Mutation in the mitochondrial translation elongation factor EFTs results in severe infantile liver failure

Multiple respiratory chain deficiencies represent a common cause of mitochondrial diseases and often result in hepatic failure. A significant fraction of patients present mitochondrial DNA depletion but a number of cases remain unexplained. The aim of our study was to identify the disease causing gene in a kindred with intrauterine growth retardation, neonatal lactic acidosis, liver dysfunction and multiple respiratory chain deficiency in muscle.

Homozygosity mapping was performed by 50K SNP genotyping and candidate genes were successively analyzed by direct sequencing on genomic DNA of the family members.

SNP genotyping detected several regions of homozygosity in which we focused our attention to genes involved in mitochondrial translation. We sequenced the TSFM gene, encoding the mitochondrial translation factor EFTs and identified a homozygous mutation changing a highly conserved arginine into a tryptophan (R312W).

This mutation has been previously reported in two unrelated kindred presenting two distinct syndromes (fatal mitochondrial encephalomyopathy and hypertrophic cardiomyopathy respectively). The description of a third syndrome associated with a same TSFM mutation gives support to the broad clinical and genetic heterogeneity of mitochondrial translation deficiencies in human. It suggests that mitochondrial translation deficiency represents a growing cause of hepatic failure of mitochondrial origin in infants.