Prevalence of the prothrombin 20210 G-to-A variant in blacks: Infants, patients with venous thrombosis, patients with myocardial infarction, and control subjects

A genetic variation in the prothrombin gene is located in the 3'-untranslat ed region at position 20210 where a G-->A transition occurs, The prevalence of the mutation is 1% to 2% in white populations, and the mutation is asso ciated with an increased risk of venous thrombosis and myocardial infarctio n. We report the prevalence of the A allele in blacks at birth; in black co ntrol subjects with no history of heart attack, stroke, or blood clots; in black patients with venous thrombosis; and in black patients with myocardia l infarction. Among 318 infants, the prevalence of the A allele was 0.2% (1 heterozygote), with an exact, one-sided upper 95% confidence limit of 0.7% . Among 185 control subjects the variant was absent, yielding an exact, one -sided upper 95% confidence limit of 0.8% for the A allele, The heterozygou s genotype was found in 2 of 91 subjects with deep vein thrombosis and in n one of 123 subjects with myocardial infarction. The very low prevalence of the A allele indicates that the prothrombin variant is not a major cause of venous thrombosis or myocardial infarction in blacks.