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Biomedical subjects

D Viljoen

Publications and source records attributed to D Viljoen.

At least 19 recordsLinked to original sources
PubMed2002

A stereo-photogrammetric method to measure the facial dysmorphology of children in the diagnosis of fetal alcohol syndrome.

In diagnosing a child with fetal alcohol syndrome (FAS), anthropometric measurements of the face are conventionally performed by highly trained dysmorphologists using a hand-held ruler. This renders the screening of large populations of children for the facial features characteristic of FAS very time-consuming and costly. This study proposes a new, cost-effective, and non-intrusive method to measure in three dimensions the facial dysmorphology of children using stereo-photogrammetry. The face of each child is photographed in a control frame simultaneously by a pair of high-resolution digital cameras mounted 1.04 m from the child and 0.26 m apart. Software has been developed to calibrate the images and to compute the three-dimensional object-space coordinates of any point on the face from a measurement of the point on each of the images. The palpebral fissure lengths, inner canthal-, and interpupillary distances of 44 subjects were measured in this manner independently by two investigators and compared with measurements obtained by clinical specialists in the conventional manner. There was found to be no statistically significant difference between palpebral fissure lengths determined using the two techniques (paired Student's t-test p-values are 0.29 and 0.18, respectively). It has also been demonstrated that facial measurements can be performed with greater consistency from a pair of stereo photographs than direct measurements from live subjects.

Anthropometry↗
PubMed2002

Sorting nexin 3 (SNX3) is disrupted in a patient with a translocation t(6;13)(q21;q12) and microcephaly, microphthalmia, ectrodactyly, prognathism (MMEP) phenotype.

A patient with microcephaly, microphthalmia, ectrodactyly, and prognathism (MMEP) and mental retardation was previously reported to carry a de novo reciprocal t(6;13)(q21;q12) translocation. In an attempt to identify the presumed causative gene, we mapped the translocation breakpoints using fluorescence in situ hybridisation (FISH). Two overlapping genomic clones crossed the breakpoint on the der(6) chromosome, locating the breakpoint region between D6S1594 and D6S1250. Southern blot analysis allowed us to determine that the sorting nexin 3 gene (SNX3) was disrupted. Using Inverse PCR, we were able to amplify and sequence the der(6) breakpoint region, which exhibited homology to a BAC clone that contained marker D13S250. This clone allowed us to amplify and sequence the der(13) breakpoint region and to determine that no additional rearrangement was present at either breakpoint, nor was another gene disrupted on chromosome 13. Therefore, the translocation was balanced and SNX3 is probably the candidate gene for MMEP in the patient. However, mutation screening by dHPLC and Southern blot analysis of another sporadic case with MMEP failed to detect any point mutations or deletions in the SNX3 coding sequence. Considering the possibility of positional effect, another candidate gene in the vicinity of the der(6) chromosome breakpoint may be responsible for MMEP in the original patient or, just as likely, the MMEP phenotype in the two patients results from genetic heterogeneity.

Abnormalities, Multiple↗
PubMed2001

Functional relevance of human adh polymorphism.

This article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The chairs were C. J. Peter Eriksson and Tatsushige Fukunaga. The presentations were (1) 4-Methylpyrazole as a tool in the investigation of the role of ADH in the actions of alcohol in humans, by Taisto Sarkola and C. J. Peter Eriksson; (2) ADH2 polymorphism and flushing in Asian populations, by Wei J. Chen, C. C. Chen, J. M. Ju, and Andrew T. A. Cheng; (3) Role of ADH3 genotypes in the acute effects of alcohol in a Finnish population, by Hidetaka Yamamoto, Kathrin Kohlenberg-Müller, and C. J. Peter Eriksson; (4) Clinical characteristics and disease course of alcoholics with different ADH2 genotypes, by Mitsuru Kimura, Masanobu Murayama, Sachio Matsushita, Haruo Kashima, and Susumu Higuchi; (5) ADH2 polymorphism, alcohol drinking, and birth defects, by Lucinda Carr, D. Viljoen, L. Brooke, T. Stewart, T. Foroud, J. Su, and Ting-Kai Li; and (6) ADH genotypes and alcohol use in Europeans, by John B. Whitfield.

