Biomedical subjects

D Schaid

Publications and source records attributed to D Schaid.

17 recordsLinked to original sources

PubMed2001

Genetic variation in the transforming growth factor beta1 gene in multiple sclerosis.

Transforming growth factor beta1 (TGFbeta1) is a Th2 cytokine encoded on chromosome 19q13, a region possibly linked to multiple sclerosis (MS). TGFbeta1 exerts favorable effects on experimental allergic encephalomyelitis. We performed a comprehensive search for genetic variants in this gene in 122 population-based sporadic cases of MS. We detected six variants, including three missense variants. We tested for association of the variants with susceptibility and course of MS and for linkage and transmission disequilibrium in a family series consisting of 395 samples in 59 pedigrees. Genetic variation in TGFB1 does not appear to contribute in a major way to susceptibility to MS.

Adult↗

PubMed2000

BRCA1 and BRCA2 have a limited role in familial prostate cancer.

Epidemiological studies have suggested that the breast cancer susceptibility genes, BRCA1 and BRCA2, may be involved in the development of prostate cancer. Several studies have screened prostate cancer populations for the presence of BRCA1 and BRCA2 mutations, with few mutations identified. In this study, 22 high-risk prostate cancer families (at least three cases of prostate cancer) were screened by conformation-sensitive gel electrophoresis (CSGE) for mutations in BRCA1 and BRCA2. To maximize the chance of finding mutations in these two genes, families were also selected for the presence of at least two cases of breast and/or ovarian cancer. We identified one previously reported BRCA2 missense mutation and two previously unreported BRCA2 intron polymorphisms. No BRCA1 or BRCA2 truncating mutations were detected. Thus, BRCA1 and BRCA2 appear to have a limited role in familial prostate cancer, and families with both prostate and breast cancer may result from mutations in other predisposition genes.

Aged↗

PubMed2000

A prospective trial of midwest breast cancer patients: a p53 gene mutation is the most important predictor of adverse outcome.

Several retrospective studies have suggested p53 gene mutation as an adverse prognostic indicator in breast cancer patients, based on a selective growth advantage of p53 mutant cancer cells and their presumed resistance to current adjuvant therapy regimens. A cohort of 90 Caucasian midwestern breast cancer patients was analyzed prospectively (60 months of follow-up) with a rigorous mutation detection methodology. The presence of a p53 gene mutation was the single most adverse prognostic indicator for recurrence (p = 0.0032) and death (p = 0.0001), and was associated with poor response to both adjuvant (p = 0.0001) and palliative (p = 0.006) therapy. Analysis of the p53 gene with appropriate mutation detection methodology markedly improves the prediction of early recurrence, treatment failure, and death in breast cancer patients.

Breast Neoplasms↗

PubMed1999

Applicability of the case-parent design in the etiological research of Type 1 diabetes in Chile and other genetically mixed populations.

In case-control studies, spurious associations between Human Leukocyte Antigen (HLA) alleles and Type 1 diabetes could arise as a result of population stratification, if there are ethnic differences between cases and non-related controls. The Chilean population has several unique features which make it ideal for the study of the effect of stratification by ethnicity on genetic epidemiological research. The incidence rates of Type 1 diabetes in Chilean Aboriginal populations are very low compared to Caucasian populations, while the frequency of the alleles in HLA loci also vary across ethnic groups. In order to avoid the confounding effect of ethnicity, one possible remedy would be the use of cases and their parents in place of non-related controls. The case-parent design offers an adequate framework for the study of the association between HLA polymorphisms and Type 1 diabetes in the Chilean population and can also be applicable to other genetically mixed populations especially in the Americas.

Adolescent↗

PubMed1998

The association between HLA class I alleles and measles vaccine-induced antibody response: evidence of a significant association.

While the Moraten strain measles vaccine is an excellent, safe, and immunogenic vaccine, vaccine failure occurs, presumably when an individual develops an inadequate immune response. In this study, we examined the association of HLA class I genes and measles vaccine-induced antibody levels. We found that the allele distribution of HLA-B alleles differed between non-responders and hyper-responders (p = 0.002). Several class I alleles were associated with non-response (HLA-B13, -B44, and -C5); whereas several other alleles were associated with hyper-response (HLA-B7 and -B51). In addition, non-responders were more likely to be HLA-B homozygous than normal responders (odds ratio 2.1), and more likely to be homozygous than hyper-responders (odds ratio 3.7, p = 0.031 Mantel-Haenzel for trend). Finally, we found evidence of an allele dose-response phenomenon for HLA-B7. We conclude that there are important associations between class I HLA genes and measles antibody levels following immunization.

