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PubMed2005

[Three sisters of pulmonary Mycobacterium avium complex disease].

We reported three sisters of pulmonary Mycobacterium avium complex (MAC) disease. The oldest sister was complaining of bloody sputum, and cultures were positive for M. avium. By monotherapy with clarithromycin, symptom and imaging findings had shown no progression for six years. The second sister was complaining of productive cough, and cultures were positive for M. intracellulare. Her symptom and imaging findings had shown no progression for seven years without any treatment. The third sister had rheumatoid arthritis and diabetes mellitus, and cultures were positive for M. intracellulare. Although she received chemotherapy with rifampicin, clarithromycin, ethambutol, and kanamycin, symptom and imaging findings had progressed gradually. She died of respiratory failure four years later. Autopsy findings revealed no disseminated MAC disease. The results which three cases showed different isolate patterns and clinical courses suggest the importance of underlying anti-mycobacterial immunological impairment and defects of local host defense rather than virulence of infected strains as the pathogenesis of pulmonary MAC disease.

Aged↗

PubMed1998

Linkage disequilibrium mapping of complex disease: fantasy or reality?

In the past year, data about the level and nature of linkage disequilibrium between alleles of tightly linked SNPs have started to become available. Furthermore, increasing evidence of allelic heterogeneity at the loci predisposing to complex disease has been observed, which has lead to initial attempts to develop methods of linkage disequilibrium detection allowing for this difficulty. It has also become more obvious that we will need to think carefully about the types of populations we need to analyze in an attempt to identify these elusive genes, and it is becoming clear that we need to carefully re-evaluate the prognosis of the current paradigm with regard to its robustness to the types of problems that are likely to exist.

Chromosome Mapping↗

PubMed1998

The power to detect linkage in complex disease by means of simple LOD-score analyses.

Maximum-likelihood analysis (via LOD score) provides the most powerful method for finding linkage when the mode of inheritance (MOI) is known. However, because one must assume an MOI, the application of LOD-score analysis to complex disease has been questioned. Although it is known that one can legitimately maximize the maximum LOD score with respect to genetic parameters, this approach raises three concerns: (1) multiple testing, (2) effect on power to detect linkage, and (3) adequacy of the approximate MOI for the true MOI. We evaluated the power of LOD scores to detect linkage when the true MOI was complex but a LOD score analysis assumed simple models. We simulated data from 14 different genetic models, including dominant and recessive at high (80%) and low (20%) penetrances, intermediate models, and several additive two-locus models. We calculated LOD scores by assuming two simple models, dominant and recessive, each with 50% penetrance, then took the higher of the two LOD scores as the raw test statistic and corrected for multiple tests. We call this test statistic "MMLS-C." We found that the ELODs for MMLS-C are >=80% of the ELOD under the true model when the ELOD for the true model is >=3. Similarly, the power to reach a given LOD score was usually >=80% that of the true model, when the power under the true model was >=60%. These results underscore that a critical factor in LOD-score analysis is the MOI at the linked locus, not that of the disease or trait per se. Thus, a limited set of simple genetic models in LOD-score analysis can work well in testing for linkage.

Chromosome Mapping↗

PubMed2006

Metabolomic approaches to phenotype characterization and applications to complex diseases.

Metabolites are the key regulators of systems homeostasis. As such, concentration changes of specific groups of metabolites may reflect systemic responses to environmental, therapeutic or genetic interventions. Thus, the study of metabolites is a powerful tool for the characterization of complex phenotypes as well as for the development of biomarkers for specific physiological responses. Therefore, metabolomics is a valuable platform for studies of complex diseases and the development of new therapies, both in nonclinical disease model characterization and clinical settings.

Animals↗

PubMed1990

Bell's palsy: an immune complex disease.

Serum levels of C4-containing circulating immune complexes in 48 patients with Bell's palsy were studied by an enzyme-linked immunosorbent assay (ELISA) using chicken antibodies. We have previously reported elevated levels of C1q- and C3-containing immune complexes when compared to the serum of 42 healthy persons. We now found the levels of C4-containing immune complexes in these sera to be slightly decreased, but these patients' sera had a slightly increased ability to activate and bind C4 to a model immune complex. The results indicate that the fairly low levels of C4-containing immune complexes were not due to a defect in C4 activation but point to a rapid modification of C4 in the immune complex in vivo or low binding of C4 to the immune complexes. This study also shows that it is preferable to use assays that detect C1q- and C3-containing immune complexes when analyzing sera from patients with Bell's palsy.

Adult↗

PubMed2003

Genetic variation at the chromosome 16 chemokine gene cluster: development of a strategy for association studies in complex disease.

