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At least 145 records · Page 8Linked to original sources
PubMed1986

Further data supporting linkage between cystic fibrosis and the met oncogene and haplotype analysis with met and pJ3.11.

The linkage of cystic fibrosis (CF) and the polymorphic DNA markers pJ3.11, met, 7C22, DOCR1-917, COL1A2, and TCRB have jointly localized the mutation causing CF to chromosome 7q2.1-3.1. We report further linkage data with two polymorphic markers at the met oncogene locus, pmetH and pmetD, which supports the tight linkage found by White et al. between CF and met. One family shows evidence for meiotic recombination between CF and met. Analysis of haplotypes in CF pedigrees collected for linkage studies combined with data from single affected families requesting prenatal diagnosis (Farrall et al., Lancet i:1402-1404, 1986) shows CF and met to be in linkage equilibrium in our population while pJ3.11-CF haplotypes show a deviation from the equilibrium frequencies.

Cystic Fibrosis↗
PubMed1990

Linkage analysis assuming a single-locus mode of inheritance for traits determined by two loci: inferring mode of inheritance and estimating penetrance.

What happens to the results of linkage analysis when one assumes that a disease results from a single genetic locus with reduced penetrance when the actual cause is two epistatically interacting loci? We wanted to (1) determine whether assuming the correct mode of inheritance at the linked locus leads to a higher lod score than assuming the incorrect mode of inheritance irrespective of penetrance assumptions and (2) determine whether it is possible to estimate the apparent penetrance due to the second, unlinked locus from the linkage data. Linkage data were simulated under three different two-locus models. Different "penetrances" were simulated by using different disease allele frequencies at the unlinked locus. Data were then analyzed assuming a single locus with reduced penetrance. The maximum lod score was maximized with respect to penetrance (LVP curves). We found that if there were enough data, assuming the correct (i.e., generating) mode of inheritance at the linked locus always led to a higher lod score than assuming the incorrect mode of inheritance no matter what the penetrance assumption. In contrast to the case where reduced penetrance is due to random factors, the estimate of the apparent penetrance (the "penetrance" due to the second locus) was biased, thus making any estimation of the gene frequency at the second locus doubtful. The ability to detect linkage was apparently not affected when the effects of the second locus were treated as random reduced penetrance. The results suggest that analyzing the data under the assumption of a single-locus model with reduced penetrance rather than a two-locus model will not substantially decrease the ability to establish linkage nor will it affect determining the mode of inheritance at the linked locus from the linkage data.

Computer Simulation↗
PubMed2002

Linkage disequilibrium mapping with genotype data.

Linkage disequilibrium mapping has proven a powerful tool for locating disease genes. Although all existing linkage disequilibrium mapping methods implicitly assume that individual haplotypes can be inferred, only genotypes are directly observable in practice, and haplotypes cannot always be uniquely resolved based on genotype data. In this article, we propose a likelihood-based linkage disequilibrium mapping approach to analyzing multilocus genotype data arising from case-control studies. Results from extensive simulation studies suggest that this approach may be a useful tool to fine map disease genes using case-control data.

Chromosome Mapping↗
PubMed2006

Characteristics of unmatched maternal and baby records in linked birth records and hospital discharge data.

Linkage of routinely collected health data collections is increasingly being used to investigate maternal and infant morbidity and mortality. Such data have the advantage of being population based and readily available. However, in using such data it is important to understand the data linkage process, the proportions of unmatched records and the characteristics of these records so that potential bias can be recognised. This article describes the differences in characteristics of matched and unmatched mothers' and babies' records generated in the linkage of birth records with hospital discharge data and explores some of the reasons for these differences. The study population included over 250,000 women and their babies discharged from hospital following delivery in New South Wales, Australia between 1 January 2000 and 31 December 2002. Hospital discharge and birth data were linked using probabilistic linkage methods for both mothers and babies. Matching rates were 98.5% and 99.0% for maternal birth and hospital discharge records, respectively, and 98.8% and 99.4% for baby records. Unmatched maternal records had higher proportions of Australian-born women, private hospital births and stillbirths compared with matched records. Unmatched baby records had higher proportions of low-birthweight babies, preterm births and in-hospital deaths than matched records. With the possible exception of stillbirths, these differences are unlikely to cause important bias in studies relying on matched records only. Our results suggest studies using linked data should generally examine and report on the characteristics of unmatched records, and recognise them as a potential source of bias.

