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At least 199 records · Page 11Linked to original sources
PubMed1999

X linked mental retardation and infantile spasms in a family: new clinical data and linkage to Xp11.4-Xp22.11.

In order to describe the neurological abnormalities and to identify the gene localisation, we re-evaluated a previously reported family with X linked mental retardation (XLMR). Reliable data were obtained for six of the seven affected males, of whom two had had infantile spasms. Profound MR (IQ<20) was found in one and mild MR (IQ 50-70) in five males. No dysmorphic features, except for macrocephaly in one male, were found. Neurological abnormalities included varying degrees of spinocerebellar involvement. Neuroimaging studies showed abnormalities, such as cerebellar atrophy or corpus callosum hypoplasia or both, in three of the six males. Several affected and unaffected subjects suffered from hyperhidrosis, which appeared to segregate independently as an autosomal dominant trait. Genetic linkage analysis localised the XLMR disease gene to Xp11.4-Xp22.11 with a maximum multipoint lod score of 3.57, overlapping the candidate region recently found in two Belgian XLMR-infantile spasm families. Compared to the Belgian patients, the majority of the affected males in this report had a considerably milder phenotype.

Adolescent↗
PubMed2005

Mutations in apoptosis-related gene, PDCD10, cause cerebral cavernous malformation 3.

OBJECTIVE: To identify the CCM3 gene in a population of 61 families with a positive family history of cerebral cavernous malformations (CCM), 8 of which had suggestive linkage to the CCM3 locus. METHODS: We searched for mutations within the CCM3 interval using a high-throughput screening technique, temperature-gradient capillary electrophoresis. Mutations detected by this device were subsequently sequenced, and the results were analyzed. RESULTS: A recent study by Bergametti et al. established Programmed Cell Death 10 (PDCD10) as the gene responsible for CCM3. We hereby confirm PDCD10 as the CCM3 gene by reporting four novel mutations in 61 CCM families. Two of these mutations were identical and produced a stop codon in exon 7. Another two resulted in frameshift mutations in exon 6, although the mutations occurred at different points along the exon. The last mutation caused a frameshift in exon 9. Of note, mutations in these families completely cosegregated with the trait. Three of the five families had prior linkage data suggestive of the CCM3 locus, whereas the remaining two were identified in index patients with a positive family history but no linkage data. CONCLUSION: Our data establish PDCD10 as the gene responsible for CCM in families linking to the CCM3 locus. The discovery of the third gene involved in inherited forms of CCM, after KRIT1 and Malcavernin, is an important step toward dissecting the molecular pathophysiology of this disease.

Apoptosis Regulatory Proteins↗
PubMed2007

Readmission and survival following hospitalization for chronic obstructive pulmonary disease: long-term trends.

BACKGROUND: Exacerbations requiring hospital admission for chronic obstructive pulmonary disease (COPD) contribute to a decline in health status and are costly to the community. Long-term trends in admissions and associated outcomes are difficult to establish because of frequent readmissions, high case fatality and potential diagnostic transfer between COPD and asthma. The Western Australian Data Linkage System provides a unique opportunity to examine admissions for patients with COPD over the long term. METHOD: Nineteen years of hospital morbidity data, based on International Classification of Diseases-9 criteria were extracted from the Western Australian Data Linkage System (1980-1998) and merged with mortality records to examine trends in hospital admissions for COPD. RESULTS: The rate of hospital admissions for COPD has declined overall and the rate of first presentation declined in men and remained constant in women. The risk of readmission increased throughout the period (P < 0.0001) and more than half of all admissions were followed by readmission within a year. Median survival following first admission was 6 years (men 5 years; women 8 years). Age, sex and International Classification of Diseases subcategory each showed an independent effect on the risk of mortality (P < 0.0001). The poorest survival was in patients subcategorized as emphysema. For patients with multiple admissions, the likelihood of cross-over between COPD and asthma was high and increased with the total number of admissions. CONCLUSION: The rate of admission for COPD has declined in Western Australia; however, the resource burden will continue to increase because of the ageing population. This has policy implications for the development of acute care treatment programmes for COPD.

