The fact that calcium deposits were not found by Von Kossa staining, a method routinely used on patient skin biopsies for diagnosis of PXE, may be explained by the patchy mineral deposition pattern in the LV of Abcc6−/− DOCA mice, as previously reported in the TA of old Abcc6−/− mice20. The gene discussed is ABCC6; the disease is Pseudoxanthoma elasticum.