Many of the genes in which loss-of-function variants are identified in individuals with CHH encode receptor-ligand pairs, for example: GNRH1 (MIM 152760) and its receptor (encoded by GNRHR, MIM 138850); and Kisspeptin-1 (KISS1, MIM 603286) and its receptor KISS1R (MIM 604161). This evidence concerns the gene KISS1R and cartilage-hair hypoplasia.