Adolescent↗

PubMed1998

Evidence for a prostate cancer susceptibility locus on the X chromosome.

Over 200,000 new prostate cancer cases are diagnosed in the United States each year, accounting for more than 35% of all cancer cases affecting men, and resulting in 40,000 deaths annually. Attempts to characterize genes predisposing to prostate cancer have been hampered by a high phenocopy rate, the late age of onset of the disease and, in the absence of distinguishing clinical features, the inability to stratify patients into subgroups relative to suspected genetic locus heterogeneity. We previously performed a genome-wide search for hereditary prostate cancer (HPC) genes, finding evidence of a prostate cancer susceptibility locus on chromosome 1 (termed HPC1; ref. 2). Here we present evidence for the location of a second prostate cancer susceptibility gene, which by heterogeneity estimates accounts for approximately 16% of HPC cases. This HPC locus resides on the X chromosome (Xq27-28), a finding consistent with results of previous population-based studies suggesting an X-linked mode of HPC inheritance. Linkage to Xq27-28 was observed in a combined study population of 360 prostate cancer families collected at four independent sites in North America, Finland and Sweden. A maximum two-point lod score of 4.60 was observed at DXS1113, theta=0.26, in the combined data set. Parametric multipoint and non-parametric analyses provided results consistent with the two-point analysis. Significant evidence for genetic locus heterogeneity was observed, with similar estimates of the proportion of linked families in each separate family collection. Genetic mapping of the locus represents an important initial step in the identification of an X-linked gene implicated in the aetiology of HPC.

Adult↗

PubMed1998

Major histocompatibility complex class II alleles and the course and outcome of MS: a population-based study.

BACKGROUND: The major histocompatibility complex (MHC) has been consistently associated with susceptibility to MS and the course of several other human autoimmune diseases. A putative association between the course and severity of MS and the MHC remains controversial. METHODS: DR and DQ genotyping by either restriction fragment length polymorphism or sequence-specific PCR-based typing in 119 patients representing 73.4% of the population with MS evaluated in a cross-sectional disability survey and 100 healthy controls from Olmsted County, Minnesota. RESULTS: We found a positive association between MS susceptibility and the DR15-DQ6 and DR13-DQ7 haplotypes, and we found a negative association with the DR1-DQ5 haplotype. We found a trend to a positive association of primary progressive MS with DR4-DQ8 and DR1-DQ5 and an association of "bout onset" MS with DR17-DQ2. We did not find an association with disease severity, as defined by EDSS/duration. CONCLUSION: Lack of consistency between different studies may be due to regional variation in MS and limitations of power but likely indicate a minor effect of MHC class II genes on the course and severity of MS.

Adult↗

PubMed1997

Expansion of unusual CD4+ T cells in severe rheumatoid arthritis.

OBJECTIVE: The repertoire of T cells in patients with rheumatoid arthritis (RA) is characterized by clonal expansion of selected CD4+ T cells, which are autoreactive and lack the expression of the functionally important CD28 molecule. The goal of this study was to determine the contribution of these unusual lymphocytes to the disease process. METHODS: RA patients (n = 108) and normal controls (n = 53) were examined for the expression of CD4+ CD28- T cells by 2-color fluorescence-activated cell sorter analysis. Clinical data were ascertained by retrospective chart review. RESULTS: The frequencies of CD4+ CD28- T cells displayed a bimodal distribution, defining carriers and noncarriers in normal subjects and RA patients. In longitudinal studies, the noncarrier and carrier phenotypes were stable over time. Carriers of CD4+ CD28- T cells accumulated in the RA population (64% versus 45%; P = 0.02). The expansion of CD4+ CD28- T cells correlated with extraarticular involvement, but not with disease duration, antirheumatic treatment, or severity of joint destruction. The patient subsets with nodular disease (P = 0.02) and rheumatoid organ disease (P = 0.04) had the highest proportion of CD4+ CD28- T cell carriers. The size of the CD4+ CD28- compartment correlated with extraarticular progression of RA (P = 0.001 in nodular RA, P = 0.003 in rheumatoid organ disease). CONCLUSION: The bimodality of distribution of CD4+ CD28- T cell frequencies is compatible with genetic control of the generation of these unusual T cells. In RA patients, CD4+ CD28- T cells are not an epiphenomenon of the disease process, but predispose patients to developing inflammatory lesions in extraarticular tissues.

