- Mutations in two nonhomologous genes in a head-to-head configuration cause Ellis-van Creveld syndrome. Ruiz-Perez, V.L., Tompson, S.W., Blair, H.J., Espinoza-Valdez, C., Lapunzina, P., Silva, E.O., Hamel, B., Gibbs, J.L., Young, I.D., Wright, M.J., Goodship, J.A. Am. J. Hum. Genet. (2003)