ANOS1 and Kallmann syndrome: They suggested that the gonadotropin-releasing hormone receptor GNRHR gene (apart from KAL1 and FGFR1) could also be related to Kallmann syndrome, but in their opinion mutations in the GNRHR, KAL1, and FGFR1 genes account for only 15–20% of all possible reasons of idiopathic hypogonadotropic hypogonadism and Kallmann syndrome (GNRHR is a protein that is encoded by the GNRHR gene, which encodes the receptor for type 1 gonadotropin-releasing hormone).