Older mothers are not at risk of having grandchildren with sporadic mtDNA deletions

Single large-scale mitochondrial DNA deletions account for a quarter of mitochondrial disease cases and occur sporadically with unknown risk factors. Mitochondrial DNA deletions accumulate with age in many tissues. Primordial germ cells, the precursors of oocytes are made by our grandmothers, therefore we wanted to determine whether age of maternal grandmother is a risk factor for sporadic mitochondrial DNA deletions.