FGF8 and hypogonadotropic hypogonadism: To date, 21 genes associated with KS/nIHH have been identified, namely, KAL1, FGFR1, FGF8, PROKR2, PROK2, CHD7, FGF8, GNRHR, KISS1R, NELF, TAC, TAC3R, GNRH1, KISS1, WDR11, HS6ST1, SEMA3A, SPRY4, IL17RD, DUSP6, FGF17, and FLRT3.