Homocystinuria presenting as multiple arterial occlusions.

We describe a patient with pyridoxine-responsive homocystinuria who presented with multiple arterial occlusions after pregnancy but who showed no other stigmata of the disease and we suggest that in patients with unusual vascular lesions, screening for homocystinuria should be carried out even in the absence of the other manifestations of the condition. Family screening showed that her brother was also affected but that their children were not, confirming the autosomal recessive model of inheritance. We found the index case to have normal platelet behaviour; both she and her brother had normal veins and arteries on biopsy, so the mechanisms underlying the thrombotic complications remain uncertain. It seems likely that pregnancy contributed to the time of onset of the thrombotic complications in the index case, because of the foetal demands for pyridoxine or folate during gestation.