Bias↗
PubMed2004

Linkage analysis of ordinal traits for pedigree data.

Linkage analysis is used routinely to map genes for human diseases and conditions. However, the existing linkage-analysis methods require that the diseases or conditions either be dichotomized or measured by a quantitative trait, such as blood pressure for hypertension. In the latter case, normality is generally assumed for the trait. However, many diseases and conditions, such as cancer and mental and behavioral conditions, are rated on ordinal scales. The objective of this study was to establish a framework to conduct linkage analysis for ordinal traits. We propose a latent-variable, proportional-odds logistic model that relates inheritance patterns to the distribution of the ordinal trait. We use the likelihood-ratio test for testing evidence of linkage. By means of simulation studies, we find that the power of our proposed model is substantially higher than that of the binary-trait-based linkage analysis and that our test statistic is robust with regard to certain parameter misspecifications. By using our proposed method, we performed a genome scan of the hoarding phenotype in a data set with 53 nuclear families, which were collected by the Tourette Syndrome Association International Consortium for Genetics (TSAICG). Standard linkage scans using hoarding as a dichotomous trait were also performed by using GENEHUNTER and ALLEGRO. Both GENEHUNTER and ALLEGRO failed to reveal any marker significantly linked to the binary hoarding phenotypes. However, our method identified three markers at 4q34-35 (P = 0.0009), 5q35.2-35.3 (P = 0.0001), and 17q25 (P = 0.0005) that manifest significant allele sharing.

Genetic Linkage↗
PubMed1999

[Linking survey data with routine health and accident insurance data].

Data of the social security institutions, although gathered for administrative purposes, provide important information on work-related morbidity. The validity of the data can be improved by linking several data sources and data from questionnaires or medical examinations. Hence, within the framework of the "Cooperative Programme Occupation and Health" (KOPAG) a specific procedure for data linkage was developed. Data linkage was effected via an anonymous social security number on the one hand, and on the other hand a constructed short number using informations on birthday, sex, and the first letter of the surname of the employees. By means of this short number an average 62% of the questionnaires could be linked to the health insurance sickness leave data. Data linkage was particularly successful (85%) under specific advantageous conditions. Data linkage failed in 25% of all cases because the information necessary to construct the short number was obviously wrong. In general, this procedure to link survey data to routine data of the social security proves suitable for use in routine health reporting.

Accidents, Occupational↗
PubMed2006

Testing groups of genomic locations for enrichment in disease loci using linkage scan data: a method for hypothesis testing.

Genes for complex disorders have proven hard to find using linkage analysis. The results rarely reach the desired level of significance and researchers often have failed to replicate positive findings. There is, however, a wealth of information from other scientific approaches which enables the formation of hypotheses on groups of genes or genomic regions likely to be enriched in disease loci. Examples include genes belonging to specific pathways or producing proteins interacting with known risk factors, genes that show altered expression levels in patients or even the group of top scoring locations in a linkage study. We show here that this hypothesis of enrichment for disease loci can be tested using genome-wide linkage data, provided that these data are independent from the data used to generate the hypothesis. Our method is based on the fact that non-parametric linkage analyses are expected to show increased scores at each one of the disease loci, although this increase might not rise above the noise of stochastic variation. By using a summary statistic and calculating its empirical significance, we show that enrichment hypotheses can be tested with power higher than the power of the linkage scan data to identify individual loci. Via simulated linkage scans for a number of different models, we gain insight in the interpretation of genome scan results and test the power of our proposed method. We present an application of the method to real data from a late-onset Alzheimer's disease linkage scan as a proof of principle.

Alzheimer Disease↗
PubMed2004

Surgical-site infections after orthopaedic surgery: statewide surveillance using linked administrative databases.

