- Mutations in fibroblast growth-factor receptor 3 in sporadic cases of achondroplasia occur exclusively on the paternally derived chromosome. Wilkin, D.J., Szabo, J.K., Cameron, R., Henderson, S., Bellus, G.A., Mack, M.L., Kaitila, I., Loughlin, J., Munnich, A., Sykes, B., Bonaventure, J., Francomano, C.A. Am. J. Hum. Genet. (1998)