Mutation in glycerol-3-phosphate dehydrogenase 1-like gene (GPD1-L) decreases cardiac Na+ current and causes inherited arrhythmias

Brugada syndrome is a rare, autosomal-dominant, male-predominant form of idiopathic ventricular fibrillation characterized by a right bundle-branch block and ST elevation in the right precordial leads of the surface ECG. Mutations in the cardiac Na+ channel SCN5A on chromosome 3p21 cause approximately 20% of the cases of Brugada syndrome; most mutations decrease inward Na+ current, some by preventing trafficking of the channels to the surface membrane. We previously used positional cloning to identify a new locus on chromosome 3p24 in a large family with Brugada syndrome and excluded SCN5A as a candidate gene. We used direct sequencing to identify a mutation (A280V) in a conserved amino acid of the glycerol-3-phosphate dehydrogenase 1-like (GPD1-L) gene. The mutation was present in all affected individuals and absent in >500 control subjects. GPD1-L RNA and protein are abundant in the heart. Compared with wild-type GPD1-L, coexpression of A280V GPD1-L with SCN5A in HEK cells reduced inward Na+ currents by approximately 50% (P