Objectives: To assess whether there is excess transmission of alleles from the ERAP1 ERAP2 locus in families with ankylosing spondylitis (AS).
Methods: 199 multiplex families with AS with four non-synonymous single nucleotide polymorphisms (SNPs), three in the endoplasmic reticulum aminopeptidase 1 (ERAP1) gene (rs27044, rs10050860 and rs30187) and one in the endoplasmic reticulum aminopeptidase 2 (ERAP2) gene (rs2549782), were genotyped and family-based association analyses were performed.
Results: Family-based association testing (FBAT -e; empirical variance option) analysis showed 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 locus (rs27044[G] rs30187[T] rs2549782[T]) was significantly associated with AS (two-sided p value by permutation test 0.009 for additive and 0.008 for dominant model, respectively).
Conclusion: This study shows that one ERAP1 SNP and a haplotype in the ERAP1 and ERAP2 locus are associated with familial AS.