Compared to age-matched wild-type (WT) mice, bone DMP1 mRNA expression was significantly reduced by 30%–40% in slow progressing B6 Col4a3−/− mice (Fig. 1a) and fast progressing 129Sv-Col4a3−/− mice (Fig. 1b) with advanced CKD, at 20 weeks and 9 weeks of age, respectively. This evidence concerns the gene COL4A3 and chronic kidney disease.