To date, various SRA1 gene variants, p.Pro20Leu, p.Tyr35Asn, p.Arg126His and p.Ile179Thr, have been identified in homozygosity, compound heterozygosity, heterozygosity or as digenically inherited with PNPLA6, RNF216 and SEMA7A gene variants in patients with CHH [38,46,47]. The gene discussed is SRA1; the disease is cartilage-hair hypoplasia.