RBMY genes and AZFb deletions

Microdeletions of the AZFb region of the human Y chromosome usually result in severe consequences for spermatogenesis. AZFb contains at least four kinds of genes/gene families. These include a number of RBMY genes, which are clustered in the AZFb deletion interval. They are amongst the oldest genes on the mammalian Y chromosome, and are related to the gene encoding hnRNPG (RBMX) on the X chromosome. A retroposon-derived version of these genes is found on chromosome 11 that might replace the function of these genes during meiosis, during which time the X and Y chromosomes are transcriptionally inactivated. Each of these genes encodes proteins with an RNA binding motif, and interacts with more ubiquitously expressed proteins involved in pre-mRNA splice site selection. These findings imply that important pre-mRNA processing pathways might be disrupted in the germ cells of AZFb men.