Biomedical subjects

Kent D Taylor

Publications and source records attributed to Kent D Taylor.

44 records · Page 3Linked to original sources

PubMed2005

Association of the diabetes gene calpain-10 with subclinical atherosclerosis: the Mexican-American Coronary Artery Disease Study.

The powerful relation between atherosclerosis and diabetes may have a common genetic basis. However, few genes predisposing to both have been identified. Calpain-10 (CAPN10) was the first gene for type 2 diabetes identified by positional cloning, wherein a combination of haplotypes conferred increased risk of diabetes. We sought to determine whether CAPN10 influences subclinical atherosclerosis. Among nondiabetic subjects from 85 Mexican-American families with a history of coronary artery disease, subclinical atherosclerosis was assessed by common carotid artery intima-media thickness (IMT), insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamp, and insulin secretion was estimated by the oral glucose tolerance test. These phenotypes were tested for association with CAPN10 haplotypes. Haplotype 1112 (of single nucleotide polymorphisms [SNPs] 44, 43, 56, and 63) was associated with increased IMT, while haplotype 1221 was associated with decreased IMT. The 112/121 haplotype combination (of SNPs 43, 56, and 63), originally found to confer increased risk for diabetes, was associated with the largest IMT in our study population. CAPN10 was also associated with both insulin sensitivity and insulin secretion. Covariate analysis suggested that CAPN10 affects IMT independently of these diabetes-related phenotypes. The fact that the diabetes gene CAPN10 also influences the risk for atherosclerosis shows that inherited factors may underlie the frequent co-occurrence of these two conditions.

Adolescent↗

PubMed2004

Association of antibody responses to microbial antigens and complications of small bowel Crohn's disease.

BACKGROUND & AIMS: Crohn's disease patients can be characterized by antibody responses against Crohn's disease-related bacterial sequence, Escherichia coli outer membrane porin C, Saccharomyces cerevisiae (oligomannan), and neutrophil nuclear antigens. Our aim was to determine whether expression of antibodies against Crohn's disease-related bacterial sequence and Escherichia coli outer membrane porin C is associated with distinct phenotypic manifestations. METHODS: Sera from 303 patients were tested for antibodies to the Crohn's disease-related bacterial sequence (I2), anti-Escherichia coli outer membrane porin C, anti-Saccharomyces cerevisiae, and perinuclear antineutrophil cytoplasmic antibodies and for 3 Crohn's disease-associated variants of the NOD2 gene (R702W, G908R, and 1007fs) and compared with clinical data. RESULTS: Patients expressing I2 were more likely to have fibrostenosing Crohn's disease (64.4% vs. 40.7%; P < 0.001) and to require small bowel surgery (62.2% vs. 37.4%; P < 0.001). Patients with anti-Escherichia coli outer membrane porin C were more likely to have internal perforating disease (50.0% vs. 30.7%; P = 0.001) and to require small bowel surgery (61.4% vs. 44.2%; P = 0.003). Anti-Crohn's disease-related bacterial sequence was independently associated with fibrostenosis (P = 0.027) and small bowel surgery (P = 0.01), whereas anti-Escherichia coli outer membrane porin C was independently associated with internal perforations (P < 0.006). Patients positive for I2, anti-Escherichia coli outer membrane porin C, and anti-Saccharomyces cerevisiae were the most likely to have undergone small bowel surgery (72.0%; odds ratio, 8.6; P < 0.001) compared with patients without reactivity (23.0%). When the presence and magnitude of antibody responses were considered, 90% of patients with small bowel disease who required surgery had high levels of I2, Escherichia coli outer membrane porin C, and oligomannan antibodies, compared with only 18.2% with low-titer responses (P < 0.001). CONCLUSIONS: I2 and anti-Escherichia coli outer membrane porin C are associated with Crohn's disease phenotypes, and patients with the highest level of serum reactivity toward an increasing number of microbiota have the greatest frequency of strictures, internal perforations, and small bowel surgery.

Adult↗

PubMed2004

Lipoprotein lipase is a gene for insulin resistance in Mexican Americans.

