COX7B

Molecular characteristics

Only four patients (1 familiar case in which both the daughter and the mother were affected and two sporadic cases) have been described to date with mutations in this gene. The mutations include a 1 base pair deletion and a splicing mutation both resulting in a premature truncation of the protein (sporadic cases) and a nucleotide substitution causing a nonsense mutation (familiar case). The mutations are predicted to act with a loss of function mechanism. Molecular testing is available and recommended when the diagnosis is suspected. The diagnosis is based on sequencing of the coding regions (including sites involved in splicing) and dosage analysis of negative cases (females) to detect genomic rearrangements although none have been described to date. Differential diagnosis with LSDMCA1 and LSDMCA3 should also be considered in negative cases.