Mutations in FGF10, FGFR2, or FGFR3 have been identified in LADD (lacrimo-auriculo-dento-digital) patients.124,310 Rare FGF10 mutations have been identified in lethal pulmonary hypoplasia.311 Defects in the formation of tracheal cartilaginous ring resulting in mortality, resulting from respiratory distress, have been reported in Crouzon, AS, and PS caused by activating mutations of FGFR2. 312–314 Homozygous loss-of-function mutation (R255Q) of FGFR2 contributes to ectrodactyly and pulmonary acinar dysplasia.315 All these findings suggest the crucial roles of FGF signaling in lung diseases. The gene discussed is FGF10; the disease is LADD syndrome.