Mutations in the same gene can result in dissimilar clinical presentations; for instance, mutations in the mitochondrially encoded MT-ATP6 gene clinically arise in different pathologies, including mitochondrial encephalomyopathy, cerebellar ataxia, severe kidney disease, and diabetes [9], neurogenic weakness, ataxia and retinitis pigmentosa (NARP) [10], and Charcot–Marie–Tooth disease [11]. The gene discussed is MT-ATP6; the disease is cerebellar ataxia.