In addition, homozygous Pkd1Col1a1(3.6)-cKO mice had significantly higher levels of serum BUN, PTH, and FGF23, but lower levels of phosphorus, and no changes in calcium levels at 6 weeks of age (Table 2), consistent with the development of renal impairment caused by polycystic kidney disease and secondary induction of compensatory hormonal changes (Table 2). This evidence concerns the gene PTH and polycystic kidney disease.