Is heritability of alopecia areata sex‐specific? A nationwide population‐based cohort study

Previous studies have demonstrated the heritability of alopecia areata (AA). However, whether the heritability of AA is sex-specific has not been examined. A nationwide population-based retrospective cohort study was performed using the Taiwan Maternal and Child Health Database from 2004 to 2017. We examined the heritability of AA in 2,625,440 offspring of parents with and without AA, and determined whether the transmission of AA from parents to the next generation may occur in opposite directions depending on sex. We found that the risk ratio (RR) for heritability of AA between parents with and without AA was approximately two-fold. In addition, for fathers with AA, the risk of AA in offspring tended to be higher in girls than in boys (RR: 2.97; 95% confidence interval: 0.94, 9.31). Therefore, the present study confirms the heritability of AA, and further studies examining the sex-specific heritability of AA with a larger sample are warranted.