Mitochondrial complex deficiency by novel compound heterozygous variants and correlation with developmental delay, undescended testicle, and left ventricular noncompaction in a Japanese patient: A case report.

We identified novel compound heterozygous variants in a Japanese patient who had hyperlactacidemia, metabolic acidosis, hyperalaninemia, developmental delay, undescended testicle, and left ventricular noncompaction. The urinary organic acids profile revealed elevated levels of 3-MGA, and BN-PAGE/Western blotting analysis and ETC. activity confirmed complex V deficiency.