Thus, genes such as ANOS1 (MIM 300836) [33, 34], CHD7 (MIM 608892) [7, 35], FGFR1 (MIM 136350) [36, 37], PROKR2 (MIM 607123) [38, 39], GNRHR (MIM 138850) [38, 40], TACR3 (MIM 162332) [41, 42] – indeed the majority of these 14 genes – have been repeatedly validated in international cohorts of patients with CHH and KS, with associated in vitro and animal model functional evidence of the molecular mechanisms by which they contribute to the disease and pathogenicity of disease variants [18, 21, 23, 43, 44]. This evidence concerns the gene CHD7 and cartilage-hair hypoplasia.