Half of SIOD individuals develop clinical signs of atherosclerosis. The onset is often in early childhood and relentlessly progressive. The disease is not abrogated by renal or bone marrow transplantation nor by cholesterol lowering agents, although the cholesterol lowering agents and renal transplantation can slow the progression by mitigating factors such as high blood pressure and high blood lipid and cholesterol levels. Consistent with the atherosclerosis resulting from an intrinsic defect of SIOD tissue, the vascular disease does not recur in the transplanted kidneys. Besides atherosclerosis, splitting and fraying of the arterial internal elastic layer and thickening of the muscular layer of the arterial walls have been found on autopsy. The latter finding may be a complication of high blood pressure or an intrinsic defect in the blood vessels. A few patients have also developed subaortic stenosis, one patient showed severe bicuspid aortic stenosis and one patient had extensive fatty infiltration resembling that of arrhythmogenic right ventricular cardiomyopathy.
-National Organization for Rare Disorders