Overrepresentation of the proarrhythmic, sudden death predisposing sodium channel polymorphism S1103Y in a population-based cohort of African-American sudden infant death syndrome.
BACKGROUND
The S1103Y-SCN5A polymorphism has been implicated as a proarrhythmic, sudden death predisposing risk factor in African Americans, including one postmortem investigation of African-American infants with sudden infant death syndrome (SIDS).


OBJECTIVE
The purpose of this study was to assess whether the relatively African-American-specific common polymorphism S1103Y in the SCN5A-encoded cardiac sodium channel is overrepresented in SIDS among African Americans.


METHODS
Seventy-one cases from a population-based cohort of unexplained infant deaths among African Americans (37 females and 34 males, average age 3 +/- 2 months, age range birth to 11 months) were submitted to the Mayo Clinic Windland Smith Rice Sudden Death Genomics Laboratory for postmortem genetic testing. Polymerase chain reaction and a restriction digest assay were performed to genotype this cohort for S1103Y.


RESULTS
Targeted mutational analysis of exon 18 in SCN5A of the African-American SIDS cohort (n = 71) revealed the S1103Y polymorphism in 16 (22.5%) of 71 African-American cases of SIDS compared to 135 (11.6%) of 1,161 ostensibly healthy adult African Americans (P = .01).


CONCLUSIONS
This study provides an independent assessment of the prevalence of S1103Y-SCN5A among African-American infants with sudden, unexpected, unexplained death prior to their first birthday. Further scrutiny and quantification of the risk apparently associated with S1103Y appear warranted.
Van Norstrand
David W
DW
Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota 55905, USA.
Tester
David J
DJ
Ackerman
Michael J
MJ
D001741:Black or African American / Q000235:genetics; D001145:Arrhythmias, Cardiac / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009124:Muscle Proteins / Q000235:genetics; D062554:NAV1.5 Voltage-Gated Sodium Channel; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012307:Risk Factors; D015222:Sodium Channels / Q000235:genetics*; D013398:Sudden Infant Death / Q000235:genetics*
D009124:Muscle Proteins; D062554:NAV1.5 Voltage-Gated Sodium Channel; C568320:SCN5A protein, human; D015222:Sodium Channels