A Tall and Thin Boy with a Bad Headache: A Case Report of Homocystinuria

Abstract Background: Homocystinuria is a rare inborn error of metabolism, resulting in the accumulation of homocysteine and methionine in tissues, which manifests as disorders of the connective tissues and increased risk of thromboembolism. The latter is the primary cause of morbidity and mortality, and can be prevented by the prompt start of the specific therapy aimed at lowering homocysteine plasma levels.Case presentation: A nine-year-old boy was admitted to the Emergency Department for a severe headache associated with torticollis, dysarthria, difficulty in walking and extreme irritability. His past medical history was relevant for bilateral lens ectopia and epilepsy, associated with a “marfanoid habitus”. A brain CT scan was consistent with cerebral venous thrombosis. The association between the marfanoid habitus and the thromboembolic event raised the suspicion of homocystinuria, which was eventually confirmed by the high levels of serum homocysteine, and the genetic testing. Anticoagulation therapy was started, together with pyridoxine and folate, and eventually betaine and dietary protein restriction, with a consequent satisfactory fall in homocysteine levels, along with clinical recovery.Conclusions: This case enhances the importance of dosing serum homocysteine in every child investigated for a marfanoid habitus, given the impact of the early diagnosis and treatment in the prevention of thromboembolic events.