Browsing by Author "Retief, A. E."
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- ItemA DNA polymorphism in the human low-density lipoprotein receptor gene(Health and Medical Publishing Group -- HMPG, 1986-07) Kotze, M. J.; Retief, A. E.; Brink, P. A.; Weich, H. F. H.A new restriction fragment length polymorphism (RFLP) in the low-density lipoprotein receptor gene is described using the Stu I restriction endonuclease and a cDNA probe. The frequency of the two RFLP alleles was determined in 60 unrelated white subjects and 11,70/6 of them were found to be heterozygous for the polymorphism. Mendelian segregation of the RFLP was found in 3 informative families. The possible use of the RFLP in the diagnosis of familial nypercholesterolaemia in South Africa is discussed.
- ItemThe frequency of the delta F508 mutation in the cystic fibrosis genes of 71 unrelated South African cystic fibrosis patients(Health & Medical Publishing Group, 1992) Herbert, J. S.; Retief, A. E.The common ΔF508 mutation is present in approximately 70% of mutant cystic fibrosis (CF) genes of European and North American populations. The frequency of the ΔF508 mutation has been established for two groups of South African CF subjects. The mutation was found to be present in 82% and 53% of CF genes of white and coloured (i.e. of mixed ancestry) subjects respectively. These findings assist in providing appropriate counselling to individuals who have a family history of CF and in defining laboratory strategies for the establishment of an efficient genetic service for cystic fibrosis.
- ItemMolecular characterisation of a low-frequency mutation in exon 8 of the human low-density lipoprotein receptor gene(Health & Medical Publishing Group, 1989) Kotze, M. J.; Langenhoven, E.; Warnich, Louise; Marx, M. P.; Retief, A. E.The prevalence of familial hypercholesterolaemia (FH), an autosomal dominant disease characterised by raised low-density lipoprotein (LDL) cholesterol levels, is at least five times higher in the white Afrikaner population than in most other population groups in the world. A founder gene effect has been suggested to explain this abnormally high frequency. Detection of a polymorphic Stu I site in the 5' region of the LDL receptor gene and association of both restriction fragment length polymorphism alleles with FH in Afrikaners, indicated the existence of at least two founder members of the disease in this population. DNA from a hetero-allelic FH homozygote from this South African group has been analysed through genomic cloning and sequencing. The DNA polymorphic site is caused by a single guanine to adenine transition within exon 8 of the LDL receptor gene and can be used in the determination of haplotype-associated defects.
- ItemRekenaarhantering van genetiese pasientdata(HMPG, 1979-06) Retief, A. E.A code form for genetic patient data has been devised for computer purposes. This form provides for the clinical and laboratory diagnosis of genetic diseases. A Hewlett-Packard 2100 computer is used for storage and retrieval of the data. Three programmes are currently in use for the retrieval of data, namely programme RETREV, for retrieval of individual patient records; programme STAT9A, for the classification of chromosome results of patients referred with similar clinical diagnoses; and programme STA12A, for classification of chromosome abnormalities and for correlation with the indication for referral and other data. The possibilities for expansion of the programmes are discussed.
- ItemStatus and prospects of genetic disease(Health & Medical Publishing Group, 1978) Retief, A. E.The current status of our knowledge of genetic diseases is reviewed. The incidence of monogenic, multifactorial and chromosomal disorders, according to the literature to date, is given, and the possibilities of mass screening programmes are discussed. The prospects for antenatal diagnosis of genetic diseases are reviewed, with emphasis on the indications for amniocentesis and the safety of the procedure. Finally, speculations are made regarding the possible effects of medical and social practices on the frequency of genetic disorders in future generations.
- ItemThe use of DNA markers in the pre-clinical diagnosis of familial adenomatous polyposis in families in South Africa(Health & Medical Publishing Group, 1995) Grobbelaar, J. J.; Oosthuizen, C. J. J.; Madden, M. V.; Bailey, S. E.; Retief, A. E.; Kotze, M. J.Haplotype association studies were performed in 10 unrelated South African families and 1 German immigrant family with familial adenomatous polyposis (FAP). Three DNA probes, recognising five restriction fragment length polymorphisms (RFLPs) around the gene locus for FAP on chromosome 5q, were used. The RFLP analysis was informative or partially informative in all the families studied. Five haplotypes were found to segregate with the disease locus. The predominant association of two of these haplotypes with FAP in the South African families suggests that two mutations may cause the disease in about 70% of families in this population. Meiotic recombination events were detected between the FAP gene and probe M4 (D5S6), but not probes Pi227 (D5S37) and C11p11 (D5S71). Haplotype analysis allowed the preclinical diagnosis of FAP in 5 subjects.