Severe hyperhomocysteinemia manifesting as moyamoya vasculopathy and Henoch-Schonlein purpura

Cystathionine β-synthase (CBS) deficiency is an autosomal recessive disorder affecting homocysteine metabolism resulting in hyperhomocysteinemia and homocysteinuria. A well-known complication of CBS deficiency is premature atherosclerosis and thromboembolic events.1 Specifically, it is associated with an increased risk of early ischemic stroke and myocardial infarction.