Rate of change of carotid intima-media thickness with magnesium administration in Abcc6⁻/⁻ mice.

Pseudoxanthoma elasticum (PXE), caused by mutations in the ABCC6 gene, demonstrates progressive build-up of calcium phosphate and proteoglycans in the skin, eye, and arteries, and is associated to myocardial infarctions, stroke, blindness, and elevated carotid intima-media thickness (CIMT). Although CIMT reduction with magnesium (Mg) has been documented in a mouse model for PXE (Abcc6(-/-) ), it is not clear if Mg is effective in humans with PXE to reduce CIMT. To examine this, we calculated the rate of change of CIMT (washout) in 15- and 12-month-old Abcc6(-/-) mice fed standard rodent diet with or without Mg supplementation for 2 months. Using means in untreated 15- and 12-month-old Abcc6(-/-) mice (145 and 120 μm, respectively), the rate of change was 8.3 μm/month. Using means in treated 15- and 12-month-old Abcc6(-/-) mice (118 and 104.6 μm, respectively), the rate of change was 4.5 μm. Compared to normal progression of CIMT in humans without PXE, PXE has advanced atherosclerosis and possibly a higher CIMT rate of change. This experiment may portend, at least in PXE, the rationale for a 1-year oral Mg CIMT clinical trial and may be useful for application in other progressive mineralizing disorders like atherosclerosis.