Interestingly however, defects reminiscent of polycystic kidney disease (PKD) were also observed, yet exclusively in mutant mice carrying a deletion of more anterior Hoxd genes like Hoxd9 and Hoxd8. Finally, the distinct functions of Hoxd genes in kidneys correlate well with their specific expression in the MM or UB, respectively. This evidence concerns the gene HOXD9 and polycystic kidney disease.