Ovarian cancer pathology characteristics as predictors of variant pathogenicity in BRCA1 and BRCA2.

BACKGROUND: The distribution of ovarian tumour characteristics differs between germline BRCA1 and BRCA2 pathogenic variant carriers and non-carriers. In this study, we assessed the utility of ovarian tumour characteristics as predictors of BRCA1 and BRCA2 variant pathogenicity, for application using the American College of Medical Genetics and the Association for Molecular Pathology (ACMG/AMP) variant classification system. METHODS: Data for 10,373 ovarian cancer cases, including carriers and non-carriers of BRCA1 or BRCA2 pathogenic variants, were collected from unpublished international cohorts and consortia and published studies. Likelihood ratios (LR) were calculated for the association of ovarian cancer histology and other characteristics, with BRCA1 and BRCA2 variant pathogenicity. Estimates were aligned to ACMG/AMP code strengths (supporting, moderate, strong). RESULTS: No histological subtype provided informative ACMG/AMP evidence in favour of BRCA1 and BRCA2 variant pathogenicity. Evidence against variant pathogenicity was estimated for the mucinous and clear cell histologies (supporting) and borderline cases (moderate). Refined associations are provided according to tumour grade, invasion and age at diagnosis. CONCLUSIONS: We provide detailed estimates for predicting BRCA1 and BRCA2 variant pathogenicity based on ovarian tumour characteristics. This evidence can be combined with other variant information under the ACMG/AMP classification system, to improve classification and carrier clinical management.

Toll-Like Receptor 1 Locus Re-examined in a Genome-Wide Association Study Update on Anti-Helicobacter pylori IgG Titers.

BACKGROUND & AIMS: A genome-wide significant association between anti-Helicobacter pylori (H pylori) IgG titers and Toll-like receptor (TLR1/6/10) locus on 4p14 was demonstrated for individuals of European ancestry, but not uniformly replicated. We re-investigated this association in an updated genome-wide association study (GWAS) meta-analysis for populations with low gastric cancer incidence, address potential causes of cohort heterogeneity, and explore functional implications of genetic variation at the TLR1/6/10 locus. METHODS: The dichotomous GWAS (25% individuals exhibiting highest anti-H pylori IgG titers vs remaining 75%) included discovery and replication sampls of, respectively, n = 15,685 and n = 9676, all of European ancestry. Longitudinal analysis of serologic data was performed on H pylori-eradicated subjects (n = 132) and patients under surveillance for premalignant gastric lesions (n = 107). TLR1/6/10 surface expression, TLR1 mRNA, and cytokine levels were measured in leukocyte subsets of healthy subjects (n = 26) genotyped for TLR1/6/10 variants. RESULTS: The association of the TLR1/6/10 locus with anti-H pylori IgG titers (rs12233670; ß = -0.267 ± SE 0.034; P = 4.42 × 10-15) presented with high heterogeneity and failed replication. Anti-H pylori IgG titers declined within 2-4 years after eradication treatment (P = 0.004), and decreased over time in patients with premalignant gastric lesions (P < 0.001). Variation at the TLR1/6/10 locus affected TLR1-mediated cytokine production and TLR1 surface expression on monocytes (P = 0.016) and neutrophils (P = 0.030), but not mRNA levels. CONCLUSIONS: The association between anti-H pylori IgG titers and TLR1/6/10 locus was not replicated across cohorts, possibly owing to dependency of anti-H pylori IgG titers on therapy, clearance, and antibody decay. H pylori-mediated immune cell activation is partly mediated via TLR1 signaling, which in turn is affected by genetic variation.

Association of human leukocyte antigen class II alleles with epithelial cell apoptosis and extracellular matrix production in acute COVID-19.

