Autosomal dominant (AD) transmission of CHH is seen more often in KS than in nCHH, with the most common genes (causing both nCHH and KS) being FGFR1 and CHD7. FGFR-1 encodes a tyrosine kinase receptor that regulates central developmental processes such as neuronal migration, fate, determination, and cell proliferation (41). This evidence concerns the gene FGFR1 and cartilage-hair hypoplasia.