However, we observed a more severe osteopenia in adult Pkd1Col1a1(3.6)-cKO compared to Oc-Cre or Dmp1-Cre-mediated Pkd1 deletion, which could result from the effects of Col1a1(3.6)-Cre to delete Pkd1 during embryogenesis or to the leakiness of this promoter leading to alterations in systemic factors that lead to secondary effects on bone. The gene discussed is PKD1; the disease is Osteopenia.