Introduction: Pathogenic mechanisms and long-term consequences of COVID-19 require attention in studies on SARS-CoV-2. The association of the severity of COVID-19 with genetic factors, such as human leukocyte antigen (HLA) genes, remains underexplored. Our study assessed the relationships between HLA class II alleles and COVID-19 severity and blood-based indicators of systemic inflammation and organ damage, serum markers of epithelial cell apoptosis such as caspase-cleaved CK18 fragment M30 (CK18-M30) and the extracellular matrix product hyaluronic acid (HA). Material and methods: The study included 101 hospitalized COVID-19 patients (mean age 60 ±14 years). Clinical tests were performed at admission to the hospital. The levels of CK18-M30 and HA were detected in serum by enzyme-linked immunosorbent assay (ELISA). HLA typing was performed in HLA-DRB1, -DQA1, and -DQB1 loci by the polymerase chain reaction with low-resolution sequence-specific primers. Results: Sixty-one patients had a non-severe and 40 had a severe or critical disease course (following the WHO definition). The severity was associated with older age, male gender, higher HA, CK18-M30, and some indicators of inflammation. Despite the lack of direct association between HLA alleles and the severity of COVID-19, the presence of HLA-DRB1*04 and 12 alleles in the genotype was associated with lowered or elevated HA, respectively. The HLA-DQB1*03:01 allele was associated with lowered CK18-M30, aspartate aminotransferase, and ferritin. In addition, HLA-DQB1*06:01 was associated with elevated alanine aminotransferase. Conclusions: Associations of HLA class II alleles with markers of epithelial cell apoptosis and extracellular matrix production indirectly support the influence of HLA genes on acute COVID-19 severity.

Polymorphism rs2066865 in the Fibrinogen Gamma Chain (FGG) Gene Increases Plasma Fibrinogen Concentration and Is Associated with an Increased Microvascular Thrombosis Rate.

Background and Objective: Thrombosis due to inherited hypercoagulability is an issue that has been raised in microvascular flap surgery previously. We analyzed the association of a single nucleotide polymorphism (SNP) in rs2066865 in the fibrinogen gamma chain (FGG) gene, alteration in plasma fibrinogen concentration, and presence of microvascular flap thrombosis. Materials and Methods: A total of 104 adult patients with microvascular flap surgery were subjected to an analysis of the presence of SNP rs2066865 in the FGG gene. Alterations in plasma fibrinogen concentration according to genotype were determined as a primary outcome, and flap thrombosis was defined as a secondary outcome. Results: Flap thrombosis was detected in 11.5% of patients (n = 12). Successful revision of anastomosis was performed in four patients, resulting in a microvascular flap survival rate of 92.3%. We observed an increase in plasma fibrinogen concentration in genotype G/A and A/A carriers (G/G, 3.9 (IQR 4.76-3.04); G/A, 4.28 (IQR 5.38-3.18); A/A, 6.87 (IQR 8.25-5.49) (A/A vs. G/A, p = 0.003 and A/A vs. G/G, p = 0.001). Within group differences in microvascular flap thrombosis incidence rates were observed-G/G 6/79 (7.59%); G/A 5/22 (22.7%); A/A 1/3 (33.3%) (OR 0.30 95%; CI 0.044 to 0.57), p = 0.016; RR 3.2-when G/G versus G/A and A/A were analyzed respectively. Conclusions: A/A and G/A genotype carriers of a single nucleotide polymorphism in rs2066865 in the fibrinogen gamma chain gene had a higher plasma fibrinogen concentration, and this might be associated with an increased microvascular flap thrombosis incidence rate. Determined polymorphism could be considered as a genetic marker associated with microvascular flap thrombosis development. To confirm the results of this study, the data should be replicated in a greater sample size.

Genome Database of the Latvian Population (LGDB): Design, Goals, and Primary Results.

BACKGROUND: The Genome Database of the Latvian Population (LGDB) is a national biobank that collects, maintains, and processes health information, data, and biospecimens collected from representatives of the Latvian population. These specimens serve as a foundation for epidemiological research and prophylactic and therapeutic purposes. METHODS: Participant recruitment and biomaterial and data processing were performed according to specifically designed standard protocols, taking into consideration international quality requirements. Legal and ethical aspects, including broad informed consent and personal data protection, were applied according to legal norms of the Republic of Latvia. RESULTS: Since its start in 2006, the LGDB is comprised of biosamples and associated phenotypic and clinical information from over 31,504 participants, constituting approximately 1.5% of the Latvian population. The LGDB represents a mixed-design biobank and includes participants from the general population as well as disease-based cohorts. The standard set of biosamples stored in the LGDB consists of DNA, plasma, serum, and white blood cells; in some cohorts, these samples are complemented by cancer biopsies and microbiome and urine samples. The LGDB acts as a core structure for the Latvian Biomedical Research and Study Centre (BMC), representing the national node of Latvia in Biobanking and BioMolecular resources Research Infrastructure - European Research Infrastructure Consortium (BBMRI-ERIC). CONCLUSIONS: The development of the LGDB has enabled resources for biomedical research and promoted genetic testing in Latvia. Further challenges of the LGDB are the enrichment and harmonization of collected biosamples and data, the follow-up of selected participant groups, and continued networking and participation in collaboration projects.

