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Biomedical subjects

D Curtis

Publications and source records attributed to D Curtis.

207 records · Page 12Linked to original sources
PubMedDate not supplied

Family association studies of markers on chromosome 2q and Type 1 diabetes in subjects from South India.

BACKGROUND: Several Type 1 diabetes susceptibility loci have been located to chromosome 2q12-21. However, results have not always been consistent and this may reflect study design and the population analysed. We have used a family-based design to look for an association between Type 1 diabetes and markers located to 2q12-21. METHODS: Ninety-one South Indian families consisting of subjects with Type 1 diabetes and their parents were genotyped for eight polymorphic markers localised to 2q12-21, which includes the interleukin-1 gene cluster. Radiation hybrid mapping was used to localise the map position of D2S308 and D2S363 on 2q12-21. The extended transmission disequilibrium test was used for statistical analysis. RESULTS: No associations were found between Type 1 diabetes and markers located in and around the interleukin-1 gene cluster or the interleukin-1 Type 1 receptor. In contrast, a suggestive association was found between Type 1 diabetes and two closely-linked markers telomeric of the interleukin-1 gene cluster (D2S308 and D2S363, separated by 3.3 cR) (p=0.004 and p=0.002, respectively). CONCLUSION: This preliminary study suggests that a locus close to D2S308 and D2S363 is involved in the aetiology of Type 1 diabetes in the South Indian population.

Adolescent↗
PubMedDate not supplied

Emerging issues and future needs in humanitarian assistance.

During the past two decades, there has been tremendous investment in the ability to intervene in disaster settings, and significant barriers remain to providing appropriate services to populations affected by natural and man-made calamities. Many of the barriers to providing effective assistance exist within the NGO community, and illustrate emerging needs for international agencies. These emerging needs include improving methods of recipient participation to promote the local health system, developing improved methods for quality assurance, enhancing options for personnel development, and addressing long-term needs of reconstruction and rehabilitation. Relief agencies face challenges on all levels to develop sound practices in providing humanitarian assistance that can lead to long-term benefits to populations affected by disaster.

Altruism↗
PubMedDate not supplied

Model-free analysis and permutation tests for allelic associations.

In this short report, we address some practical problems in performing likelihood-based allelic association analysis of case-control data. Model-free statistics are proposed and their properties assessed by simulation, and procedures based on permutation tests are described for marker-marker as well as marker-disease associations. A memory-efficient algorithm is developed which enables several highly polymorphic markers to be analysed.

Algorithms↗
PubMedDate not supplied

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency: the prevalent mutation G985 (K304E) is subject to a strong founder effect from northwestern Europe.

Medium-chain acyl CoA dehydrogenase (MCAD) deficiency is a potentially fatal inherited defect of fatty acid beta-oxidation. Approximately 90% of the disease-causing alleles in diagnosed patients are due to a single base mutation, an A (adenine) to G (guanine) transition at position 985 of MCAD cDNA (G985). In a limited number of cases it was found that this mutation was always associated with a particular haplotype, defined by three intragenic restriction fragment length polymorphisms, indicating a founder effect [Kølvraa et al.; Hum Genet 1991; 87: 425-429]. In addition, recent studies of American patients and their ancestors suggested the existence of a founder from northern Europe [Yokota et al.; Am J Hum Genet 1991; 49: 1280-1291]. In the present study we document (1) that the G985 heterozygous frequency in the Caucasian population of North Carolina in the USA is 1/84, which is 5- to 10-fold higher than in non-Caucasian Americans; (2) that there exists a 100% association of the G985 mutation in 17 families with MCAD-deficient patients to a certain haplotype, defined by the restriction endonucleases BanII, PstI and TaqI; (3) that MCAD deficiency due to the G985 mutation is more frequent in the Netherlands, Ireland, England, Belgium and Denmark than in other western European countries, and (4) that the frequency distribution of G985 mutation carriers is 1/68-1/101 in newborns in the United Kingdom and Denmark, and 1/333 in Italy. These results support the notion of a founder effect in northwestern Europe.

Acyl-CoA Dehydrogenase↗
PubMedDate not supplied

A procedure for combining two-point lod scores into a summary multipoint map.

Multipoint linkage analysis can be extremely demanding in terms of computer time and memory, and these requirements rise exponentially with the number of markers used. A method is described for producing a rapid approximation to a multipoint analysis from the supplied results of two-point analyses with each marker. The method depends on regarding the lod scores as if they were obtained from a number of independent phase-known meioses, and making estimates concerning the proportion of all meioses which are likely to be informative for each marker. It then becomes possible to estimate the amount of information from each marker or pair of markers which is independent of information from other markers. The lod scores arising from independent contributions may then be summed to approximate the true multipoint lod score. The method has been implemented in a computer program called FASTMAP which is freely available. It has been tested on a variety of simulated and real data. In most circumstances it performs well, with a high correlation between the estimated and true multipoint lod score and little bias. However occasionally the results of the estimate deviate markedly from the multipoint lod score, especially at map positions very close to the markers. The overall usefulness of the method will therefore need to be further evaluated, but it does seem adequate at least for building exclusion maps and carrying out preliminary and exploratory analyses.

Bipolar Disorder↗
PubMedDate not supplied

Microsatellite polymorphisms for chromosome 5 bands q11.2-q13.3.

The genes for spinal muscular atrophy (SMA) and a possible subtype of schizophrenia (SCZD1) have been mapped to chromosome 5q11.2-q13.3. DNA markers have been mapped to 5q11.2-q13.3 using a hybrid cell line deleted for this region [Gilliam et al., Genomics 1989;5:940-944]. Genomic lambda clones for these markers facilitated the identification of highly polymorphic microsatellites. A total of ten microsatellites were identified and sequenced. Of these, seven were found to be polymorphic. Four had polymorphism information content values > 0.7. New polymorphic microsatellites were sequenced for D5S76, D5S125, D5S39, D5S127 and HEX-B. Two-point and multipoint analysis in non-CEPH pedigrees confirmed that the microsatellites were in tight linkage with each other. These new microsatellites will increase the efficiency of linkage analysis for these disorders.

Alleles↗
PubMedDate not supplied

Linkage analysis of manic depression (bipolar affective disorder) in Icelandic and British kindreds using markers on the short arm of chromosome 18.

Attempts were made to follow up results of a previous linkage study which suggested that a locus-modifying susceptibility to bipolar and related unipolar affective disorder might be present in the pericentromeric region of the short arm of chromosome 18. Twenty-three multiply affected pedigrees collected from Iceland and the UK were genotyped using three highly polymorphic microsatellite markers at D18S37, D18S40 and D18S44 which span the region implicated. Lod score analyses under the assumption of heterogeneity and non-parametric linkage analyses were performed. The total lod scores obtained were strongly negative, and analysis allowing for heterogeneity did not suggest that any subgroup of the families was linked. Model-free linkage analysis using extended relative pair analysis and MFLINK also failed to detect any evidence for linkage. Our study provides no support for the presence of a locus-modifying genetic susceptibility to bipolar affective disorder in the pericentromeric region of chromosome 18q11. Further analyses in independent samples should help to reveal whether our negative results are due to locus heterogeneity or whether the original results were false-positive.

Alleles↗