The chemokine gene cluster [CCL22, CX3CL1, CCL17] (previously known as [SCYA22, SCYD1, SCYA17]) is a candidate locus for one of the susceptibility genes for inflammatory bowel disease that are located in the peri-centromeric region of chromosome 16. Screening for sequence variation at this locus led to the detection of 14 single nucleotide polymorphisms (SNPs). An efficient experimental and computational approach was developed to estimate allele frequencies and pairwise linkage disequilibrium relationships between SNPs at this locus, and to test them for association with inflammatory bowel disease. The 12 common SNPs were assigned to 5 distinct linkage disequilibrium groups. Genotyping of one SNP from each linkage disequilibrium group in a large cohort of families with inflammatory bowel disease did not provide convincing evidence of association with either Crohn's disease or ulcerative colitis. We describe an efficient experimental design from SNP screening to association testing. This strategy can be used to test candidate genes for involvement in susceptibility to complex disease.

Chemokines↗

PubMed2005

Genomic epidemiology of complex disease: the need for an electronic evidence-based approach to research synthesis.

Modern microarray genotyping now permits simultaneous analysis of tens of thousands of polymorphisms, and this technology is being widely used to associate the role of genes with the etiology of complex disease. Genome-wide hypothesis-free mapping will also increasingly generate candidate genes that require further testing in association studies. At the same time, genetic effects are increasingly observed to be buffered by a wide array of biologic mechanisms that evolved to protect the genome from environmental insult and that serve to obscure observation of direct effects of polymorphisms on a disease phenotype. These two forces combine to make replication of genomic epidemiology extraordinarily difficult. Traditional research synthesis of emerging bodies of genomic epidemiology is problematic and often quickly outdated. The author proposes that electronic evidence-based methodology, perhaps modeled after that used by the Cochrane Collaboration in clinical medicine, would facilitate the systematic preparation and frequent updating of systematic reviews, which is essential for identifying valid and replicable gene-disease associations.

Chromosome Mapping↗

PubMed1976

Acute immune complex disease associated with hepatitis. Etiopathogenic and immunopathologic studies of the renal lesion.

Immune deposit glomerulonephritis has been associated with hepatitis B antigenemia. Immune complexes of this antigen and its antibody have been implicated in the pathogenesis of the renal disease. A boy had acute immune complex disease with glomerulitis in which cryoprecipitable complexes of HbsAg and its antibody were isolated from serum. HbsAg was concentrated in the cryoprecipitate and localized in a granular pattern along the glomerular basement membrane in association with immunoglobulins. Glomerular fixed antibody was eluted and shown to be directed against HbsAg. The level of antibody activity to HbsAg was higher in the eluate than the serum, suggesting immunopathogenic specificity of the antibody. The study demonstrates that the nephritis was mediated by immune complexes of HbsAg and its antibody, and the presence of immunoglobulin on the kidney did not represent trapping from the circulation.

Child↗

PubMed2000

[Mycobacterium avium complex disease in HIV seropositive patients: incidence and risk factors before and after the introduction of highly active antiretroviral treatments. Clinical Epidemiology Group of the Information and Care Center for Human Immunodeficiency].

The objective of this study was to determine the risk factors of the first occurrence of Mycobacterium avium complex disease (MAC) infection among human immunodeficiency virus (HIV)-infected subjects during two different time periods: before and after the introduction of protease inhibitor (respectively, period 1: 1 January 1992 to 31 December 1995, and period 2: 1 January 1996 to 30 June 1998). This study was performed using the French Hospital Database on HIV (FHDH). Subjects were included when their CD4+ cell count was less than 100/mm3. If they did not die or develop MAC within the first 6 months after the inclusion, their follow-up had to be longer than 6 months to be included. Cox's model was used to calculated the relative hazards (RH) of MAC occurrence according to the age and time-dependent variables, such as CD4+ below 50/mm3, previous occurrence of tuberculosis, cytomegalovirus (CMV) infection and other acquired immunodeficiency syndrome (AIDS)-defining disease, nature of antiretroviral treatment and MAC prophylaxis. Among the 14,779 subjects followed during period 1, 1,710 (11.6%) had a diagnosis of MAC infection during their follow-up (incidence: 8.4 +/- 0.2 for 100 persons per year), while only 453 (4.4%) among 10,239 subjects presented this infection during period 2 (2.8 +/- 0.1 for 100 persons per year). Rifabutin regular prescription was a protective factor of MAC occurrence during period 1 (RH = 0.51 95% confidence interval (CI) = [0.37-0.69]), whereas this protective effect was not observed during period 2 (RH = 1.05 CI = [0.63-1.67]). Thus, during the HAART period, the results that we present do not indicate an interest into continuing MAC prophylaxis.

Adult↗

PubMed2004

The law of mass action applied to neurodegenerative disease: a hypothesis concerning the etiology and pathogenesis of complex diseases.