Polymorphisms on PAI-1 and ACE genes in association with fibrinolytic bleeding after on-pump cardiac surgery.

BACKGROUND: Carriers of plasminogen activator inhibitor -1 (PAI-1) -675 genotype 5G/5G may be associated with lower preoperative PAI-1 plasma levels and higher blood loss after heart surgery using cardiopulmonary bypass (CPB). We speculate if polymorphisms of PAI-1 -844 A/G and angiotensin converting enzyme (ACE) intron 16 I/D also might promote fibrinolysis and increase postoperative bleeding. METHODS: We assessed PAI-1 -844 A/G, and ACE intron 16 I/D polymorphisms by polymerase chain reaction technique and direct sequencing of genomic DNA from 83 open heart surgery patients that we have presented earlier. As primary outcome, accumulated chest tube drainage (CTD) at 4 and 24 h were analyzed for association with genetic polymorphisms. As secondary outcome, differences in plasma levels of PAI-1, t-PA/PAI-1 complex and D-dimer were determined for each polymorphism. SPSS® was used for statistical evaluation. RESULTS: The lowest preoperative PAI-1 plasma levels were associated with PAI-1 -844 genotype G/G, and higher CTD, as compared with genotype A/A at 4 and 24 h after surgery. Correspondingly, 4 h after the surgery CTD was higher in carriers of ACE intron 16 genotype I/I, as compared with genotype D/D. PAI-1 plasma levels and t-PA/PAI-1 complex reached nadir in carriers of ACE intron 16 genotype I/I, in whom we also noticed the highest D-dimer levels immediately after surgery. Notably, carriers of PAI-1 -844 genotype G/G displayed higher D-dimer levels at 24 h after surgery as compared with those of genotype A/G. CONCLUSIONS: Increased postoperative blood loss secondary to enhanced fibrinolysis was associated with carriers of PAI-1 -844 G/G and ACE Intron 16 I/I, suggesting that these genotypes might predict increased postoperative blood loss after cardiac surgery using CPB.

Association of genetic variation in the organic cation transporters OCT1, OCT2 and multidrug and toxin extrusion 1 transporter protein genes with the gastrointestinal side effects and lower BMI in metformin-treated type 2 diabetes patients.

OBJECTIVE: Metformin is the most widely used oral antidiabetic drug for the treatment of type 2 diabetes (T2D). So far, the number of polymorphisms in SLC22A1, SLC22A2, and SLC47A1 genes coding for organic cation transporter 1 (OCT1), OCT2, and multidrug and toxin extrusion transporter 1 (MATE1) metformin transporters have been described in association with the efficacy of metformin. However, there is no information on the influence of genetic variations within these genes on the side effects of metformin. In this study, we assessed whether five single-nucleotide polymorphisms and two indel polymorphisms are associated with the side effects of metformin in patients with T2D. METHODS: Seven polymorphisms in OCT1, OCT2, and MATE1 genes were compared between 53 T2D patients with side effects of metformin and 193 metformin users without symptoms of metformin intolerance. RESULTS: We found a statistically significant association between the A allele of the rs628031 (P=0.012, odds ratio=0.389, confidence interval 95% [0.186-0.815]) as well as 8 bp insertion (rs36056065) in the OCT1 gene (P=0.002, odds ratio=0.405, confidence interval 95% [0.226-0.724]) and the presence of the side effects of metformin. CONCLUSION: Two genetic variations in OCT1 that are in strong linkage disequilibrium may predispose toward an increased prevalence of the side effects of metformin in patients with T2D.

A novel EDA variant causing X-linked hypohidrotic ectodermal dysplasia: Case report.

