The m.5244G>A (p.G259S) variant in MT-ND2 has been reported in one family (PMID: 1634041) with Leber Hereditary Optic Neuropathy (LHON), however individuals in this family also harbored other mitochondrial DNA variants also associated with LHON, making the association of this variant to the primary mitochondrial disease features in these individuals unclear. Furthermore, to our knowledge, nuclear genetic testing was not performed. There are no reports of large families with this variant segregating with disease. There are no reported de novo occurrences of this variant to our knowledge. The computational predictor MitoTIP suggests this variant is pathogenic (77 percentile, PP3). This variant is absent in the GenBank dataset, Helix dataset, and gnomAD v3.1.2 (PM2_supporting). In summary, this variant meets criteria to be classified as uncertain significance 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 October 9, 2023. Mitochondrial DNA-specific ACMG/AMP criteria applied (PMID: 32906214): PM2_supporting, PP3.