OPA1 and autosomal dominant optic atrophy: However, mtDNA proliferation was once reported in leukocytes of patients with dominant optic atrophy and OPA1 mutations; this result could be due, as suggested by the Authors, to the relatively short half-life of circulating leukocytes and their rapid turnover, which preclude the formation and subsequent clonal expansion of somatic mtDNA abnormalities (Sitarz et al., 2012).