Adult↗

PubMed1997

Age-Related Disease Penetrance in a Large Medullary Thyroid Cancer Family With a Codon 609 RET Gene Mutation.

Background: Familial medullary thyroid cancer (MTC) is a form of type 2 multiple endocrine neoplasia in which individuals develop MTC as the sole phenotypic manifestation of their disease. A previous study has suggested that patients with familial MTC may have a later age of onset (and more indolent course) of MTC than is observed in individuals with multiple endocrine neoplasia type 2A. Methods and Results: The age-related penetrance of MRC, C-cell hyperlasia, and a positive pentagastrin test for carriers of a codon 609 mutation of the RET gene in a large MTC family was determined. Pentagastrin testing and surgical pathology findings for patients who had thyroidectomies were correlated with RET sequence analysis findings. The penetrance of this mutation for the development of MTC was 0% at age 20, 10% at age 20, 10% at age 30, 50% at age 45, and approximately 100% at age 60. The ages of onset of C-cell hyperplasia and a positive pentagastrin stimulation test were similar, and both preceded the age of onset of MTC. Carriers of the mutated gene in this family had a later age of onset of disease that has been reported for families with multiple endocrine neoplasia type 2A and 2B syndromes. Conclusions: These results may have implications for the clinical management of MTC families with a 609 mutation.

Journal Article↗

PubMed1996

Mutation detection by highly sensitive methods indicates that p53 gene mutations in breast cancer can have important prognostic value.

Human cancer cells with a mutated p53 tumor-suppressor gene have a selective growth advantage and may exhibit resistance to ionizing radiation and certain chemotherapeutic agents. To examine the prognostic value of mutations in the p53 gene, a cohort of 90 Midwestern Caucasian breast cancer patients were analyzed with methodology that detects virtually 100% of all mutations. The presence of a p53 gene mutation was by far the single most predictive indicator for recurrence and death (relative risks of 4.7 and 23.2, respectively). Direct detection of p53 mutations had substantially greater prognostic value than immunohistochemical detection of p53 overexpression. Analysis of p53 gene mutations may permit identification of a subset of breast cancer patients who, despite lack of conventional indicators of poor prognosis, are at high risk of early recurrence and death.

Alternative Splicing↗

PubMed1995

Frequency of familial dilated cardiomyopathy.

Based on evaluation of 59 probands and their families, we previously demonstrated that over 20% of patients with idiopathic dilated cardiomyopathy (DCM) have familial disease. We acquired 36 additional probands and found familial disease in 24.2% of the 95 probands in this expanded consecutively ascertained cohort. The family history, as reported by the patient and relatives, is often an unreliable indicator of familial disease because patients may be unaware of the significance of a family history of sudden death, arrhythmia or stroke. We demonstrate that careful family history with review of medical records identifies more familial cases than merely asking the patient if there is a family history of DCM. However, even such a careful family history does not identify all familial cases. Some familial cases are identified only by echocardiographic investigation of asymptomatic relatives. We found no clinical attributes of probands, other than family history, which predicted familial disease.

Adolescent↗

PubMed1994

Novel pattern of p53 gene mutations in an American black cohort with high mortality from breast cancer.

The pattern of acquired mutations in the p53 gene can be used to study differences in factors contributing to carcinogenesis. We investigated mutations in exons 5-9 and adjacent intronic regions in 47 breast cancers of black women from Michigan, a population with the highest breast-cancer mortality in the US. The 16 mutations detected differed from those of other populations. In particular, the black women had an excess of A:T-->G:C transitions compared with rural white US midwest women. While the causes of the different pattern of acquired mutation remain to be determined, this molecular epidemiological approach detects the consequences of mutagenic processes in specific populations. Mutation patterns will constrain hypotheses to mechanisms consistent with the observed biochemical alterations.

Base Sequence↗

PubMed1994

p53 gene mutations in breast cancers in midwestern US women: null as well as missense-type mutations are associated with poor prognosis.