Prospective surveillance programmes to monitor the incidence of surgical-site infection (SSI) in patients who have had orthopaedic implant surgery can be difficult to implement due to limited human and technical resources. In addition, prolonged patient follow-up, up to one year, may be required. Traditional methods of surveillance can be enhanced by using administrative databases to assist in case finding and facilitate overall surveillance activities. The aim of this study was to identify the incidence of SSI in patients who had undergone total hip replacement (THR) or total knee replacement (TKR) surgery in all Western Australian (WA) hospitals during 1999 using the Western Australian Data Linkage System. The WA Data Linkage System links several population-based administrative health datasets within the state, including the Hospital Morbidity Data System (HMDS), containing International Classification of Disease-coded discharge information, and mortality records. A total of 1476 THR and 1875 TKR procedures was identified from 21 WA hospitals during 1999. The incidence of SSI after these procedures was 5% (95% CI 4.3-5.7) [THR (4.86%, 95% CI 3.77-5.95) and TKR (5.15%, 95% CI 4.15-6.15)]. The incidence was 33.72 infections per 1000 person-years. Patients aged over 80 years experienced a significantly higher rate of infection after THR compared with patients aged 80 or less (z-test, z = 2.56, P = 0.015), but not for TKR. No patients with an SSI died during follow-up. The WA Data Linkage System provided a unique opportunity to review the incidence of SSIs in patients undergoing THR or TKR surgery in WA hospitals.

Adult↗
PubMed1978

Analysis of linkage between the major histocompatibility system and juvenile, insulin-dependent diabetes in multiplex families. Reanalysis of data.

Linkage analysis between the major histocompatibility system (HLA) and juvenile, insulin-dependent diabetes, assuming an autosomal recessive mode and 50% penetrance was performed on 21 juvenile, insulin-dependent diabetic multiplex families (two or more diabetics per sibship) with phenotypically normal parents. The total lod score was the highest (3.98) at a recombination fraction of 13%. For a penetrance of 100%, the highest total lod score was 2.92 at a recombination fraction of 18%. These results are compatible with the existence of linkage between an autosomal recessive diabetic gene with 50% penetrance and the HLA in some of the families studied. Our ascertainment strategy would be expected to increase the likelihood of selecting for genetically homogenous diabetes and against sporadic forms of the disease. Thus, our findings may apply only to a small proportion of all cases of juvenile, insulin-dependent diabetes.

Diabetes Mellitus, Type 1↗
PubMed1988

The couch and the cloth: the need for linkage.

Data from the Epidemiologic Catchment Area study were used to compare the demographic characteristics and psychiatric symptomatology of persons classified into four groups based on source of mental health services: clergy only, mental health specialists only, both clergy and mental health specialists, and neither source. Those receiving services from both clergy and mental health specialists were more likely to have major affective and panic disorders than those who sought services from clergy or mental health specialists only or who sought services from neither. Those in the care of mental health specialists were more likely to have substance abuse disorders. Those in the care of clergy only were as likely as those seeing mental health specialists only to have serious mental disorders. The data make clear the need for formal linkages between clergy and mental health professionals.

Adolescent↗
PubMed2004

Methods for identifying pregnancy-associated deaths: population-based data from Finland 1987-2000.

To find maternal and pregnancy-related deaths, it is important that all pregnancy-associated deaths are identified. This article examines the effect of data linkages between national health care registers and complete death certificate data on pregnancy-associated deaths. All deaths among women of reproductive age (15-49 years) in Finland during the period 1987-2000 (n = 15 823) were identified from the Cause-of-Death Register and linked to the Medical Birth Register (n = 865 988 births), the Register on Induced Abortions (n = 156 789 induced abortions), and the Hospital Discharge Register (n = 118 490 spontaneous abortions) to determine whether women had been pregnant within 1 year before death. The death certificates of the 419 women thus identified were reviewed to find whether the pregnancy or its termination was coded or mentioned. In total, 405 deaths (96.7%) were identified in registers other than the Cause-of-Death Register. Without data linkages, 73% of all pregnancy-associated deaths would have been missed; the percentage after induced and spontaneous abortions was even higher. Data linkages to national health care registers provide better information on maternal deaths and pregnancy-associated deaths than death certificates alone. If possible, pregnancies not ending in a live birth should be included in the data linkages.

Abortion, Induced↗