The insulin resistance syndrome is increasingly recognized as a risk factor for cardiovascular disease. Lipoprotein lipase (LPL) is a candidate gene for components of the syndrome. A small number of studies have demonstrated association of single nucleotide polymorphisms within LPL and indirect or surrogate measures of insulin resistance, largely based on glucose and insulin values obtained in the fasting state or during an oral glucose tolerance test. To test directly whether LPL is an insulin resistance gene, we performed the hyperinsulinemic-euglycemic clamp in a large family-based population of Mexican Americans who were genotyped at six polymorphisms in LPL that define the most common haplotypes in the population. LPL haplotypes showed linkage to the glucose infusion rate (GINF), a direct physiologic measurement of insulin sensitivity (P = 0.034). In addition, significant associations with GINF were demonstrated for the most common haplotype (P = 0.031) and the fourth most common haplotype (P = 0.007). Haplotype 1 was associated with insulin sensitivity (mean GINF for haplotype 1 carriers = 383.0 mg/min) and haplotype 4 with insulin resistance (mean GINF for haplotype 4 carriers = 344.3 mg/min). This haplotype-based genetic analysis provides compelling evidence that variation in the LPL gene plays a role in determining insulin resistance in this ethnic group with a high prevalence of the insulin resistance syndrome.

Adult↗

PubMed2003

A novel NOD2/CARD15 haplotype conferring risk for Crohn disease in Ashkenazi Jews.

Crohn disease (CD) exhibits a 2-4-fold increased frequency in Jews as compared with other ethnic/racial groups. Three coding variants of the NOD2/CARD15 have been reported as independent disease-predisposing mutations (DPMs), but these were found in only 30%-40% of patients with CD and could not account for all the linkage between CD and the IBD1 locus. The aim of the present study was to explore whether additional DPMs at the IBD1 locus exist in the high-risk Jewish group. Sixty-four Ashkenazi Jewish and 147 non-Jewish white families were studied. Six microsatellite markers spanning IBD1 were genotyped for linkage analysis in subgroups stratified on NOD2/CARD15 DPM status. SNPs in NOD2/CARD15 (R702W, G908R, 1007fs, and S268P) were then genotyped in family and independent case-control samples. On the basis of initial results, sequencing was done on NOD2/CARD15-translated regions in 12 Jewish individuals. Subsequently, a new NOD2/CARD15 variant was genotyped and analyzed. After excluding the influence of the three DPMs, significant linkage of IBD1 to CD in Jews remained with two peaks at D16S403 (mean allele sharing [MAS] = 0.70] and D16S411 (MAS = 0.59). Further, we observed an increased frequency of a haplotype carrying only the 268S variant in Jewish patients (OR = 3.13, P=.0023) but not in non-Jews, suggesting the existence of a Jewish-specific additional disease-predisposing factor on this haplotype. Sequencing of this haplotype revealed a new variant (IVS8+158; JW1). The 268S-JW1 combination exhibited a further increased risk (OR = 5.75, P=.0005) and the highest population-attributable risk (15.1%) for CD among reported DPMs in Jews. In Ashkenazi Jews, unrecognized population-specific predisposing factor(s) exist on the 268S-JW1 haplotype at the IBD1 locus. This factor may contribute to the higher risk for CD in Ashkenazi Jews as compared with non-Jews.

Amino Acid Substitution↗

PubMed2002

Mutations in NOD2 are associated with fibrostenosing disease in patients with Crohn's disease.

BACKGROUND & AIMS: The clinical manifestations of Crohn's disease (CD) are diverse, ranging from fibrostenosing small-bowel disease to colon-predominant inflammation. These distinctions may represent genetic, immunologic, and microbial heterogeneity. NOD2 gene mutations in CD have been described recently and may alter innate immune responses. We hypothesized that NOD2 mutations may be associated with distinct phenotypic expressions of CD. METHODS: Two cohorts of consecutively identified patients referred to an inflammatory bowel disease center (n = 142 collected between 1993 and 1996; n = 59 collected between 1999 and 2001) were genotyped for 3 single nucleotide variants of NOD2-R675W, G881R, and 3020insC-and phenotyped for disease behavior, disease location, and serum immune markers. RESULTS: Univariate analysis showed that CD-associated NOD2 variants were significantly associated with fibrostenosing disease in each cohort (P = 0.049 and P = 0.002, respectively). When both cohorts were analyzed together, the association between NOD2 variants and fibrostenosing disease was more significant (P = 0.001). These relationships were observed in both Jews and non-Jews. Forty-six percent of patients with fibrostenosing disease carried at least 1 of these alleles, compared with only 23.5% of patients without fibrostenosing disease (odds ratio, 2.8; 95% confidence interval, 1.6-5.2). Multivariate and conditioning analyses showed a primary association between NOD2 allelic variants and fibrostenosing disease, but not with small-bowel disease. CONCLUSIONS: In this description of a genotype/phenotype correlation in CD patients and NOD2 variants, data suggest that variation in this gene contributes to the occurrence of fibrostenotic CD of the small bowel.

