PDHX and pyruvate dehydrogenase deficiency: This was followed by patients harboring pathogenic MT‐ATP6 gene variants encoding a structural subunit of complex V (5.9; SD = 8.1, 95% CI = 0–12.1), pathogenic variants in PDHA1 and PDHX, genes causing pyruvate dehydrogenase deficiency (5.5; SD = 4.2, 95% CI = 0.3–10.8), variants in nuclear genes affecting complex I assembly proteins and structural subunits (2.7; SD = 4.6, 95% CI = ‐0.4 to 5.8), other nuclear genotypes (2.6; SD = 5.0, 95% CI = 0.3–5.0), and pathogenic variants affecting mtDNA‐encoded complex I subunits (1.4; SD = 1.4, 95% CI = 0.1–2.7).