MICA marks additional risk factors for Type 1 diabetes on extended HLA haplotypes: an association and meta-analysis

The association of the HLA complex on chromosome 6 does not explain total linkage of the HLA region to Type 1 Diabetes (T1D), leading to the hypothesis that there may be additional causal genes in the HLA region for immune-related disorders. Reports on the MHC Class I chain-related A (MICA) gene as candidate for association with T1D are contradicting. We investigated whether variation in MICA is associated to T1D in a cohort of 350 unrelated individuals with juvenile-onset T1D and 540 control subjects, followed by a meta-analysis of 14 studies. We also investigated an HLA-independent association for MICA with T1D. In our case-control study, we found that the MICA*A5 variant was significantly associated with an increased risk for T1D, while MICA*A6 was significantly associated with a decreased risk that was confirmed by our meta-analysis. However, the meta-analysis did not show an association of MICA*A5 T1D. Analysis of MICA alleles conditional on T1D-associated high-risk MHC class II haplotypes revealed that MICA*A6 was associated with an increased risk for T1D when this marker co-occurred with HLA DQ2DR17 T1D-risk-haplotypes. In contrast, MICA*A6 reduced the risk from the HLA DQ8DR4 T1D-risk haplotype. Moreover, MICA*A9 showed a significant association to increased risk for T1D on DQ8DR4 haplotypes. Co-inheritance of MICA*A6 with the HLA DQ2DR17 haplotype in T1D indicates this haplotype may carry the additional genetic factors for T1D, but our study does not support an independent association between MICA variants and T1D.     

Genome-wide screen in obese pedigrees with type 2 diabetes mellitus from a defined Dutch population

A genome scan was performed in obese type 2 diabetes mellitus pedigrees to identify susceptibility loci involved in obesity-driven type 2 diabetes mellitus. We studied the 20% most obese diabetes pedigrees from a confined Dutch population from around the town of Breda. Previously we, and others, have already shown that a susceptibility locus influencing obesity in diabetes may reside on chromosome 18p11. We now report evidence to also suggest linkage for type 2 diabetes in these obese pedigrees on chromosome regions 11p (genome-wide P-value 相似文献   

Genome-wide analysis shows no genomic predictors of ovarian response to stimulation by exogenous FSH for IVF

The current proof of principle study explores the possibility that a genetic single-nucleotide polymorphism (SNP) profile is associated with ovarian response to standardized stimulation for IVF using exogenous FSH. Such a pharmacogenomic approach could aid in rendering ovarian stimulation for IVF more tailored to the patient, potentially improving the delicate balance between efficacy, side effects and chances for complications. Genome-wide association (GWA) analysis using Illumina Human 610-Quad BeadChips was used in a homogeneous group of 102 healthy, Caucasian, regularly cycling, non-smoking women aged 38 years or less with a body mass index <30 kg/m2 with a regular indication for IVF in a tertiary referral University Hospital. Genetic profiles were associated with the number of oocytes obtained. Ovarian response varied widely, ranging from cancellation (less than three follicles) to more than 20 oocytes. After correction for multiple testing, no SNPs were observed to be significantly correlated to ovarian response, embryo quality or pregnancy. Restricting the information to SNPs involved in granulosa cell function, cell cycle regulation or apoptosis also did not yield significant associations for ovarian response. A study in a larger cohort is warranted, aiming to further explore subtle genetic variants with greater power.     

Shared genetics in coeliac disease and other immune-mediated diseases

Identifying disease-associated variants can improve the predictive models of disease risk and provide mechanistic insights into disease development. Coeliac disease (CD) is the only autoimmune trait with a known environmental trigger, which makes it an excellent model for studying the complexity of genetic and environmental factors in the development of autoimmunity. In this review, we will focus on the genetic loci that have recently been associated with CD and that contain genes involved in innate and adaptive immunity. Some of these loci are shared with other immune-mediated diseases, suggesting an overlap of the genetic mechanisms involved in the development of such diseases. Some therapies, e.g. tumour necrosis factor inhibitors or a gluten-free diet, are already proving effective for more than one autoimmune disease. Follow-up of individuals with a high genetic risk of CD and other autoimmune diseases could help to elucidate the role of environmental factors (such as infectious agents or alterations in the microbiome) and prevent disease development.