Biparental inheritance of mitochondrial DNA in humans is not a common phenomenon

Purpose: A recent report has raised the possibility of biparental mitochondrial DNA (mtDNA) inheritance, which could lead to concerns by health-care professionals and patients regarding investigations and genetic counseling of families with pathogenic mitochondrial DNA variants. Our aim was to examine the frequency of this phenomenon by investigating a cohort of patients with suspected mitochondrial disease. Methods: We studied genome sequencing (GS) data of DNA extracted from blood samples of 41 pediatric patients with suspected mitochondrial disease and their parents. Results: All of the mtDNA variants in the probands segregated with their mother or were apparently de novo. There were no variants that segregated only with the father and none of these families showed evidence of biparental inheritance of their mtDNA. Conclusion: Paternal mitochondrial transmission is unlikely to be a common occurrence and therefore at this point we would not recommend changes in clinical practice.