Adult↗
PubMed2001

Patterns of cognitive-motor development in children with fetal alcohol syndrome from a community in South Africa.

BACKGROUND: Even though fetal alcohol syndrome (FAS) has been reported in nonwestern nations, there is a paucity of information on neurodevelopment in the affected children from those nations. This article reports on a study of cognitive-motor development in a group of children with FAS from a community in the Western Cape Province in South Africa. METHODS: Thirty-four children with FAS and 34 controls from grade 1 (school entry level) classes participated. The two groups comprised Afrikaans-speaking children of mixed ancestry (South African Colored) and were matched for age, sex, and family income. The Griffiths Mental Development Scales were used to assess cognitive motor development of the participants. RESULTS: A multivariate analysis of covariance was performed to test the group effect on the combined Griffiths subscales adjusting for maternal education. The results showed a significant group effect. Follow-up analyses revealed that a combination of four subscales (Speech and Hearing, Performance, Practical Reasoning, and Eye and Hand Coordination) primarily contributed to the overall effect. Although there was a marginal effect on the Personal-Social subscale, no significant effect on the Locomotor (gross motor) subscale was found. CONCLUSIONS: The results showed that the FAS group was markedly deficient only in higher-order cognitive-motor competencies.

Child↗
PubMed2000

A 500-kb region on chromosome 16p13.1 contains the pseudoxanthoma elasticum locus: high-resolution mapping and genomic structure.

We have recently mapped the genetic defect underlying pseudoxanthoma elasticum (PXE), an inherited disorder characterized by progressive calcification of elastic fibers in skin, eye, and cardiovascular system, to chromosome 16p 13.1. Here we report further data on the fine-mapping and genomic structure of this locus. Haplotype analysis of informative PXE families narrowed the locus to an interval of less than 500 kb located between markers D16B9621 and D16S764. Three overlapping YAC clones were found to cover this region through YAC-STS content mapping. An overlapping BAC contig was then constructed to cover this interval and the surrounding region. About 80% of this chromosomal region has been fully sequenced using the BAC shotgun technique. Gene content and sequence analysis predicted four genes (MRP1, MRP6, PM5, and a novel transcript) and two pseudogenes (ARA and PKDI) within this interval. By screening a somatic cell hybrid panel we were able to precision-map the breakpoint of Cy185 and the starting point of a chromosomal duplication within 20 kb of BAC A962B4. The present data further refine the localization of PXE, provide additional physical cloning resources, and will aid in the eventual identification of the genetic defect causing PXE.

Adult↗
PubMed2000

Mutations of the gene encoding the transmembrane transporter protein ABC-C6 cause pseudoxanthoma elasticum.

We recently published the precise chromosomal localization on chromosome 16p13.1 of the genetic defect underlying pseudoxanthoma elasticum (PXE), an inherited disorder characterized by progressive calcification of elastic fibers in skin, eye, and the cardiovascular system. Here we report the identification of mutations in the gene encoding the transmembrane transporter protein, ABC-C6 (also known as MRP-6), one of the four genes located in the region of linkage, as cause of the disease. Sequence analysis in four independent consanguineous families from Switzerland, Mexico, and South Africa and in one non-consanguineous family from the United States demonstrated several different mis-sense mutations to cosegregate with the disease phenotype. These findings are consistent with the conclusion that PXE is a recessive disorder that displays allelic heterogeneity, which may explain the considerable phenotypic variance characteristic of the disorder.

ATP-Binding Cassette Transporters↗
PubMed2000

Epidemiology of fetal alcohol syndrome in a South African community in the Western Cape Province.

