Renal and cardiac biopsy findings in an adolescent patient with the 3243A>G mitochondrial DNA mutation: Favorable renal prognosis post renal transplantation from the mother.

We investigated the pathogenesis of a perihilar variant of focal segmental glomerulosclerosis detected by kidney biopsy in a 16-year-old male. The disease was refractory to steroid therapy, and at the second kidney biopsy, abnormal mitochondrial proliferation was newly observed in the podocytes. The patient also developed late-onset hearing loss and had a family history of diabetes, and genetic testing confirmed the mitochondrial DNA mutation 3243A>G (48%). Eight months after hemodialysis was started, encephalopathy occurred presumably due to rapid dehydration. After changing dialysis into continuous ambulatory peritoneal dialysis, encephalopathy was resolved, but the patient developed myocardial hypertrophy, probably because of the myocardial overreaction to congestion. A myocardial biopsy showed mitochondrial proliferation in the myocardium. After renal transplantation from his mother with a heteroplasmy of 4%, the cardiomyopathy improved, and the renal function has remained stable for 4 years. We speculated that the abnormal mitochondrial morphology in the kidney and heart may be characteristic of mitochondrial genetic disease, and renal transplantation from the mother with a low heteroplasmy was considered desirable for mitochondrial nephropathy with poor prognosis.