Quantitative abnalysis if mittochondraial DNA deletions in myocardial biopsy samples form patients with viral myocarditis and dilated cardlimyopathy

Objective To investigate the mitochondrial DNA (mtDNA) deletions in myocardial biopsy samples in patients with viral myocarditis (VMC) and dilated cardiomyopathy (DCM),and the relation between mtDNA deletions and peripheral lymphocytes. Methods mtDNA4977 base pair (mtDNA 4977 )and mtDNA7436 base pair(mtDNA 7436 )deletion rates of myocytes and lymphocytes were measured by the method of quantitative PCR in 20 VMC patients, 12 DCM patients and 35 control cases (12 myocardial samples from the healthy cases died of accident, 23 blood samples of lymphocytes from the blood donators). Results mtDNA 4977 and mtDNA 7436 deletions were observed in both controls (0.175%) and patients with VMC (0.385%) and DCM(3.004%). The severity of mtDNA deletions in VMC and DCM cases were 1.2 and 16.2 times higher than in normal subjects. mtDNA deletion rates in patients with DCM were 6.8 times higher than that in patients with VMC ( P 0.05). The degree of mtDNA deletions in peripheral lymphocyte was similar with and showed well correlation with that in myocardium ( r =0.960, P 0.001). Conclusions mtDNA deletions in myocardium might play an important role in the pathogenesis of VMC as well as its development to DCM. The value of peripheral lymphocyte in the study of myocardial mtDNA deletion needs to be further investigated.