A Revised Genome Assembly of the Region 5' to Canine SOX9 Includes the RevSex Orthologous Region.

The SOX gene family includes many genes that play a determinant role in several developmental pathways. The SOX9 gene has been identified as a major factor in testis development in mammals after it is activated by the SRY gene. However, duplication of the gene itself in some mammalian species, or of a well-delimited upstream 'RevSex' region in humans, has been shown to result in testis development in the absence of the SRY gene. In the current study, we present an accurate analysis of the genomic organization of the SOX9 locus in dogs by both in silico and FISH approaches. Contrary to what is observed in the current dog genome assembly, we found that the genomic organization is quite similar to that reported in humans and other mammalian species, including the position of the RevSex region in respect to SOX9. The analysis of the conserved sequences within this region in 7 mammalian species facilitated the highlighting of a consensus sequence for SRY binding. This new information could help in the identification of evolutionarily conserved elements relevant for SOX9 gene regulation, and could provide valid targets for mutation analysis in XY DSD patients.