Browsing by Author "Hillermann, R."

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    Analysis of two mutations in the MTHFR gene associated with mild hyperhomocysteinaemia - heterogeneous distribution in the South African population
    (Health & Medical Publishing Group, 2002-6) Scholtz, C. L.; Odendaal, H. J.; Thiart, R.; Loubser, L.; Hillermann, R.; Delport, R.; Hayward Vermaak, W. J.; Kotze, M. J.
    Objective. The frequencies of mutations 677C→T and 1298A→C in the methylenetetrahydrofolate reductase (MTHFR) gene, previously shown to be associated with decreased enzyme activity that may lead to hyperhomocysteinaemia and consequently increased risk of cardiovascular disease (CVD), were determined in the South African population. Methods. HinfI (677C→T) and MboII (1298A→C) restriction enzyme analyses were performed on amplified DNA samples of 76 white, 73 coloured and 60 black subjects. Results. The mutant alleles of mutations 677C→T and 1298A→C were more common in the white (allele frequencies 0.36 and 0.37, respectively) than in the black population (0.04 and 0.09), while intermediate frequencies were detected in the coloured population (0.18 and 0.30). Homozygosity for mutation 677C→T was not detected in the black cohort, while this genotype was detected in 1 coloured (1.4%) and 8 white (10.5%) subjects. In the black population, 5% of the 60 subjects analysed were homozygous for mutation 1298A→C, compared with approximately 12% in both the white and coloured populations. Conclusions. Since hyperhomocysteinaemia is a risk factor for premature CVD, the heterogeneous distribution of the 677C→T and 1298A→C mutations across ethnic groups may partly explain ethnic differences in heart disease risk through decreased enzyme activity and hence increased homocysteine levels.
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    Mutations in prothrombin and factor V genes do not contribute significantly to placental vasculopathy in a high-risk patient cohort in South Africa
    (Health & Medical Publishing Group, 2002) Hillermann, R.; Gebhardt, G. S.; Isaacs, R.; Steyn, D. W.; Odendaal, H. J.
    During normal pregnancy there are dramatic changes in the coagulation and fibrinolytic systems. There is deposition of fibrin in the uteroplacental walls and fibrinolysis is suppressed. An increase in levels of clotting factors VII, VIII and X and a doubling in the levels of fibrinogen are observed. The end result is the well-described hypercoagulability of pregnancy, protecting the mother against blood loss at delivery, but also predisposing her to possible thrombotic complications. Naturally occurring anticoagulants including antithrombin III and the protein C-thrombomodulin-protein S complex protect against generalised thrombosis. Protein C (with its co-factors protein S and thrombomodulin) inactivates factors V and VIII. Abnormal forms of factor V, such as those arising from DNA mutation, resist such inactivation and thrombosis can result.