• Barry London, Michael Michalec, Haider Mehdi, Xiaodong Zhu, Laurie Kerchner, Shamarendra Sanyal, Prakash C Viswanathan, Arnold E Pfahnl, Lijuan L Shang, Mohan Madhusudanan, Catherine J Baty, Stephen Lagana, Ryan Aleong, Rebecca Gutmann, Michael J Ackerman, Dennis M McNamara, Raul Weiss, and Samuel C Dudley.
• Cardiovascular Institute, University of Pittsburgh Medical Center, Scaife S-572, 200 Lothrop St, Pittsburgh, PA 15213-2582, USA. londonb@upmc.edu
• Circulation. 2007 Nov 13; 116 (20): 2260-8.

BackgroundBrugada 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.Methods And ResultsWe 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<0.005). Wild-type GPD1-L localized near the cell surface to a greater extent than A280V GPD1-L. Coexpression of A280V GPD1-L with SCN5A reduced SCN5A cell surface expression by 31+/-5% (P=0.01).ConclusionsGPD1-L is a novel gene that may affect trafficking of the cardiac Na+ channel to the cell surface. A GPD1-L mutation decreases SCN5A surface membrane expression, reduces inward Na+ current, and causes Brugada syndrome.

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