Objectives: We assessed whether there is excess transmission of alleles from the ERAP1 ERAP2 locus in ankylosing spondylitis (AS) families.
Methods: We genotyped 199 multiplex AS families with four non-synonymous SNPs: three in the ERAP1 gene (endoplasmic reticulum aminopeptidase 1; rs27044, rs10050860 and rs30187) and one in the ERAP2 gene (endoplasmic reticulum aminopeptidase 2; rs2549782) and performed family-based association analyses.
Results: Family-Based Association Testing (FBAT –e; empirical variance option) analysis revealed that ERAP1 rs30187[T] was associated with AS (additive model: P = 0.02; dominant model: P = 0.007). Haplotype permutation tests (HBAT -p) showed that a haplotype in the ERAP1 and ERAP2 loci (rs27044[G] rs30187[T] rs2549782[T]) was significantly associated with AS (2-sided P value by permutation test: 0.009 for additive and 0.008 for dominant model respectively).
Conclusion: We showed that one ERAP1 SNP and a haplotype in the ERAP1 and ERAP2 locus are associated with familial AS.