Difference in mitochondrial DNA copy number in peripheral blood cells between probands with autism spectrum disorders and their unaffected siblings

Objectives: Several reports suggest that mitochondrial dysfunction is involved in the pathophysiology of autism spectrum disorders (ASD). Therefore, mitochondrial DNA (mtDNA) copy number, a common biomarker for mitochondrial dysfunction, might be associated with ASD phenotypes.Methods: Relative mtDNA copy number in the peripheral blood cells of 100 Korean ASD patients and their unaffected sib-pairs was measured by quantitative polymerase chain reaction (qPCR).Results: ASD patients had significantly higher relative mtDNA copy numbers than their unaffected sibs (P = .042). In addition, there were statistically significant correlations between mtDNA copy number and clinical phenotypes for language and communication in ASD.Conclusions: Our findings suggest that mitochondrial dysfunction and elevated mtDNA copy number may be a biological subtype of ASD that is related to the phenotype for communication.