VCX/Y Background Information
Human chromosome X contains nearly 153 million base pairs and houses over 1,000 genes, while human chromosome Y contains approximately 58 million base pairs and houses over 80 genes. The VCX and VCY (variable charge, X-linked and Y-linked, respectively) gene families are found on X and Y chromosomes and encode small, highly charged proteins that are expressed specifically on male germ cells and may be involved in spermatogenesis. There are six members of the VCX/Y family, namely VCX-A, VCX-B, VCX-B1, VCX-C, VCY and VCY1B, all of which share a high degree of homology, with the exception of an amino acid sequence that is tandemly repeated in VCX proteins, but occurs only once in VCY proteins. Mutations or deletions in the genes encoding VCX proteins are associated with X-linked mental retardation.
