Interleukin-1 receptor antagonist allele 2 and familial alopecia areata

Alopecia areata affects 1%-2% of the population and is hypothesized to be an autoimmune, organ specific T-cell mediated reaction directed against the human hair follicle. It is characterized by loss of hair in patches (alopecia areata) with progression in some individuals to total loss of scalp hair (alopecia totalis) or to loss of all scalp and body hair (alopecia universalis). The interleukin-1 receptor antagonist (IL-1RN) gene was found to be associated with more severe clinical outcome in several chronic inflammatory diseases, including alopecia areata. The IL-1RN*2 allele was found to be associated with alopecia areata severity in a British case-control study. In this paper, we analyzed alopecia areata probands in a family-based sample (n = 131 parent-offspring trios) to study the association between alleles of the IL-1RN and various phenotypes of alopecia areata. In considering all patients with any form of alopecia areata, no association was found with IL-1RN. IL-1RN*2 allele was not associated with alopecia totalis and alopecia universalis. A borderline association was observed between IL-1RN and patchy alopecia areata but it was not statistically significant (p = 0.06). We also observed an association between IL1-RN*1 allele and patchy alopecia areata (p = 0.045).