Adolescent↗

PubMedDate not supplied

Determination and use of haplotypes: ethnic comparison and association of the lipoprotein lipase gene and coronary artery disease in Mexican-Americans.

PURPOSE: To illustrate an approach of deriving haplotypes for genetic association studies, using the lipoprotein lipase (LPL) gene and coronary artery disease. METHODS: Six polymorphisms sufficient to distinguish the most common haplotypes in the 3' end of LPL were identified by genotyping 10 polymorphisms in a small pilot population. These were used to haplotype LPL in large family samples of Mexican-Americans and non-Hispanic Caucasians. A case-control association study was performed comparing Mexican-Americans with and without coronary artery disease. RESULTS: The two ethnic groups exhibited significant genetic differences. Among Mexican-Americans, homozygosity for LPL haplotype 1 was protective against coronary artery disease (OR = 0.50, 95% CI 0.27-0.91). CONCLUSION: This study outlines the haplotype structure of the LPL gene, illustrates the utility of haplotype-based analysis in association studies, and demonstrates the importance of defining haplotype frequencies for different ethnic groups.

Alleles↗

PubMedDate not supplied

Lipoprotein lipase locus and progression of atherosclerosis in coronary-artery bypass grafts.

PURPOSE: Our aim was to test whether polymorphisms in the lipoprotein lipase (LPL) gene were associated with the progression of atherosclerosis in grafts examined in the Post-Coronary Artery Bypass Graft Trial (Post-CABG Trial). METHODS: 843 subjects in the post-CABG trial were genotyped for the LPL-D9N, N291S, PvuII, (TTTA)n, and HindIII polymorphisms. Associations between genotype and angiographically measured progression of atherosclerosis in grafts, medical history, and family history were examined. RESULTS: Greater progression of atherosclerosis was observed in subjects with LPL-HindIII 2/2 (56% versus 42% of those with other LPL HindIII genotypes, P = 0.025) and with LPL (TTTA)n 4/4 (63% versus 43% of those with other (TTTA)n genotypes, P = 0.020). Mantel-Haenszel analysis yielded an odds ratio of 1.84 for the effect of LPL HindIII 2/2 genotype on the progression of atherosclerosis in grafts (P = 0.015) and demonstrated that the effect of genotype on progression was of the same magnitude as, but independent of, the effect of drug treatment. CONCLUSION: The LPL-HindIII 2/2 genotype is a marker for genetic variation in the 3'-end of LPL that acts as an independent risk factor for the progression of atherosclerosis in grafts examined in the Post-CABG Trial.

Arteriosclerosis↗

PubMedDate not supplied

Genomewide linkage scan in a multigeneration Caucasian pedigree identifies a novel locus for keratoconus on chromosome 5q14.3-q21.1.

PURPOSE: Keratoconus is a corneal dystrophy with an incidence of 1 in 2000 and a leading cause for cornea transplantation in Western developed countries. Both clinical observations and segregation analyses suggest a major role for genes in its pathogenesis. It is genetically heterogeneous, most commonly sporadic, but inherited patterns with recessive or dominant modes have also been reported. We studied a four-generation autosomal-dominant pedigree to identify disease loci for keratoconus. METHODS: A two-stage genome-wide scan was applied to 27 family members. First linkage analysis was performed with 343 microsatellite markers along the 22 autosomal chromosomes at approximately 10 cM density. This was followed by fine mapping at approximately 2 cM density, in regions suggestive of linkage. Multipoint linkage analysis was performed using GeneHunter2. RESULTS: Evidence of suggestive linkage from the initial scan was observed at the 82 to 112 cM region of chromosome 5q14.1-q21.3 with a maximum lod score (LOD) of 3.48 (penetrance = 0.5). Fine mapping by testing an additional 11 microsatellite markers at 1 to 3 cM intervals revealed a narrower and higher peak (99-119 cM) with LOD 3.53. By analysis of the recombination of haplotypes, the putative locus of keratoconus was further narrowed to a 6 cM region (8.2 Mbp physical distance) between markers D5S2499 and D5S495. CONCLUSION: These results indicate a promising new locus for keratoconus in this pedigree. Because of the heterogeneous nature of keratoconus, this locus may be specific to familial autosomal-dominant keratoconus. Nevertheless, the identification of this locus may provide new insights into the pathogenesis of keratoconus.

Adult↗