ERAP2 and ankylosing spondylitis: However, high expression of ERAP2 is in general viewed as unfavorable in the context of inflammation, with multiple SNPs in the genomic neighborhood of ERAP2 associated with inflammatory diseases, including IBD (especially Crohn’s Disease), ankylosing spondylitis, birdshot chorioretinopathy, psoriasis, preeclampsia, and hypertension [9–11].