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The SPANX gene family encompasses a group of genes involved in spermatogenesis. The SPANX-N subfamily genes are present in one copy in ancestral mammalian species and in greater copies in primates, while the SPANX-A/D subfamily genes are specific to hominoids. SPANX-B and SPANX-C have both undergone human lineage specific changes; SPANX-B has amplified from 1 to 14 copies, and SPANX-C experienced a duplication event.
Evolutionary diversification of SPANX-N sperm protein gene structure and expression., , PLoS One, 2007, Volume 2, Issue 4, p.e359, (2007)
The SPANX gene family of cancer/testis-specific antigens: rapid evolution and amplification in African great apes and hominids., , Proc Natl Acad Sci U S A, 2004 Mar 2, Volume 101, Issue 9, p.3077-82, (2004)