Background

CDY is a gene family expressed exclusively in the testis that localizes to a region of the Y chromosome frequently deleted in infertile males. CDY proteins contain two functional domains, an N-terminal chromodomain, possibly functioning in heterochromatin interactions, and a C-terminal domain, which resembles enoyl-CoA-isomerase, a protein involved in fatty acid oxidation. Furthermore, CDY proteins act as histone acetyltransferases with strong preference for Histone H4, a process required for the histone to proamine transition in spermatogenesis, consistent with the association with male infertility. Chromodomain Y-like protein 2 (CDYL2) is a related nuclear protein that is ubiquitously expressed with moderate levels in most tissues. The gene encoding CDYL2 is located on chromosome 16.