RESUMO
Leukodystrophies and genetic leukoencephalopathies comprise a diverse group of neurodegenerative disorders of white matter with a wide age of onset and phenotypic spectrum. Patients with white matter abnormalities detected on magnetic resonance imaging (MRI) often present a diagnostic challenge to both general and specialist neurologists. Patients typically present with a progressive syndrome including various combinations of cognitive impairment, movement disorders, ataxia, and upper motor neuron signs. There are a number of important and treatable acquired causes for this imaging and clinical presentation; one of the causes is hyperhomocystinemia due to 5,10-methylenetetrahydrofolate reductase (MTHFR) deficiency. MTHFR deficiency is a genetic disorder that can occur at any age and can be easily detected by increased serum homocysteine levels and it is a treatable cause. Metabolic therapies like betaine were shown to be effective in children and adults to stop the disease progression and sometimes improve neurologic disabilities. Herein, we report a 16-year-old male with gradually progressive spastic paraparesis with history of cerebral venous sinus thrombosis and poor scholastic performance. The patient was diagnosed with MTHFR enzyme deficiency presenting as leukodystrophy with spastic paraparesis, which is treatable on early diagnosis. Treatment with betaine produced a rapid decline of homocysteine and improved the condition.