Genome-Wide Scan Identifies Variant in TNFSF13 Associated with Serum IgM in a Healthy Chinese Male Population

IgM provides a first line of defense during microbial infections. Serum IgM levels are detected routinely in clinical practice. And IgM is a genetically complex trait. We conducted a two-stage genome-wide association study (GWAS) to identify genetic variants affecting serum IgM levels in a Chinese population of 3495, including 1999 unrelated subjects in the first stage and 1496 independent individuals in the second stage. Our data show that a common single nucleotide polymorphism (SNP), rs11552708 located in the TNFSF13 gene was significantly associated with IgM levels (p=5.00x10(-7) in first stage, p=1.34x10(-3) in second stage, and p=4.22x10(-9) when combined). Besides, smoking was identified to be associated with IgM levels in both stages (P<0.05), but there was no significant interaction between smoking and the identified SNP (P>0.05). It is suggested that TNFSF13 may be a susceptibility gene affecting serum IgM levels in Chinese male population.