Hereditary ectodermal dysplasias are a complex group of inherited disorders characterised by abnormalities in two or more ectodermal derivatives (skin, nails, sweat glands, etc.). There are two main types of these disorders - hidrotic and hypohidrotic/anhidrotic ectodermal dysplasias. Hypohidrotic ectodermal dysplasia (HED) or Christ-Siemens-Touraine syndrome (OMIM: 305100) occurs in 1 out of 5000-10,000 births [19] and has an X-linked recessive inheritance pattern (X-linked hypohydrotic ectodermal dysplasia - XLHED) [2]. The main cause of XLHED is a broad range of pathogenic variants in the EDA gene (HGNC:3157, Xq12-13) which encodes the transmembrane protein ectodysplasin-A [4]. We report here the case of a patient with a novel inherited allelic variant in the EDA gene - NM_001399.5:c.337C>T (p.Gln113*) - in the heterozygous state. Targeted family member screening was conducted and other carriers of this EDA gene pathogenic variant were identified and phenotypically characterised. The patient subsequently underwent in vitro fertilisation with preimplantation genetic testing for monogenic diseases (PGT-M).

Polymorphisms in MEN1 and DRD2 genes are associated with the occurrence and characteristics of pituitary adenomas.

OBJECTIVE: Although pituitary adenomas (PAs) affect a significant proportion of the population, only a fraction have the potential to become clinically relevant during an individual's lifetime, causing hormonal imbalance or complications due to mass effect. The overwhelming majority of cases are sporadic and without a clear familial history, and the genotype-phenotype correlation in PA patients is poorly understood. Our aim was to investigate the involvement of genes known for their role in familial cases on drug response and tumor suppression in the development and pathology of PAs in a patient group from Latvia. DESIGN: The study included 143 cases and 354 controls, we investigated the role of single-nucleotide polymorphisms (SNPs) in seven genes (SSTR2, SSTR5, DRD2, MEN1, AIP, GNAS, and PRKAR1A) associated with pituitary tumor occurrence, phenotype, and clinical symptoms. METHODS: Genotyping of 96 tag and nonsynonymous SNPs was performed in the genomic regions of interest. RESULTS: We discovered a significant association (OR=17.8, CI 0.95=2.18-145.5, P=0.0002) between a rare MEN1 mutation (rs2959656) and clinically active adenoma in our patients. Additionally, rs7131056 at DRD2 was associated with a higher occurrence of extrasellar growth in patients with prolactinoma and somatotropinoma (OR=2.79, CI 0.95=1.58-4.95, P=0.0004). CONCLUSIONS: rs2959656, a nonsynonymous variant in MEN1, is associated with the development of clinically active PA. Furthermore, rs7131056 in DRD2 contributes to either faster growth of the adenoma or reduced symptomatic presentation, allowing PAs to become larger before detection.

Single nucleotide polymorphisms in the intergenic region between metformin transporter OCT2 and OCT3 coding genes are associated with short-term response to metformin monotherapy in type 2 diabetes mellitus patients.

OBJECTIVES: High variability in clinical response to metformin is often observed in type 2 diabetes (T2D) patients, and it highlights the need for identification of genetic components affecting the efficiency of metformin therapy. Aim of this observational study is to evaluate the role of tagSNPs (tagging single nucleotide polymorphisms) from genomic regions coding for six metformin transporter genes with respect to the short-term efficiency. DESIGN: 102 tagSNPs in 6 genes coding for metformin transporters were genotyped in the group of 102 T2D patients treated with metformin for 3 months. METHODS: Most significant hits were analyzed in the group of 131 T2D patients from Slovakia. Pharmacokinetic study in 25 healthy nondiabetic volunteers was conducted to investigate the effects of identified polymorphisms. RESULTS: In the discovery group of 102 patients, minor alleles of rs3119309, rs7757336 and rs2481030 were significantly nominally associated with metformin inefficiency (P = 1.9 × 10-6 to 8.1 × 10-6). Effects of rs2481030 and rs7757336 did not replicate in the group of 131 T2DM patients from Slovakia alone, whereas rs7757336 was significantly associated with a reduced metformin response in combined group. In pharmacokinetic study, group of individuals harboring risk alleles of rs7757336 and rs2481030 displayed significantly reduced AUC∞ of metformin in plasma. CONCLUSIONS: For the first time, we have identified an association between the lack of metformin response and SNPs rs3119309 and rs7757336 located in the 5' flanking region of the genes coding for Organic cation transporter 2 and rs2481030 located in the 5' flanking region of Organic cation transporter 3 that was supported by the results of a pharmacokinetic study on 25 healthy volunteers.

Prevalence estimation of celiac disease in the general adult population of Latvia using serology and HLA genotyping.

