Consistent with the oligogenic basis of CHH, we identified 7 JAG1 variants, which segregated with mutations in genes previously reported in patients with CHH/KS: SEMA3A, SEMA3E, SEMA7A, IL17DR, PROKR2, or FGFR1 (66–68). This evidence concerns the gene PROKR2 and cartilage-hair hypoplasia.