Genetic variation near the hepatocyte nuclear factor-4 alpha gene predicts susceptibility to type 2 diabetes.

The Finland-United States Investigation Of NIDDM Genetics (FUSION) study aims to identify genetic variants that predispose to type 2 diabetes by studying affected sibling pair families from Finland. Chromosome 20 showed our strongest initial evidence for linkage. It currently has a maximum logarithm of odds (LOD) score of 2.48 at 70 cM in a set of 495 families. In this study, we searched for diabetes susceptibility variant(s) at 20q13 by genotyping single nucleotide polymorphism (SNP) markers in case and control DNA pools. Of 291 SNPs successfully typed in a 7.5-Mb interval, the strongest association confirmed by individual genotyping was with SNP rs2144908, located 1.3 kb downstream of the primary beta-cell promoter P2 of hepatocyte nuclear factor-4 alpha (HNF4A). This SNP showed association with diabetes disease status (odds ratio [OR] 1.33, 95% CI 1.06-1.65, P = 0.011) and with several diabetes-related traits. Most of the evidence for linkage at 20q13 could be attributed to the families carrying the risk allele. We subsequently found nine additional associated SNPs spanning a 64-kb region, including the P2 and P1 promoters and exons 1-3. Our results and the independent observation of association of SNPs near the P2 promoter with diabetes in a separate study population of Ashkenazi Jewish origin suggests that variant(s) located near or within HNF4A increases susceptibility to type 2 diabetes.

Sex differences and their impact on clinical outcome after percutaneous or surgical revascularisation: a report from the Arterial Revascularisation Therapies Study (ARTS).

AIMS: To determine whether women have an unfavorable outcome after coronary interventions compared with men, we evaluated patients undergoing revascularisation within the Arterial Revascularisation Therapies Study (ARTS). METHODS AND RESULTS: We evaluated 1205 patients (23% women) with multivessel disease randomised to percutaneous or surgical coronary revascularisation. The in-hospital results, and clinical outcome at five years were evaluated. Women were older, with a higher prevalence of hypertension, hypercholesterolaemia, family history for coronary artery disease (all p<0.001), diabetes mellitus (p=0.05) and stable angina (p<0.05) than men, but had a lower incidence of history of myocardial infarction or smoking (both p<0.001). More major bleeding complications, even after adjusting for baseline clinical characteristics (OR 29.4, 95% CI: 5.3-500, p<0.005) were observed in women following percutaneous coronary intervention. During clinical follow-up freedom from major adverse cardiac and cerebrovascular events was similar in men and women, regardless of treatment strategy. Men assigned to bypass surgery had a better quality of life, but women reported more frequently angina. CONCLUSION: The clinical outcome of women with multivessel disease undergoing coronary revascularisation was similar to that in men. However, women presented more bleeding complications before hospital discharge, and had less favourable assessment in specific domain of daily life at follow-up.

Identification of high frequency of Y chromosome deletions in patients with sex chromosome mosaicism and correlation with the clinical phenotype and Y-chromosome instability.

A mosaic karyotype consisting of a 45,X cell line and a second cell line containing a normal or an abnormal Y chromosome is relatively common and is associated with a wide spectrum of clinical phenotypes. The aim of this study was to investigate patients with such a mosaic karyotype for Y chromosome material loss and then study the possible association of the absence of these regions with the phenotype, diagnosis, and Y-chromosome instability. We studied 17 clinically well-characterized mosaic patients whose karyotype consisted of a 45,X cell line and a second cell line containing a normal or an abnormal Y chromosome. The presence of the Y chromosome centromere was verified by fluorescence in situ hybridization (FISH) and was then characterized by 44 Y-chromosome specific-sequence tagged site (STS) markers. This study identifies a high frequency of Yq chromosome deletions (47%). The deletions extend from interval 5 to 7 sharing a common deleted interval (6F), which overlaps with the azoospermia factor region (AZF) region. This study finds no association between Y-chromosome loci hosting genes other than SRY, and the phenotypic sex, the diagnosis, and the phenotype of the patients. Furthermore, this study shows a possible association of these deletions with Y-chromosome instability.

The impact of SNP density on fine-scale patterns of linkage disequilibrium.

Linkage disequilibrium (LD) is a measure of the degree of association between alleles in a population. The detection of disease-causing variants by association with neighbouring single nucleotide polymorphisms (SNPs) depends on the existence of strong LD between them. Previous studies have indicated that the extent of LD is highly variable in different chromosome regions and different populations, demonstrating the importance of genome-wide accurate measurement of LD at high resolution throughout the human genome. A uniform feature of these studies has been the inability to detect LD in regions of low marker density. To investigate the dependence of LD patterns on marker selection we performed a high-resolution study in African-American, Asian and UK Caucasian populations. We selected over 5000 SNPs with an average spacing of approximately 1 SNP per 2 kb after validating ca 12 000 SNPs derived from a dense SNP collection (1 SNP per 0.3 kb on average). Applications of different statistical methods of LD assessment highlight similar areas of high and low LD. However, at high resolution, features such as overall sequence coverage in LD blocks and block boundaries vary substantially with respect to marker density. Model-based linkage disequilibrium unit (LDU) maps appear robust to marker density and consistently influenced by marker allele frequency. The results suggest that very dense marker sets will be required to yield stable views of fine-scale LD in the human genome.