This is a large international, collaborative study that reviews both the clinical and frataxin protein differences among 111 individuals with FA who are compound heterozygous for a point mutation on one gene and a GAA repeat expansion on the other FXN gene. Frataxin mutations were examined using structural modeling, stability analyses and systematic literature review. Mean age of onset and the presence of cardiomyopathy and diabetes mellitus were compared using regression analyses. In compound heterozygotes, expression of partially functional mutant frataxin delays age of onset and reduces diabetes mellitus, compared to those with no frataxin expression from the non-expanded allele. This integrated analysis of categorized frataxin mutations and their correlation with clinical outcome provides a definitive resource for investigating disease pathogenesis in FRDA.

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