The m.9091A>G (p.T189A) variant in MT-ATP6 was reviewed by the Mitochondrial Disease Nuclear and Mitochondrial Variant Curation Expert Panel on June 26, 2023. This variant has not been reported in the medical literature as causative in affected individuals or families with primary mitochondrial disease to our knowledge. There has been a report of this variant being present in an individual from a control cohort (PMID: 15120634). This variant has also been reported in the homoplasmic state in a family with Leber Hereditary Optic Neuropathy (from haplogroup H10) caused by the m.3733G>A variant (PMID: 22879922). There are several occurrences in population databases. The frequency in the MITOMAP GenBank sequences is 21/59,389 (0.035%). The frequency in the Helix dataset is 108/195,983 (0.055%), including 107 homoplasmic occurrences and 1 heteroplasmic occurrence, and occurring in individuals from haplogroups H, U, HV, K, and R. The frequency in gnomAD v3.1.2 is 20/56432 (0.035%), and these occurrences are homoplasmic in individuals of European and African ancestry. Furthermore, this variant has been reported in 14 out of 14 individuals in the H10 haplogroup in addition to the case described above in haplogroup H10, meeting criteria to be considered a top-level haplogroup defining variant (BA1). The computational predictor APOGEE gives a consensus rating of benign with a score of 0.28 (Min=0, Max=1), which predicts a benign effect on gene function (BP4). There are no cybrids, single fiber studies, or other functional assays reported on this variant. In summary, this variant meets criteria to be classified as benign for primary mitochondrial disease inherited in a mitochondrial manner. This classification was approved by the NICHD/NINDS U24 ClinGen Mitochondrial Disease Variant Curation Expert Panel on June 26, 2023. Mitochondrial DNA-specific ACMG/AMP criteria applied BP4, BA1.