Loci underlying autosomal dominant forms of most neurodegenerative disease have been identified: prion mutations cause Gerstmann Straussler syndrome and hereditary Creuzfeldt-Jakob disease, tau mutations cause autosomal dominant frontal temporal dementia, and alpha-synuclein mutations cause autosomal dominant Parkinson's disease. In all these cases, the pathogenic mutation is in the protein that is deposited in the diseased tissue and in these cases the whole protein is deposited. In Alzheimer's disease, mutations in APP or presenilin 1 or 2 cause autosomal dominant disease and these are the substrate and proteases, respectively, which are responsible for the production of the deposited peptide, Abeta. Thus, in all cases, the mutations lead to the disease by a mechanism that involves the deposition process. We briefly review this remarkably predictable biology, but also point out that it seems sporadic forms of all these diseases are predisposed to by genetic variability at the same loci, strongly suggesting that the quantity of the normal protein produced influences risk for the sporadic forms of the disease. The evidence for this assertion is strongest in Parkinson's disease (PD), where genetic variability in alpha-synuclein expression affects risk of developing disease, although the oldest evidence for the notion that increased expression of normal sequence protein can lead to disease comes from the observation of Alzheimer's disease in trisomy 21 cases. From these observations, we make predictions concerning the etiology and pathogenesis of neurodegenerative diseases in general.

Haplotypes↗

PubMed1980

Immune-complex disease in mice and humans given C. parvum.

The present studies in mice and cancer-bearing patients, treated with C. parvum (CP) immunotherapy, were to determine the effects of CP on the production of immune complexes (IC) and associated disease. Using the Clq-binding assay, circulating immune complexes were detected in mice given a single high dose of CP (466 microgram) and repeated human-equivalent doses (70 microgram). All mice treated with CP developed proliferative glomerulonephritis, the severity of which was dose-related. The histological and immunofluorescent patterns of the nephritis were those attributed to immune-complex disease. The mice had haematuria but were not in renal failure. Fifty patients with inoperable lung cancer were studied. All received radiotherapy. Twenty-two had no other treatment (controls) and 28 were treated with infusions of CP. Using 2 immune-complex assays (Clq binding and monoclonal rheumatoid-factor binding) IC were found in 10/22 control patients but these did not develop haematuria or proteinuria. Twenty-four of the 28 patients treated with CP developed transient haematuria and/or proteinuria with red-cell and hyaline casts, the changes resolving over 5 days. Immune complexes were detected in 5 of these 28 patients before CP treatment. Although 16/28 had IC at the time of haematuria and proteinuria, these findings were difficult to interpret because IC may occur in response to the tumour, the radiotherapy, or the CP. Although no patient developed renal failure, we believe that those treated with CP should have regular assessment of their renal function.

Adult↗

PubMed2006

Assessing risk assessment: genetic testing and screening for complex disease.

This paper reports on the presentations from the second session of a 2-day workshop on genetic diversity and science communication, organized by the Institute of Genetics. The four talks in this session (by Sarah Cunningham-Burley, Gail Geller, Michael Hayden, and Theresa Marteau) focused on the topic of risk assessment in the context of genetic testing, screening and preventive medicine for complex disease. Each talk underscored the urgency and importance of evaluating when and for whom risk assessment may be useful. A recurrent theme was the need to attend closely to the diverse ways that risk is constructed, perceived and communicated in a variety of contexts and the significant implications of this for laypersons as well as experts. Although there was no consensus on when genetic risk assessment ceases (or might begin) to be useful, ensuing dialogue between presenters and participants reflected what is perhaps a new and critical engagement with how risk assessment itself is assessed. In response to this impetus, I use the word RISK as a heuristic to identify, extract and amplify four tendencies that appear to advance understandings of risk assessment towards a more explicitly reflexive, interpretive, and situated form of knowing.

Communication↗

PubMed2005

Studies on the management of root-knot nematode, Meloidogyne incognita-wilt fungus, Fusarium oxysporum disease complex of green gram, Vigna radiata cv ML-1108.

Studies were conducted under pot conditions to determine the comparative efficacy of carbofuran at 1 mg a.i./kg soil, bavistin at 1 mg a.i./kg soil, neem (Azadirachta indica) seed powder at 50 mg/kg soil, green mould (Trichoderma harzianum) at 50.0 ml/kg soil, rhizobacteria (Pseudomonas fluorescens) at 50.0 ml/kg soil against root-knot nematode, Meloidogyne incognita-wilt fungus, Fusarium oxysporum disease complex on green gram, Vigna radiata cv ML-1108. All the treatments significantly improved the growth of the plants as compared to untreated inoculated plants. Analysis of data showed that carbofuran and A. indica seed powder increased plant growth and yield significantly more in comparison to bavistin and P. fluorescens. Carbofuran was highly effective against nematode, bavistin against fungus, A. indica seed powder against both the pathogens and both the bioagents were moderately effective against both the pathogens.

