RESUMEN
BACKGROUND: Alopecia areata (AA) is a multifactorial disease characterized by hair loss especially from the scalp. As for other autoimmune conditions, the major histocompatibility complex (HLA) region is associated with AA susceptibility. OBJECTIVE: To provide evidence for the association of specific HLA-DQB1 and HLA-DRB1 alleles with AA in an Italian population, using a case-control approach. METHODS: We performed a case-control study to investigate whether HLA-DQB1 and -DRB1 alleles predispose to AA in the Italian population. HLA class II typing was performed in 85 patients with AA and 210 healthy controls from the same ethnic group. RESULTS: An increased frequency of DQB1*03, coding for DQ7 heterodimers, and a decreased rate of the DQB1*06 allele were observed in patients when compared with controls; the greatest and significant difference was in the group of cases with a more severe phenotype [AA>50% patients (more than 50% hair loss) vs. controls, P=4·5×10(-3) , P(c)=0·031, odds ratio (OR) 2·01, 95% confidence interval (CI) 1·22-3·31 and P=2·5×10(-3) , P(c)=0·017, OR 0·22, 95% CI 0·07-0·72, respectively]. DQB1*03, serologically related to DQ8 or coding for DQ9 molecules, was not associated with AA susceptibility. Out of all patients, 65·9% carried DQ7 heterodimers compared with 49·5% of the controls (P=7·3×10(-3) , OR 1·97, 95% CI 1·17-3·32) and DQ7 prevalence rose to 76·3% in patients with AA>50% (P=1·7×10(-3) , OR 3·28, 95% CI 1·48-7·27). No significant difference was found in the distribution of DRB1 variants or phenotypes among cases and controls. CONCLUSION: Our data show a correlation between the HLA-DQB1 locus and the occurrence of AA in Italy supporting DQB1*03(DQ7) as a predisposing allele for the disease and the relevance of the HLA genetic test in the clinical management of AA.