with Friedrich Ataxia,SOMAIA ISMAIL, TAMER AMMAR, TAREK SALMAN and HANAN AFIFI
Abstract
Friedrich Ataxia (FA) is the most common cause of inherited Ataxia in Caucasian population. It is an autosomal recessive disorder caused mostly by expansion of GAA trinu-cleotide repeats in intron 1 of the frataxin gene on 9q13. The normal GAA allele in different populations ranges from 7-33 repeats while patients with friedrich Ataxia show large expan-sion ranging from 66-1700 repeats. The main aim of this study was to determine the size of GAA repeats in Egyptian patients with FA. The study included 17 patients clinically diagnosed with the disease as well as a control group of 24 unrelated healthy individuals. Long-Range PCR amplification of intron 1 of the frataxin gene was carried out using two sets of primers (one for normal alleles and one for expanded alleles). Amplified PCR products were then separated on 2% agarose gel electro-phoresis. Five out of the 17 patients (30%) showed large expansion of the GAA repeats (527-850) with mean GAA size 725±179. On the other hand, the other 12 patients showed normal size GAA as the control group (4-23) with mean size of 12±6. To our knowledge this is the first study to be done in Egypt to determine the GAA expansion in patients with FA showing that one third of patients with FA has large expansion of the GAA repeats in the frataxin gene.