A common mitochondrial DNA variant associated with susceptibility to dilated cardiomyopathy in two different populations

Idiopathic dilated cardiomyopathy is a recognised manifestation of mitochon drial disease due to specific mitochondrial (mt) DNA mutations. However, wh ether mtDNA polymorphisms predispose to sporadic dilated cardiomyopathy is not known. We analysed two populations with this disorder for a general mtD NA variant (T16189C), previously implicated in susceptibility to type 2 dia betes. We noted an increased frequency of the polymorphism in both populati ons compared with controls (p=0.002). The polymorphism occurred on differen t mtDNA backgrounds, suggesting that it might he a functional variant. This association of an mtDNA variant with increased susceptibility to dilated c ardiomyopathy provides evidence for a mitochondrial cause in sporadic disea se.