We determined the pattern of mutations in exons 2-11 and adjacent intronic regions in breast cancers from Midwestern US white women. Twenty-one mutations were detected in 53 tumors (39.6%). Comparisons of the pattern of mutations within exons 5-9 showed that the frequency of missense mutations (44%) was lower in breast cancers of US Midwestern women than in most tumor types including breast cancers in other populations. Compared to breast cancers reported in a Scottish population, US women had a high frequency of G:C-->T:A transversions (P = 0.046). These findings suggest that environmental or endogenous factors contribute to p53 mutagenesis in mammary tissue to different extents among different populations. With a median follow-up of 19 months, the presence of a mutation was associated with shorter time to disease recurrence (P = 0.05) and shorter survival (P = 0.003). Putative dominant negative missense-type mutations (missense and in-frame microdeletions; P = 0.001) and null mutations (hemizygous nonsense and frameshift mutations; P = 0.007) were equally ominous. Thus, tumors with missense p53 mutations resulting in over-expression of a dysfunctional but otherwise intact protein have a clinical outcome similar to tumors with null mutations resulting in a truncated or garbled protein.

Adult↗

PubMed1993

Microsatellite instability in cancer of the proximal colon.

Colorectal tumor DNA was examined for somatic instability at (CA)n repeats on human chromosomes 5q, 15q, 17p, and 18q. Differences between tumor and normal DNA were detected in 25 of the 90 (28 percent) tumors examined. This instability appeared as either a substantial change in repeat length (often heterogeneous in nature) or a minor change (typically two base pairs). Microsatellite instability was significantly correlated with the tumor's location in the proximal colon (P = 0.003), with increased patient survival (P = 0.02), and, inversely, with loss of heterozygosity for chromosomes 5q, 17p, and 18q. These data suggest that some colorectal cancers may arise through a mechanism that does not necessarily involve loss of heterozygosity.

Adult↗

PubMed1989

Genetic and physical mapping of a novel region close to the fragile X site on the human X chromosome.

We report the isolation and characterization of a novel DNA marker (1A1) in Xqter in the region of the fragile X. Genetic studies in families segregating for the fragile X syndrome suggest that 1A1 lies between the disease mutation and the distal locus, DXS52. Studies in normal and fragile X families show that 1A1 is tightly linked to DXS52 (Zmax = 17.20; theta max = 0.03) and F8 (Zmax = 7.01; theta max = 0.08). Multipoint mapping of families supports the order Xcen-DXS105-FRAXA-1A1-DXS52-(F8, DXS115)-Xqter. Pulsed-field gel electrophoresis (PFGE) studies demonstrate that 1A1 defines a new region of at least 2 Mb of DNA not physically linked to DXS52 or F8, thus extending the physical map of Xq27-qter to over 4 Mb. Complex partial digestion PFGE patterns, probably due to differing degrees of methylation, are observed with 1A1 in unrelated normal and fragile-X-positive individuals, whereas other distal markers give uniform digestion profiles. Physical data suggest that 1A1 lies in a region less CpG rich than other distal markers in Xq27-qter.

Animals↗

PubMed1989

An intronic region within the human factor VIII gene is duplicated within Xq28 and is homologous to the polymorphic locus DXS115 (767).

The genomic sequences recognized by the anonymous probe 767 (DXS115) are localized to two sites within Xq28. One site lies within intron 22 of the factor VIII gene (FBC). Physical mapping suggests that the second site lies within 1.2 megabases of the F8C gene. The RFLPs detected by 767 are located within the second site. Genetic data suggest that F8C and DXS115 are tightly linked (theta max = .04; Zmax = 8.30). Recombination events in meioses informative for DXS52 (St14), DXS115, and F8C suggest that DXS115 and F8C lie distal to DXS52.

Chromosome Deletion↗

PubMedDate not supplied

Androgen stimulation and laryngeal development.

Androgen-induced changes in laryngeal growth patterns were studied using a sheep animal model. Forty-eight lambs were divided into eight treatment groups. Lambs in seven of the groups were castrated at birth, while lambs in the eighth group served as an intact (noncastrated) control. Six groups were then treated with varying doses of testosterone and dihydrotestosterone, while the seventh served as a castrated, nontreated control. All animals were killed and gross dissections of the larynges were performed. Thirty-four linear and angular measurements were obtained from each larynx. The mean superior thyroid horn separation showed the most dramatic androgen-induced effect (p = 0.023). Laryngeal anterior-posterior diameter, superior thyroid horn height, posterior thyroid cartilage width, thyroid cartilage angle, and vocal process to arytenoid base distances all demonstrated positive dose-response relationships. Hypoandrogenic levels appeared to have an inhibitory effect upon laryngeal growth when compared to castrated controls.

Androgens↗