KCNQ1 and hereditary gingival fibromatosis: A second gene in the IC2 region, potassium voltage-gated channel subfamily Q member 1 (KCNQ1), has also been associated with gonadal development, since maternally inherited missense mutations in this locus can cause growth hormone deficiency (GHD) and gingival fibromatosis (OMIM 611010), a condition that presents with gonadotrophin deficiency [27].