- A member of a gene family on Xp22.3, VCX-A, is deleted in patients with X-linked nonspecific mental retardation. Fukami, M., Kirsch, S., Schiller, S., Richter, A., Benes, V., Franco, B., Muroya, K., Rao, E., Merker, S., Niesler, B., Ballabio, A., Ansorge, W., Ogata, T., Rappold, G.A. Am. J. Hum. Genet. (2000)