The majority of these patients were compound heterozygous for the classic ACH mutation (p.G380R) and the p.N540K mutation associated with hypochondroplasia (HCH), and they showed a milder skeletal phenotype than homozygous ACH (Chitayat et al., 1999; Flynn & Pauli, 2003; Huggins et al., 1999; Prinos, Costa, Sommer, Kilpatrick, & Tsipouras, 1995; Sommer, Young‐Wee, & Frye, 1987). Here, FGFR3 is linked to hypochondroplasia.