Browsing by Author "Scholtz, Charlotte L."

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    Analysis of two mutations in the MTHFR gene associated with mild hyperhomocysteinaemia - heterogeneous distribution in the South African population
    (Health and Medical Publishing Group (HMPG), 2002-06) Scholtz, Charlotte L.; Odendaal, Hein J.; Thiart, Rochelle; Loubser, Lynzie; Hillermann, Renate; Delport, Rhena; Hayward Vermaak, W. J.; Kotze, Maritha 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 ill 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 8white (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.
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    Lipoprotein(a) determination and risk of cardiovascular disease in South African patients with familial hypercholesterolaemia
    (Health & Medical Publishing Group, 2000) Scholtz, Charlotte L.; Lingenhel, Arno; Hillermann, Renate; Stander, Ilse A.; Kriek, Josef A.; Marais, Martelle P.; Odendaal, Hein J.; Kraft, Hans G.; Utermann, Gerd; Kotze, Maritha J.
    Objective. A raised plasma level of lipoprotein(a) (Lp(a)) is an established genetic risk factor for coronary heart disease (CHD), particularly in patients with concomitant elevation of low-density lipoprotein (LDL) cholesterol. The current study focused on the comparison of two commercially available Lp(a) assay kits to determine whether differences observed in measured Lp(a) levels could be deemed negligible in CHD risk assessment in familial hypercholesterolaemic (FH) patients. Design. To compare results obtained on duplicate plasma samples using two commercially available Lp(a) measuring kits, the immunoradiometric assay (RIA) and the enzyme-linked immunoabsorbent assay (ELISA). Setting. Division of Human Genetics, Department of Obstetrics and Gynaecology, University of Stellenbosch, Tygerberg, South Africa and the Institute for Medical Biology and Human Genetics, University of Innsbruck, Austria. Subjects. Plasma samples were obtained from 146 family members of 65 molecularly characterised South African FH families for comparative analysis. Results. Using the RIA method, 34 samples (23%) considered to be in the normal range by the ELISA technique, were placed in the high-risk group (> 30 mg/dl). Only one sample, considered to have a normal Lp(a) level with the RIA method, was categorised by the ELISA technique as high risk. Conclusion. Our data demonstrate that measurements of Lp(a) using the RIA method (the only assay available in South Africa at the time of this study) differ significantly from those obtained by the reference ELISA technique, suggesting that misclassification could lead to inaccurate CHD risk assessment. This is an important consideration in Afrikaner FH families, where plasma levels of Lp(a) have been shown to be elevated significantly in FH patients compared with non-FH individuals.