Animals↗

PubMed1992

Absence of Mycobacterium avium complex disease in patients with AIDS in Uganda.

The absence of disease due to Mycobacterium avium in Ugandan patients with AIDS, which we previously observed in a blood culture study, has been confirmed and our observations have been extended to 165 additional clinical isolates. Fourteen soil and water samples from the Ugandan environment have been cultured and revealed a high frequency of isolation of M. avium. The absence of M. avium complex disease in Uganda remains unexplained.

Acquired Immunodeficiency Syndrome↗

PubMed2004

Colorectal cancer as a complex disease: defining at-risk subjects in the general population - a preventive strategy.

Over the last few decades it has become clear that highly penetrant disease genes are responsible for a minor proportion of colorectal cancer cases. Families with hereditary syndromes are today recognized and included in surveillance programs known to reduce morbidity and mortality in colorectal cancer. Colorectal cancer is preventable and screening strategies in whole populations are currently under debate. Colorectal cancer can be considered a complex disease, with a combination of predisposing genetic variants and environmental factors that contribute to the illness as a whole. The progress made in the genome project provides an opportunity to determine such genetic variants and environmental factors. This knowledge can be used to define a subpopulation at increased risk for colorectal cancer. It will be more feasible to design preventive strategies for this subgroup than for a whole population.

Animals↗

PubMed2003

Genome association studies of complex diseases by case-control designs.

One way to perform linkage-disequilibrium (LD) mapping of genetic traits is to use single markers. Since dense marker maps-such as single-nucleotide polymorphism and high-resolution microsatellite maps-are available, it is natural and practical to generalize single-marker LD mapping to high-resolution haplotype or multiple-marker LD mapping. This article investigates high-resolution LD-mapping methods, for complex diseases, based on haplotype maps or microsatellite marker maps. The objective is to explore test statistics that combine information from haplotype blocks or multiple markers. Based on two coding methods, genotype coding and haplotype coding, Hotelling's T2 statistics TG and TH are proposed to test the association between a disease locus and two haplotype blocks or two markers. The validity of the two T2 statistics is proved by theoretical calculations. A statistic TC, an extension of the traditional chi2 method of comparing haplotype frequencies, is introduced by simply adding the chi2 test statistics of the two haplotype blocks together. The merit of the three methods is explored by calculation and comparison of power and of type I errors. In the presence of LD between the two blocks, the type I error of TC is higher than that of TH and TG, since TC ignores the correlation between the two blocks. For each of the three statistics, the power of using two haplotype blocks is higher than that of using only one haplotype block. By power comparison, we notice that TC has higher power than that of TH, and TH has higher power than that of TG. In the absence of LD between the two blocks, the power of TC is similar to that of TH and higher than that of TG. Hence, we advocate use of TH in the data analysis. In the presence of LD between the two blocks, TH takes into account the correlation between the two haplotype blocks and has a lower type I error and higher power than TG. Besides, the feasibility of the methods is shown by sample-size calculation.

Case-Control Studies↗

PubMed2003

Multilocus statistics to uncover epistasis and heterogeneity in complex diseases: revisiting a set of multiple sclerosis data.

New statistics are developed to gather the contribution of many alleles at different loci to common diseases. Both inferential and descriptive statistics are included in order to uncover epistatic effects as well as heterogeneity. The problem of multiple testing is circumvented by considering a global null hypothesis. Global testing is supplemented by descriptive methods that make use of measures like odds ratio or the P-value of individually tested allele combinations. Visualization helps to reflect complex data sets. The methods described here have been scrutinized by statistical simulations, and we show that power gains can be substantial as compared to single locus statistics. Typing data of multiple sclerosis patients and controls are investigated, representing an example of larger scale information in screening candidate genes for their impact on complex diseases. New insights emerge from this data set demonstrating genetic heterogeneity and evidence for epistasis.

Adult↗

PubMed2001

Comparison of likelihood approaches for combined segregation and linkage analysis of a complex disease and a candidate gene marker under different ascertainment schemes.

We compared two joint likelihood approaches, with complete (L1) or without (L2) linkage disequilibrium, under different ascertainment schemes, for the genetic analysis of the disease trait and marker gene 1 in replicate 42. Joint likelihoods were computed without a correction for the selection scheme. For the different sampling schemes we have explored, our results suggest that L1 is a more powerful approach than L2 to detect major gene and covariate effects as well as to identify accurately gene x covariate interaction effects in a common and complex disease such as the Genetic Analysis Workshop 12 MG6 simulated trait.

Adult↗