MERRF (myoclonic epilepsy with ragged red fibers)
heteroplasmic mitochondrial inheritance. Results from tRNALys gene, 90% have 1 of 3 mutations, listed in order from most common to least common: 8344G->A, 8356T->C, 8363G->A. Reduces charge of tRNALys by 50%. Sx: myoclonic epilepsy, myopathy with ragged red fibers, hearing loss, ataxia, renal dysfunction, diabetes, cardiomyopathy, dementia.