ncreased Prevalence 12308 A > G mutation in Mitochondrial tRNALeu (CUN) Gene Associated with earlier Age of Onset in Friedreich Ataxia

ObjectiveFriedreich ataxia (FRDA) is an inherited recessive disorder. Mitochondrial DNA is a candidate modifying factor for FRDA.The purpose of this study was to investigate the relationship between the tRNALeu (CUN) 12308 A> G mutation and age of onset in Friedreich ataxia.Materials & MethodsThe 12308 A> G substitution in mitochondrial tRNALeu (CUN) was examined in DNA samples from 30 Friedreich ataxia patients and 48 control subjects by temporal temperature gradient gel electrophoresis (TTGE) and sequencing. Logistic regression was used to determine of cutoff age of onset.ResultsTwenty-two patients had the 12308 A> G mutation, and we found that its overall prevalence was significantly higher in 20 patients aged 17 years or younger than in 2 patients aged over 17 years (90% versus 10%). The 12308 A> G mutation lies in a region that has been highly conserved between species.ConclusionOur results show that the 12308 A > G mutation is associated with earlier age of onset in Friedreich ataxia. Thus, this mutation might cause the younger age of onset in FRDA.