OBJECTIVES: This study determined the characteristics of fetal alcohol syndrome in a South African community, and methodology was designed for the multidisciplinary study of fetal alcohol syndrome in developing societies. METHODS: An active case ascertainment, 2-tier methodology was used among 992 first-grade pupils. A case-control design, using measures of growth, development, dysmorphology, and maternal risk, delineated characteristics of children with fetal alcohol syndrome. RESULTS: A high rate of fetal alcohol syndrome was found in the schools--40.5 to 46.4 per 1000 children aged 5 to 9 years--and age-specific community rates (ages 6-7) were 39.2 to 42.9. These rates are 18 to 141 times greater than in the United States. Rural residents had significantly more fetal alcohol syndrome. After control for ethnic variation, children with fetal alcohol syndrome had traits similar to those elsewhere: poor growth and development, congruent dysmorphology, and lower intellectual functioning. CONCLUSIONS: This study documented the highest fetal alcohol syndrome rate to date in an overall community population. Fetal alcohol syndrome initiatives that incorporate innovative sampling and active case ascertainment methods can be used to obtain timely and accurate data among developing populations.

Age Distribution↗
PubMed1999

Alcohol consumption by pregnant women in the Western Cape.

OBJECTIVE: To assess alcohol use by pregnant women in three underprivileged areas of the Western Cape. DESIGN: Data were collected from subjects, selected in a randomised manner, during a single, structured interview. SUBJECTS AND SETTING: Interviews were conducted among pregnant women voluntarily attending selected antenatal clinics in the George/Oudtshoorn, Vredenburg/Saldanha, and Cape Metropole areas of the Western Cape. OUTCOME MEASURES: On completion of the interview, women at risk were counselled with regard to the dangers of prenatal alcohol exposure to the fetus. RESULTS: 42.8% of the women in the sample admitted to varying degrees of alcohol ingestion during the current pregnancy. The reported alcohol intake of over 55% of these women, i.e. 23.7% of the sample, was sufficient to place their unborn children at high risk for the fetal alcohol syndrome (FAS). These heavy drinkers followed a pattern of binge drinking over weekends and showed a marked preference for beer. Combined alcohol and tobacco use occurred in 29.6% of the sample. Only one subject admitted to using marijuana. CONCLUSION: The data in this study confirm that a high rate of alcohol and tobacco use prevails among pregnant women in poorer communities of the Western Cape. Extrapolating from experience, as many as 9.5% of the sample may produce children with FAS.

Adult↗
PubMed1997

Mseleni and Handigodu familial osteoarthropathies: syndromic identity?

Mseleni joint disease (MJD) and Handigodu joint disease (HJD) are familial skeletal disorders that affect several hundred persons in northern Zululand, South Africa and in the Shimoga district of southern India, respectively. Severe precocious, progressive degenerative osteoarthropathy, which occurs in both conditions, causes marked physical handicap by adulthood. The clinical and radiological manifestations of MJD and HJD are very similar and it is possible that they represent the same entity. HJD appears to be inherited as an autosomal dominant trait, while MJD clusters in families without a definite Mendelian pattern. It is possible that an environmental factor is active in the pathogenesis of both disorders and comparative investigations would be fruitful. The predominance of severe degenerative osteoarthropathy in both disorders may have important implications for the elucidation of the pathogenesis of the common conventional forms of osteoarthropathy.

Body Height↗
PubMed1997

Twenty-year birth prevalence of Down syndrome in Cape Town, South Africa.

The 20-year birth prevalence of Down syndrome in Cape Town, South Africa, was determined. All cases delivered to mothers in Cape Town, plus terminations following prenatal diagnosis, between 1 January 1974 and 31 December 1993 were ascertained. There were 784 Down syndrome pregnancies, of which 95% were trisomies. The 32 terminations comprised 18.3% of the white, 5.8% of the coloured (mixed race) and 1.4% of the black cases. The overall prevalence rate was 1.49 per 1000 (white 1.88, coloured 1.54 and black 1.29 per 1000). Analysis for linear trends showed a significant decline in rates for the total population and for whites, a downward trend for coloureds, but no decline for blacks. Over the last 5-year period the prevalence rates in all three population groups were 1.3 per 1000. An increasing risk with advancing maternal age was confirmed, but no maternal age-specific differences in rates by race were demonstrated.

Abortion, Induced↗
PubMed1997

Familial streptomycin ototoxicity in a South African family: a mitochondrial disorder.

