Pseudogenization of testis-specific Lfg5 predates human/Neanderthal divergence.

Recent reviews discussed the critical roles of apoptosis in human spermatogenesis and infertility. These reviews highlight the FasL-induced caspase cascade in apoptosis lending importance to our discovery of the pseudogene status of the Lfg5 gene in modern humans, Neanderthal and the Denisovan. This gene is a member of the ancient and highly conserved apoptosis Lifeguard family. This pseudogenization is the result of a premature stop codon at the 3'-end of exon 8 not found in any other ortholog. With the current exception of the domesticated bovine and buffalo, Lfg5's expression in mammals is testis-specific. A full analysis of this gene, its phylogenetic context and its recent hominin changes suggest its inactivation was likely under selection in human evolution.