Mitochondrial complex deficiency by novel compound heterozygous TMEM70 variants and correlation with developmental delay, undescended testicle, and left ventricular noncompaction in a Japanese patient: A case report

Key Clinical Message We identified novel compound heterozygous TMEM70 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. We identified novel compound heterozygous TMEM70 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.