Adult↗
PubMed2005

The effect of missing data on linkage disequilibrium mapping and haplotype association analysis in the GAW14 simulated datasets.

We used our newly developed linkage disequilibrium (LD) plotting software, JLIN, to plot linkage disequilibrium between pairs of single-nucleotide polymorphisms (SNPs) for three chromosomes of the Genetic Analysis Workshop 14 Aipotu simulated population to assess the effect of missing data on LD calculations. Our haplotype analysis program, SIMHAP, was used to assess the effect of missing data on haplotype-phenotype association. Genotype data was removed at random, at levels of 1%, 5%, and 10%, and the LD calculations and haplotype association results for these levels of missingness were compared to those for the complete dataset. It was concluded that ignoring individuals with missing data substantially affects the number of regions of LD detected which, in turn, could affect tagging SNPs chosen to generate haplotypes.

Chromosome Mapping↗
PubMed2001

Two families with phenotypically different hereditary low frequency hearing impairment: longitudinal data and linkage analysis.

Two families with low frequency hearing impairment have been described previously. Family A (Danish) presented a sensorineural hearing impairment most pronounced for frequencies below 2 kHz and a pedigree typical for an autosomal dominant trait with complete penetrance (Königsmark type). Family B, originating from the Faroe Islands, showed conflicting audiological test results, making a valid classification impossible. The pedigree suggested autosomal dominant inheritance with incomplete penetrance. The objectives of the present study are to acquire longitudinal audiometric data, to clarify the mode of transmission, and to localize the mutant gene by reevaluation of the two families. The methods used are evaluation of the family history, audiological examination and linkage analysis. In family A, update of the pedigree fitted the assumption of an autosomal dominant mode of transmission. In six examined subjects audiological data were available from the previous study. The median progression over a 13-21-year period was 13.8 dB HL for the thresholds, averaged across 0.5, 1, 2 and 4 kHz and 17.5 dB HL for the thresholds, averaged across 2 and 4kHz. In family B, the probable mode of transmission is autosomal dominant with reduced penetrance. In this family no progression of the hearing impairment was found. Linkage analysis of family A showed a lod score of 3.53, indicating significant linkage to the loci DFNA6 and DFNA14 on chromosome 4, previously found to be involved in low frequency hearing impairment. Family B was not linked to the region on chromosome 4, further adding to the genetic heterogeneity in low frequency sensorineural hearing impairment.

Adult↗
PubMed1994

Using lod-score differences to determine mode of inheritance: a simple, robust method even in the presence of heterogeneity and reduced penetrance.

Determining the mode of inheritance is often difficult under the best of circumstances, but when segregation analysis is used, the problems of ambiguous ascertainment procedures, reduced penetrance, heterogeneity, and misdiagnosis make mode-of-inheritance determinations even more unreliable. The mode of inheritance can also be determined using a linkage-based method (maximized maximum lod score or mod score) and association-based methods, which can overcome many of these problems. In this work, we determined how much information is necessary to reliably determine the mode of inheritance from linkage data when heterogeneity and reduced penetrance are present in the data set. We generated data sets under both dominant and recessive inheritance with reduced penetrance and with varying fractions of linked and unlinked families. We then analyzed those data sets, assuming reduced penetrance, both dominant and recessive inheritance, and no heterogeneity. We investigated the reliability of two methods for determining the mode of inheritance from the linkage data. The first method examined the difference (delta) between the maximum lod scores calculated under the two mode-of-inheritance assumptions. We found that if delta was > 1.5, then the higher of the two maximum lod scores reflected the correct mode of inheritance with high reliability and that a delta of 2.5 appeared to practically guarantee a correct mode-of-inheritance inference. Furthermore, this reliability appeared to be virtually independent of alpha, the fraction of linked families in the data set, although the reliability decreased slightly as alpha fell below .50.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1997

Are outcome data regarding the survivors of neonatal care available from routine sources?

