The Human Doublesex-Related Gene, DMRT2,Is Homologous to a Gene Involved in Somitogenesis and Encodes a Potential Bicistronic Transcript

Intense efforts are currently being pursued to identify autosomal genes associated with 46,XY male-to-female sex reversal. The genes DMRT1and 2are located on distal 9p, a region deleted in 46,XY sex-reversed patients. They are considered excellent candidates because of their homology to regulators of sex development in invertebrates. We present the genomic structure of DMRT2,showing that it generates several transcripts with distinct coding potential. In addition to the previously reported 226-amino-acid protein-encoding transcript, we describe other mRNA isoforms that are potentially bicistronic and are predicted to encode an additional 328-amino-acid polypeptide. Finally, a stop codon-containing exon (exon 4) can be skipped by alternative splicing and can generate a transcript that is predicted to encode a fusion protein. The latter shares 58% amino acid identity with a gene recently described in fish, termed terra.Differences in expression pattern exist for DMRT2mRNA isoforms among the human adult tissues tested, between adult tissues and human embryos, and between DMRT2and DMRT1during embryonic development. We failed to detect mutations by sequencing of DMRT2in a sample of 46,XY female patients. The interesting structure of DMRT2coupled to preliminary functional studies in fish showing that terrais involved in somitogenesis suggests that validation or exclusion of this gene as a cause of sex reversal will require more in-depth investigations.