Alopecia areata (AA) is an inflammatory hair loss disorder with a major genetic component, which may cause great psychosocial distress for those affected. Studies have shown that interleukin-1 (IL-1) is a very potent inducer of hair loss and a significant human hair growth inhibitor. The 4-bp insertion/deletion (Indel) polymorphism (rs3783553) within the 3' untranslated regions of ILIA gene has been suggested to be associated with risk of various types of cancers, possibly through regulating expression of IL-1 alpha levels. In the current study, we estimated the susceptibility to M associated with rs3783553 in two independent case-control panels of Eastern and Southern Chinese populations, totally containing 313 AA cases and 626 healthy controls. Logistic regression analysis showed that the heterozygote and the homozygote 4-bp ins/ins confer a significantly lower risk of AA in both panels and total subjects [odds ratio (OR) = 0.55, 95% confidence interval (Cl.) = 0.41-0.75, P = 6.24 x 10(-5); OR = 0.47, 95% C.I. = 028-0.76, P = 0.001, respectively]. Stratification analysis based on age onset showed that the protective roles of ins/del and ins/ins genotype against developing AA was more obvious in M patients with early age onset (<30 years) under dominant model (OR = 0.48,95% C.I. = 0.29-0.77, P = 0.001). The results of luciferase assay showed that rs3783553 could influence expression of IL-1 alpha in a miR-122 dependant manner. Taken together, our results suggested that the MA 4-bp indel polymorphism may be a marker for genetic susceptibility to patchy (mild) M in Chinese populations, likely through miR-122 mediated regulation. (C) 2013 Elsevier B.V. All rights reserved.