Genome-wide association studies (GWAS) in Crohn’s disease (CD) have identified associations with single-nucleotide polymorphism (SNP) rs11175593 at chromosome 12q12. The MUC19 and LRRK2 genes reside close to the GWAS signal, but it is as yet unclear which of the 2 genes represent the CD susceptibility genes.
We studied associations between nonsynonymous coding variants in the MUC19 (5) and LRRK2 (3) genes in a case–control sample comprising CD cases aged <18 years at diagnosis. The GWAS lead SNP rs11175593 was also investigated. Allelic, genotype, and haplotype associations were examined assuming different models of inheritance.
A total of 530 cases and 600 controls were studied. The mean (±SD) age at diagnosis was 12.4 (±3.3). Most cases were male (57.4%). Most patients had ileocolonic disease location (48.8%) and inflammatory behavior at diagnosis (87.0%). Three MUC19 SNPs were nominally significantly associated with CD (rs11564245, Asp→His: P = 0.02; rs4768261, Ser→Phe: P = 0.0008; and rs2933353, Glu→Ala: P = 0.01). Associations with rs4768261 were maintained after corrections for multiple comparisons (permuted, P = 0.007). None of the LRRK2 SNPs were associated with CD. Haplotype analysis supported the single SNP associations noted with the MUC19 gene.
GWAS signal at chromosome 12q12 for CD may represent associations with the MUC19 gene.