Recessive missense variants in TSFM have been reported to result in mitochondrial translation deficiency [14], [15] and Finnish mitochondrial disease patients from two families have been identified with compound heterozygosity of this nonsense variant (each with a different second hit in TSFM) (personal communication) - lending strong evidence to the hypothesis that complete loss of this gene is not tolerated in humans. The gene discussed is TSFM; the disease is inborn mitochondrial metabolism disorder.