The BRDT gene and its transcripts (bromodomain testis-specific gene, also referred to as FSRG3 or BRD6) represent potential candidates for studying the role of epigenetic changes for fertility and paternal contribution to the embryo, as they play an important role in the establishment of proper germ cell differentiation. The first bromodomain of the BRDT protein recognises the acetylation marks of histone 4 in order to start chromatin remodelling. In addition, male mice carrying a mutation within the allele of the first bromodomain are subfertile. BRDT transcripts have been demonstrated to be specifically expressed in human and murine testis. In the latter, Brdt mRNA has been observed from pachytene spermatocytes to spermatids. In man, a splicing variant of the BRDT gene (BRDT-NY) was found in embryonic and adult human testis and spermatozoa from fertile men. By contrast, transcripts of this splicing variant could not be detected in testis of some azoospermic men including arrest of spermatogenesis at the level of round spermatids. As spermatozoa are known to contain a variety of transcripts and mRNAs could be delivered from sperm to oocyte, it might be possible that BRDT mRNA influences chromatin compaction during spermiogenesis and/or expression of BRDT during early embryogenesis.
