When a defective sense of smell, hyposmia or anosmia, is associated with hypogonadotropic hypogonadism, in 60% of patients [13], the disease is called Kallmann syndrome (KS), explained by the common embryonic origins and developmental pathways of GnRH and olfactory neurons [1, 11, 12, 14]. Here, GNRH1 is linked to hypogonadotropic hypogonadism.