- X-linked mental retardation and autism are associated with a mutation in the NLGN4 gene, a member of the neuroligin family. Laumonnier, F., Bonnet-Brilhault, F., Gomot, M., Blanc, R., David, A., Moizard, M.P., Raynaud, M., Ronce, N., Lemonnier, E., Calvas, P., Laudier, B., Chelly, J., Fryns, J.P., Ropers, H.H., Hamel, B.C., Andres, C., Barthélémy, C., Moraine, C., Briault, S. Am. J. Hum. Genet. (2004)