The vestibular and ototoxic effects of the aminoglycoside antibiotics (streptomycin, gentamycin, kanamycin, tobramycin, neomycin) are well known; streptomycin, in particular, has been found to cause irreversible, profound, high frequency sensorineural deafness in hypersensitive persons. Aminoglycoside ototoxicity occurs both sporadically and within families and has been associated with a mitochondrial DNA (mtDNA) 1555A to G point mutation in the 12S ribosomal RNA gene. We report on the molecular analysis of a South African family with streptomycin induced sensorineural deafness in which we have found transmission of this same predisposing mutation. It is now possible to identify people who are at risk of hearing loss if treated with aminoglycosides in the future and to counsel them accordingly. In view of the fact that aminoglycoside antibiotics remain in widespread use for the treatment of infections, in particular for tuberculosis, which is currently of epidemic proportions in South Africa, this finding has important implications for the family concerned. In addition, other South African families may potentially be at risk if they carry the same mutation.

Anti-Bacterial Agents↗
PubMed1996

Patient attitudes to prenatal screening and termination of pregnancy at Groote Schuur Hospital: a two year prospective study.

A prospective 2-year study involving a questionnaire administered by a Genetic Counsellor was carried out to ascertain patient attitudes to prenatal screening and termination of pregnancy (TOP) at Groote Schuur Hospital. Women were questioned regarding their religious affiliation, education, ethnic group, reason for referral and age. Following ultrasonography, non-directive counselling was given regarding amniocentesis and TOP. Four hundred and sixty six women were investigated of whom 74% were of mixed ancestry, 14% Black and 12% White. Three hundred and sixteen persons were offered amniocentesis (67.8%). Muslim women accepted less frequently (66%) than other religious affiliations (79.7%) (p = 0.025). Overall amniocentesis acceptance was 75.9%. TOP was performed in 45 pregnancies (9.7%). Muslim women accepted TOP 1.33 times (C.I. 0.32-5.6) more frequently than those of other religious persuasions. Overall TOP acceptance rate was 76.3%. The mixed ethnic population of pregnant women seen at Groote Schuur Hospital readily accept prenatal screening and TOP following non-directive genetic counselling. The introduction of prenatal screening programmes for the prevention of severe congenital defects in this population would be successful and cost-effective.

Abortion, Therapeutic↗
PubMed1996

Mseleni joint disease--a molecular genetic approach to defining the aetiology.

Mseleni joint disease (MJD) is an unusual form of progressive and widespread degenerative osteoarthropathy that has been identified in several hundred people in the remote Mseleni region of northern Zululand. Affected individuals experience articular discomfort in childhood and may be seriously handicapped as adults, often requiring prosthetic hip joint replacement. Although the condition clusters in families, there is no evidence of Mendelian inheritance and assessment of affected kindreds has not shown any evidence of genomic imprinting. To date our molecular work-up has entailed the study of 47 affected individuals from MJD kindreds to investigate familial predisposition based on the inheritance of a subset of markers and/or genes on the human genome, particularly those associated with the cartilage matrix. In addition, we have collected blood specimens form 111 unaffected but unrelated individuals from the same population group in order to determine whether any relationship exists between genetic components of the human leucocyte antigen (HLA) system and the MJD phenotype. Our investigations show the following: (i) there is no association between MJD and the HLA system which has previously been associated with non-Mendelian genetic conditions; (ii) COL2A1, which has been implicated in some forms of spondylo-epiphyseal dysplasia, may be involved in at least a subset of MJD patients; and (iii) type VI collagen is overabundant in degenerated hip joint cartilage.

Black People↗
PubMed1995

Localization of the Schwartz-Jampel syndrome (SJS) locus to chromosome 1p34-p36.1 by homozygosity mapping.

Schwartz-Jampel syndrome (SJS, MIM 255800), also known as chondrodystrophic myotonia, is a rare autosomal recessive disorder characterized by generalized myotonia, skeletal abnormalities and facial dysmorphism. Using homozygosity mapping, we localized the SJS locus to chromosome 1p34-p36.1 in a 8 cM interval flanked by markers D1S199 and D1S234. Families of different ethnic backgrounds (Tunisia and South Africa) showed genetic linkage to the same locus. Moreover, one Algerian family also demonstrated evidence of genetic linkage to 1p34-p36.1. Taken altogether, our results suggest genetic homogeneity, at least in the group of families analyzed.

Chromosome Mapping↗