AIM: To determine whether existing information and surveillance systems can be used to provide follow up data on groups of infants at increased risk of disability--for example, the survivors of neonatal intensive care. METHODS: A survey was made of maternity, neonatal, and community child health information systems and surveillance programmes in the Trent Regional Health Authority. Children known to have received neonatal intensive care in Trent between 1 August 1992 and 31 July 1993, and a random sample of normal children in two health districts (data quality check) were included. A data linkage study was made to determine whether follow up information about a random sample of infants, known to be at increased risk of poor outcome, could be identified on community child health databases. Two widely accepted datasets (birth and 2 years) were used as standards for this exercise. The quality of data was audited. RESULTS: All clinical items of the birth minimum dataset were routinely recorded by at least one agency in each health district in Trent. Of the descriptive items, only the mother's age on leaving full time education was not collected. At 2 years, all clinical items were collected as part of the routine surveillance programme, but data were recorded using a system which severely limited interpretation. Data quality, in terms of the number of errors introduced at data entry, was very good with only 1.1% of the check items (4/368) incorrectly recorded. Only two districts had organised electronic transfer of data between maternity, neonatal, and community child health systems. The mother's NHS number, although available, was not routinely recorded by any system. The NHS number of the infant was routinely collected by six out of 12 community paediatric services. Data linkage was attempted in six districts with appropriate community child health databases. Just over 70% of the intensive care sample was successfully linked with follow up information on child health systems. CONCLUSIONS: The existing programmes for routine child surveillance could provide outcome data for high risk groups of infants, such as the survivors of neonatal intensive care. However, the present coding system used for data entry is inadequate. Furthermore, rates of identification, without the use of a unique identifier (NHS number) for each subject, are currently insufficient for monitoring health status in later life.

Child Health Services↗
PubMed1989

Risks of fetal cystic fibrosis based on linkage disequilibrium data.

First-trimester prenatal diagnosis of cystic fibrosis depends on tissues being available from a previous affected child for determination of the phase relationship of DNA markers. If no such tissues are available, it is possible to estimate the risks of a couple producing an affected child from the distribution of haplotypes showing linkage disequilibrium with the cystic fibrosis gene. We have calculated all the fetal risk subsets from the various parental haplotype combinations for the restriction fragment length polymorphisms identified by the KM.19/PstI and XV-2c/TaqI systems. We conclude that only in a limited number of parental combinations are the fetal risks sufficiently high or sufficiently low to be used in prenatal diagnosis.

Cystic Fibrosis↗
PubMed1998

Absence of linkage between inflammatory bowel disease and selected loci on chromosomes 3, 7, 12, and 16.

BACKGROUND & AIMS: Linkage data derived from genome-wide scans of inflammatory bowel disease (IBD) sibling-pair families have identified 4 loci on chromosomes 3, 7, 12, and 16 as potential sites for IBD susceptibility genes. The aim of this study was to investigate whether linkage analysis of another independently collected set of sibling pairs with IBD would provide further evidence of linkage between these previously reported loci and IBD. METHODS: Using the MAPMAKER/SIBS program, the segregation of 21 microsatellite marker loci spanning the 4 putative IBD gene loci was analyzed in a study population comprising 161 families with 114 Crohn's disease, 36 ulcerative colitis, and 50 mixed IBD sibling pairs from the Greater Toronto area. RESULTS: The results of multipoint linkage analysis showed no evidence for linkage between IBD and each of the 21 marker loci studied; the logarithm of odds scores in all instances were less than 0.8. These linkage data were found, by exclusion mapping analysis, to exclude values of lambdas ranging from 1.5 to 3.0, depending on the locus evaluated. CONCLUSIONS: The loci previously suggested as representing IBD susceptibility loci are not linked to IBD in the Toronto population examined in this analysis.

