Eldomery et al. (Genome Medicine (2016) 8:106) recently described a new mechanism of mitochondrial disease underlying a phenotype of left ventricular non-compaction, hypotonia and early death. Four affected individuals were found via whole exome sequencing to have compound heterozygous or homozygous pathogenic variants in a gene called MIPEP. This gene encodes for MIP, a mitochondrial peptidase responsible for processing some nuclear encoded mitochondrially targeted proteins. Because the MIP peptidase processes about 25% percent of these preproteins, a widespread mitochondrial dysfunction is expected.

Hilary Vernon, MD PhD