SSBP1 and Leigh syndrome: The second-highest-rank variant, c.320G>A (p. [Arg107Gln]), in the SSBP1 gene has been reported as an autosomal dominant mutation associated with optic atrophy disorder and severe and progressive mitochondrial disease manifestations across the full Pearson, Kearns–Sayre, and Leigh syndrome spectrum [17,25,26,27].