The FSH/LH ratios in these 11 patients were compared, using the same assays (see below), with those in patients with CHH of different genetic origins, namely 4 patients with biallelic mutations in KISS1R, 11 with biallelic mutations in GNRHR, 32 nCHH patients with no identified mutations in genes known to cause nCHH and also with those of 50 patients with Kallmann syndrome and mutations in KAL1 (n = 19) or FGFR1 (n = 17), or PROK2/PROKR2 (n = 14) (Information S1). The gene discussed is PROK2; the disease is Kallmann syndrome.