A new mitochondrial DNA deletion associated with diabetic amyotrophy, diabetic myoatrophy and diabetic fatty liver

Abstract

Mitochondrial dysfunctions of the muscle in diabetic amyotrophy and of the liver in diabetic fatty liver have been reported. We investigated mitochondrial gene mutations in three cases: (1) a patient with diabetic amyotrophy in the muscles of the lower extremities, and neuropathy; (2) 5 diabetics with myoatrophy, diabetic nephropathy, and chronic renal failure; and (3) an IDDM patient with a diabetic fatty liver. We identified a 5778-bp deletion (8214-13991) in mitochondrial DNA from the muscle and liver biopsy specimens by the primer shift PCR and PCR-direct sequence methods. It is speculated that 5778-bp deletion is due to homogeneous recombination in the 7-bp repeat sequence of TCCTAGA flanking the region deleted in the mitochondrial DNA. Determination of respiratory chain enzyme activities in fresh muscle mitochondria demonstrated the defect in complex I activity. The deletion covers areas coding ND3, ND4, ND4L, and ND5 in complex I. The 5778-bp deletion might cause a defect in mitochondrial oxidative phosphorylation and contribute to the pathogenesis of diabetic amyotrophy, myoatrophy with diabetic nephropathy, and chronic renal failure, as well as diabetic fatty liver in IDDM.