monilethrix

noun

mo·​nil·​e·​thrix mə-ˈnil-ə-ˌthriks 

plural moniletriches ˌmän-ə-ˈle-trə-ˌkēz 

: an inherited disease of the hair in which each strand of hair has a beaded appearance due to periodic narrowing of the hair shaft and that is marked chiefly by fragile, brittle hair and patchy alopecia

Note: Monilethrix is typically inherited as an autosomal dominant trait requiring only one parent pass on a copy of the defective gene on a chromosome other than a sex chromosome.