Chromosome Mapping↗
PubMed1988

Occupational risks of sinonasal cancer in Denmark.

A new comprehensive data linkage system for the detailed investigation of occupational cancer has been established in the Danish Cancer Registry, providing employment histories back to 1964. All 382 cases of cancers of the sinonasal cavities diagnosed between 1970 and 1984 and kept on file in this data linkage system were analysed using standardised proportional incidence ratios (SPIR) to screen for industrial high risk areas for these malignancies in Denmark. Excess risks were confirmed among men and women employed in the manufacture of footwear and other leather products and of wooden furniture. No risk significantly above expectancy was observed among wood workers outside the furniture making industry. Excess risks were also seen among men in all areas of basic metal industries (SPIR = 184-562) and in a subset of workers in industries producing metal containers (SPIR = 329-600). Most unexpected were raised risks among employees of both sexes in making cocoa, chocolate, and sugar confectionery (SPIR = 535 for men and 860 for women); these, in combination with the observed risks among female employees in canning and preserving fruits and vegetables (SPIR = 778) and in farming (SPIR = 735) may point to a common aetiology. The obscuring effect of mass significance may, however, be another explanation. The new associations discovered in this large scale linkage study must therefore await further confirmation.

Denmark↗
PubMed1993

Genetic linkage analysis in familial breast and ovarian cancer: results from 214 families. The Breast Cancer Linkage Consortium.

Breast cancer is known to have an inherited component, consistent in some families with autosomal dominant inheritance; in such families the disease often occurs in association with ovarian cancer. Previous genetic linkage studies have established that in some such families disease occurrence is linked to markers on chromosome 17q. This paper reports the results of a collaborative linkage study involving 214 breast cancer families, including 57 breast-ovarian cancer families; this represents almost all the known families with 17q linkage data. Six markers on 17q, spanning approximately 30 cM, were typed in the families. The aims of the study were to define more precisely the localization of the disease gene, the extent of genetic heterogeneity and the characteristics of linked families and to estimate the penetrance of the 17q gene. Under the assumption of no genetic heterogeneity, the strongest linkage evidence was obtained with D17S588 (maximum LOD score [Zmax] = 21.68 at female recombination fraction [theta f] = .13) and D17S579 (Zmax = 13.02 at theta f = .16). Multipoint linkage analysis allowing for genetic heterogeneity provided evidence that the predisposing gene lies between the markers D17S588 and D17S250, an interval whose genetic length is estimated to be 8.3 cM in males and 18.0 cM in females. This position was supported over other intervals by odds of 66:1. The location of the gene with respect to D17S579 could not be determined unequivocally. Under the genetic model used in the analysis, the best estimate of the proportion of linked breast-ovarian cancer families was 1.0 (lower LOD-1 limit 0.79). In contrast, there was significant evidence of genetic heterogeneity among the families without ovarian cancer, with an estimated 45% being linked. These results suggest that a gene(s) on chromosome 17q accounts for the majority of families in which both early-onset breast cancer and ovarian cancer occur but that other genes predisposing to breast cancer exist. By examining the fit of the linkage data to different penetrance functions, the cumulative risk associated with the 17q gene was estimated to be 59% by age 50 years and 82% by age 70 years. The corresponding estimates for the breast-ovary families were 67% and 76%, and those for the families without ovarian cancer were 49% and 90%; these penetrance functions did not differ significantly from one another.

Adult↗
PubMed2004

Unpacking analyses relying on area-based data: are the assumptions supportable?

