Hyperhomocysteinaemia in a young woman presenting with stroke, associated with methylene tetrahydrofolate reductase C677T homozygosity.

We present a case of ischaemic stroke in a 23-year-old woman, associated with homozygous methylene tetrahydrofolate reductase (MTHFR)-C677T and hyperhomocysteinaemia. Her other risk factors for stroke were ostium secundum atrial septal defect and use of oral contraceptives. This case illustrates the need to include plasma homocysteine (Hcy) measurement in investigations following stroke. In the presence of hyperhomocysteinaemia, the MTHFR genotype should be determined. If the index case has the polymorphism, then all first-degree relatives should also be investigated by measurement of plasma Hcy and determination of MTHFR genotype.