Another important aspect is the possible reversal of hypogonadism, to date described in patients carrying variations in nine genes (KAL1, FGFR1, CHD7, HS6ST1, PROKR2, NSMF, GNRHR, TAC3 and TACR3) (11), that complicates the differential diagnosis between CHH and self-limited DP in cases with a mild normosmic phenotype. The gene discussed is HS6ST1; the disease is cartilage-hair hypoplasia.