Combined Oxidative Phosphorylation Deficiency 31, also known as lethal left ventricular non-compaction-seizures-hypotonia-cataract-developmental delay syndrome, is related to 3-methylglutaconic aciduria with deafness, encephalopathy, and leigh-like syndrome and 3-methylglutaconic aciduria, type i. An important gene associated with Combined Oxidative Phosphorylation Deficiency 31 is MIPEP (Mitochondrial Intermediate Peptidase), and among its related pathways/superpathways are Peroxisomal lipid metabolism and 13q12.12 copy number variation. Affiliated tissues include eye, and related phenotypes are failure to thrive and hypotonia