Browsing by Author "Retief, A. E."

Now showing 1 - 11 of 11
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    Balanced chromosome translocations and abnormal phenotypes. A report of 5 cases
    (Health & Medical Publishing Group, 1986-6) Van Heerden, K. M. M.; De Jong, G.; Fox, M. F.; Kotze, G. M.; Brusnicky, J.; Dietzsch, E.; Grobbelaar, J. J.; Retief, A. E.
    ENGLISH ABSTRACT: Five cases in which phenotypic abnormalities were found in association with apparent balanced chromosomal translocations are described. In 3 patients, one of the parents was found to be carrier of the same translocation. In a further patient, the translocation was shown to be de novo and in the remaining patient the father was not available for chromosome studies. In a review of the literature the breakpoints in 36 familial balanced translocations were compared with 40 de novo translocations (including the present cases) all associated with phenotypic abnormalities. No common translocation was found in these groups, but it was observed that chromosomes 4 and 5 were significantly more involved in de novo translocations than in familial translocations. The possible aetiology and implications for prenatal diagnosis are discussed.
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    Chromosoomstudies in die ginekologie
    (1985-10) Retief, A. E.
    Clinical indications for chromosome analysis in patients with gynaecological problems are well defined. These include, with primary or secondary amenorrhoea, infertility and repeated miscarriages in adults or retarded puberty and abnormal sexual development in young girls. The type of chromosome abnormality, the incidence, and the management of patients are discussed with reference to 15 years' experience in the Department of Gytogenetics at Tygerberg Hospital. The cytogenetics of 419 patients with amenorrhoea are discussed under headings such as gonadal dysgenesis, monosomy X, chromosome mosaics and the XY female phenotype. Results of chromosome studies in 540 males with a low sperm count are given. The importance of chromosome studies in repeated miscarriages and genetic counselling for carriers of balanced translocations is stressed.
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    Clinical and cytogenetic aspects of the 21 deletion syndrome
    (Health and Medical Publishing Group (HMPG), 1975) Gericke, G. S.; Steyn, M. F.; Retief, A. E.; Thom, J. C.; Van Niekerk, W. A.
    The clinical, cytogenetic and dermatoglyphic findings in a patient with a ring chromosome 21 are presented. This anomaly acts as a deletion of chromosomal material and results in specific congenital defects. A comparison is made with 24 cases of deletions involving chromosome 21 described in the literature. Six of these have been studied by means of recently developed chromosome banding techniques. Cases presumably arise through somatic non disjunction or chromosome breakage. When the chromosomes of both parents are normal the recurrence risk is negligible.
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    A 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.
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    The 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.
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    The identification of two low-density lipoprotein receptor gene mutations in South African familial hypercholesterolaemia
    (Health & Medical Publishing Group, 1989) Kotze, M. J.; Langenhoven, E.; Warnich, Louise; Du Plessis, L.; Marx, M. P.; Oosthuizen, C. J. J.; Retief, A. E.
    Two point mutations were discovered in the low-density lipoprotein genes of patients with familial hypercholesterolaemia (FH). Defective genes were cloned and/or amplified by the polymerase chain reaction (PCR) method and the DNA sequences determined. A guanine to adenine base transition in exon 4 was found to be the molecular defect in 20% of cases of FH in the Afrikaner population. A second mutation, a guanine to adenine base substitution in exon 9, was identified in two homozygous FH individuals. Restriction enzyme analysis of PCR-amplified DNA from blood and tissue samples now permits accurate diagnosis of these mutations.
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    Molecular 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.
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    Probleme met betrekking tot genetiese voorligting vir arthrogryposis multiplex congenita
    (Health and Medical Publishing Group (HMPG), 1975) Gericke, G. S.; Retief, A. E.; Van Niekerk, W. A.
    Arthrogryposis multiplex congenita (AMC) is a rare condition, which presents various problems to the genetic counsellor. Two cases are described and the possible modes of inheritance are discussed. A review of the literature in this respect favours an autosomal recessive inheritance which is, however, not applicable to all cases.
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    Rekenaarhantering 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.
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    Status 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.
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    The 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.