BACKGROUND: In the absence in the major Australian administrative health record collections of a direct measure of the socioeconomic status of the individual about whom the event is recorded, analysis of the association between the health status, use of health services and socioeconomic status of the population relies an area-based measure of socioeconomic status.This paper explores the reliability of the area of address (at the levels typically available in administrative data collections) as a proxy measure for socioeconomic disadvantage. The Western Australian Data Linkage System was used to show the extent to which hospital inpatient separation rates for residents of Perth vary by socioeconomic status of area of residence, when calculated at various levels of aggregation of area, from smallest (Census Collection District) to largest (postcode areas and Statistical Local Areas). Results are also provided of the reliability, over time, of the address as a measure of socioeconomic status. RESULTS: There is a strong association between the socioeconomic status of the usual address of hospital inpatients at the smallest level in Perth, and weaker associations when the data are aggregated to larger areas. The analysis also shows that a higher proportion of people from the most disadvantaged areas are admitted to hospital than from the most well-off areas (13% more), and that these areas have more separations overall (47% more), as a result of larger numbers of multiple admissions.Of people admitted to hospital more than once in a five year period, four out of five had not moved address by the time of their second episode. Of those who moved, the most movement was within, or between, areas of similar socioeconomic status, with people from the most well off areas being the least likely to have moved. CONCLUSION: Postcode level and SLA level data provide a reliable, although understated, indication of socioeconomic disadvantage of area. The majority of Perth residents admitted to hospital in Western Australia had the same address when admitted again within five years. Of those who moved address, the majority had moved within, or between, areas of similar socioeconomic status.Access to data about individuals from the Western Australian Data Linkage System shows that more people from disadvantaged areas are admitted to a hospital, and that they have more episodes of hospitalisation. Were data to be available across Australia on a similar basis, it would be possible to undertake research of greater policy-relevance than is currently possible with the existing separations-based national database.

Journal Article↗
PubMed2006

Exploiting the potential of routine data to better understand the disease burden posed by allergic disorders.

The Department of Health and Scottish Executive are currently undertaking independent reviews of allergy services in England (and Wales) and Scotland. Each review will assess the disease burden posed by allergic problems, involving secondary analyses of routine National Health Service (NHS) datasets. Major suggestions for re-structuring and/or re-focusing the NHS efforts to better deal with allergic disease are anticipated. The UK has some of the best datasets of routine health data in the world, but despite their strengths, they have important limitations. These include gaps in data collection, particularly in relation to monitoring of Accident & Emergency and out-patient consultations, and in-patient prescribing, thereby resulting in considerable under-estimates of hospital workload. The current gaps in service monitoring are likely to under-estimate the burden and workload associated with allergic problems, particularly in secondary care. One major limitation of existing data sources is the general inability to link individual patient level data between different datasets. By unlocking this potential there are very considerable potential gains to be made. Data linkage techniques currently being developed in the UK offer exciting new possibilities of looking across the primary-, secondary- and tertiary-care interfaces and also assessing short-and long-term social and educational outcomes in relation to allergic disorders. The current reviews of allergy services being undertaken need to be cognisant of these inherent limitations of existing data sources and would do well to recommend strategic initiatives that could enhance the availability, accessibility and quality of these datasets. Ideally, this should include investment in central data repositories staffed by teams with the necessary technical and statistical expertise, which would also take responsibility for progressing data linkage capabilities.

Drug Prescriptions↗
PubMed1988

Use of linkage disequilibrium data in prenatal diagnosis of cystic fibrosis.

Parents at risk of bearing a child with cystic fibrosis, and who have no living affected child, often use prenatal diagnosis based on microvillar enzyme assay in second-trimester amniotic fluid samples. If enzyme levels are abnormal and the pregnancy is terminated, it is possible in principle to use the fetal tissues to establish the phase relationship of linked DNA markers for a subsequent first-trimester prenatal diagnosis. However, the probability of a fetus being affected after an abnormal microvillar enzyme test may be no greater than 80%. The strong linkage disequilibrium between haplotypes at the D7S23 locus and the cystic fibrosis gene may be used to increase this probability. If fetal tissues are homozygous for the 6.6-kb band defined by pKM.19 and PstI and also homozygous for the 2.1-kb band with pXV-2c and TaqI, the chance of being affected increases from 80% to between 95% and 97%. We regard this as being sufficiently certain for use in phase determination.

Cystic Fibrosis↗