ERAP1

Ankylosing spondylitis

Variations (polymorphisms) in the ERAP1 gene have been found to influence the risk of ankylosing spondylitis. This condition is a form of painful, ongoing joint inflammation (chronic inflammatory arthritis) that primarily affects the spine. Each of the ERAP1 gene variants changes a single protein building block (amino acid) in endoplasmic reticulum aminopeptidase 1. Individuals with an ERAP1 polymorphism who go on to develop ankylosing spondylitis tend to also have a variant in the HLA-B gene (specifically, the HLA-B27 variant).

Researchers believe that changes in the  structure of endoplasmic reticulum aminopeptidase 1 could alter either of its two major functions. Other genetic and environmental factors, many of which are unknown, also affect the chance of developing ankylosing spondylitis.