rs6478109

This retrospective cohort study investigated 119 Japanese Crohn's disease patients to examine whether TL1A (TNFSF15) genotype affects therapeutic outcomes with anti-TNF antibodies (infliximab and adalimumab). The TL1A -358C/C risk allele (rs6478109) was significantly associated with reduced surgery-free survival (HR 4.67, P = 0.025), with patients homozygous for the risk allele showing lower surgical-free survival compared to those carrying protective alleles. No significant differences were found in drug retention or relapse-free survival between genotypes.

This study identified rs4979462 in the TNFSF15 locus as the causal variant for primary biliary cirrhosis (PBC) susceptibility in the Japanese population through integrated analysis including case-control association (n=1279 PBC cases, n=1091 controls; P=1.85×10⁻¹⁴, OR=1.57) and in vitro functional studies. The PBC-susceptible allele generates a novel NF-1 transcription factor binding site, enhancing TNFSF15 expression and increasing susceptibility to autoimmune liver disease.

This methodological study develops ProxyGeneLD software for converting genome-wide SNP association data to pathway-enriched gene sets and validates it on multiple large GWAS datasets. The authors demonstrate successful replication of pathway enrichment for plasma HDL levels (with CETP and ABCA1 in lipid metabolism pathways) across independent samples and identify positional gene clustering as a major source of spurious enrichment in pathway analyses of GWAS data.

TNFSF15 is confirmed as an IBD susceptibility gene showing ethnic-specific associations in a Caucasian population. The protective Haplotype B (OR=0.64, p=0.01 in CD; OR=0.59, p=0.01 in UC) was significantly associated with disease protection in non-Jewish controls but showed opposite frequency trends in Jewish populations (p=0.04 for gene-ethnicity interaction in CD), demonstrating disease susceptibility is ethnically determined.