Plasma homocysteine levels, methylene tetrahydrofolate reductase polymorphisms, and the risk of thromboembolism in children

Introduction: Hyperhomocystenemia (HHcy) is a risk factor for thrombosis in adults. Polymorphisms in methylene tetrahydrofolate reductase (MTHFR) enzyme may cause HHcy. Data on their role in pediatric thromboembolism (TE) are sparse. MATERIALS AND Methods: Charts of patients from 1989 to 2007, with documented TE, were reviewed. Homocysteine (Hcy) levels were defined both as per the adult normal range and the age-specific normal ranges from literature. Results: A total of 141 patients (67 females, 74 males) were identified. With age-specific normal ranges for Hcy, 15 patients were found to have HHcy: 6 had CT, 9 patients had CC, and none had TT MTHFR genotype. When adult normal range was used, HHcy (>12 μmol/L) was seen in 7 patients: 4 had CT and 3 had the CC genotype. Again, none had TT genotype. In addition, the mean Hcy levels were unaffected by sex and ethnicities, but universal folic acid supplementation (post 1996) lowered the mean. Conclusions: (1) Age-specific ranges for Hcy should be used in pediatrics for accurate diagnosis of HHcy. (2) MTHFR C677T polymorphism is not a risk factor in pediatric TE. (3) Folic acid supplementation could play a role in lowering the prevalence of HHcy.