Three types of polymorphism have been studied in this region to date: a) copy number variation (CNV) in a region about 400 kb upstream of SOX9, named CNVR1; b) duplication of SOX9; and c) insertion of a single G-nucleotide (rs852549625) approximately 2.2 Mb upstream of SOX9. The aim of this study was thus to comprehensively analyze these polymorphisms in a large multibreed case-control cohort containing 45 XX DSD dogs, representing 23 breeds. This evidence concerns the gene SOX9 and disorder of sexual differentiation.