Abstract: Objective To describe the genetic epidemiologic features of alopecia areata (AA) patients in China and to presume the possible genetic model of AA. Methods A case-controlled study of 1032 AA patients was performed to analyze the effect of genetic factors on the liability to AA.Complex segregation and heritability analysis were performed using Falconer's method and SAGE-REGTL programs. Results The meanage of onset was 28.98±13.43 years.The difference in the meanage of onset was not significant between males and females.A total of 82.6 percent of patients experienced their first episode of AA before the fourth decades of life.A positive family history of AA was obtained in 8 7 patients (8.43%).The prevalences of AA were 1.58%,0.19% and 0.03% in the first-,second-and third-degree relatives of the probands respectively,which were significantly higher than those in the controls(P<0.001=.The heritabili ties of AA were 47.16%±2.79%,42.53%±7.36% and 22.29%±21.63% in the first-,second-and third-degree relatives,respectively,the weighted mean heritability was 46.23%±0.07%.Based on the REGTL results,the best model was a polyge nicadditive model for AA. Conclusion It can be concluded that AA is a polygenic disease.Genetic factors play an important role in the pathogenesis of AA.

Key words: Alopecia areata, Genetic epidemiology