Introduction: Movement disorders associated with homocystinuria have been reported as rare cases. Their physiopathology has not yet been clarified.
Methods: Three siblings in the same family have been described, all with homocystinuria but possessing phenotypic differences.
Result: The first case presented oromandibular dyskinesia, spasmodic dysphonia, tremor, bradykinesia, and generalized dystonia along with the classic findings of homocystinuria. The second case had marfanoid features and ophthalmic complications of homocystinuria, and also evidence of mild rigidity of which the patient did not complain. The third case had only marfanoid features. The most severely affected family member was the first case who also had increased thyroid peroxidase antibodies, antithyroglobulin antibodies, and thyroiditis.
Conclusion: The most severely affected sibling presented movement disorders and evidence of autoimmune thyroiditis. These findings have led us to think that research on the relations between movement disorders, basal ganglia, immunity, autoimmune thyroid diseases, and homocysteine should be continued.