BACKGROUND: Prevalence estimates for celiac disease (CD) depend on the method used. The role of deamidated gliadin peptide (DGP) and genetic testing in epidemiological studies and diagnostic settings of celiac disease (CD) has still to be established. OBJECTIVES: The objective of this article is to assess the prevalence of CD in Latvia by combining serological tests with DQ2.5/DQ8 testing. METHODS: A total of 1444 adults from a randomly selected cross-sectional general population sample were tested by ELISA for tTG IgA, DGP IgA and IgG antibodies (QUANTA Lite®, Inova Diagnostics Inc). Samples with tTG IgA ≥20U were tested for EMA IgA by indirect immunofluorescence assay, and all specimens with tTG IgA ≥15U were tested by QUANTA-Flash® chemiluminescent assays (CIA) (Inova Diagnostics Inc) for tTG IgA, DGP IgA and IgG. DQ2.5/8 was detected in individuals with any positive ELISA test and a subgroup of controls. RESULTS: Forty-three individuals (2.98%; 95% CI: 2.10-3.86%) tested positive by at least one ELISA test; 41.86% of the serology-positive individuals (any test above the cutoff) were DQ positive. Six individuals (0.42%; 95% CI: 0.09-0.75%) were triple ELISA positive, and DQ2.5 or DQ8 was positive in all; 0.35% (95% CI: 0.05-0.65%) were tTG IgA and EMA positive. Two tTG IgA-negative cases were both DGP IgG and IgA positive, both being DQ positive; including them in the "serology-positive" group would increase the prevalence to 0.49% (95% CI: 0.13-0.85%). CIA tests revealed 2 tTG IgA-positive and EMA-negative cases with a positive genotype. DQ2.5 or DQ8 genotype was positive in 28.6% of the serology-negative population. CONCLUSIONS: Estimates of the prevalence of CD in Latvia based on the serogenetic testing approach range from 0.35% to 0.49% depending on the criteria used. There is a rationale for combining serological tests and DQ2.5/8 genotyping.

Coxsackie virus B antibodies are increased in HLA DR3-MICA5.1 positive type 1 diabetes patients in the Linköping region of Sweden.

Type 1 diabetes mellitus (T1DM) is an autoimmune disorder in which genetics and environmental factors play a role. Among the environmental factors, viruses (especially Coxsackie virus B [CBV]), and among genetic markers, human leukocyte antigen (HLA) DRB1*04-DQA1*0301-DQB1*0302 (DR4-DQ8) and DRB1*03-DQA1*0501-DQB1*0201 (DR3-DQ2), and major histocompatibility complex class I chain-related gene-A (MICA) alleles 5 and 5.1 have been reported to be associated with T1DM in Caucasians. Sweden ranks third in the world for T1DM incidence. In Sweden, the Linköping region indicates the highest incidence for T1DM. In this study, we analyzed whether antibodies against CBV are increased in DR3, DR4, MICA5, or MICA5.1 positive patients from Linköping (n = 46) and from Swedish population as a whole (n = 298) between the age of 0 and 15 years old. There was no difference in the frequency of antibodies to CBV in patients compared with controls in Linköping (26% vs 23%) or in all of Sweden (26% vs 21%). However, CBV antibodies were increased in DR3, DR3-DR4 (heterozygous), DR3-MICA5.1, and DR3-DR4-MICA5.1 positive compared with DR3, DR3-DR4, DR3-MICA5.1, and DR3-DR4-MICA5.1 negative patients in Linköping (p < 0.05 for all), but not in Swedish population as a whole. Thus, our study suggests that in addition to DR3, MICA5.1 has an influence on the immune response to CBV infection in patients from Linköping.

MICA4/HLA-DRB1*04/TNF1 haplotype is associated with mixed connective tissue disease in Swedish patients.

In order to investigate major histocompatibility complex (MHC) class I chain-related gene A (MICA), tumor necrosis factor (TNFa), -308TNFA, and human leukocyte antigen (HLA-DR/DQ) polymorphisms in mixed connective tissue disease (MCTD), we analyzed 24 patients and 229 healthy controls from Sweden. MICA and TNFa typing was performed by polymerase chain reaction (PCR) and genotyping. HLA-DR and -DQ were genotyped using PCR-sequence specific primers (PCR-SSP) and PCR-sequence-specific oligonucleotide probe (PCR-SSOP), respectively. For analysis of -308TNFA polymorphisms we performed PCR with restriction endonuclease enzymes. We found that the MICA5.1-5.1 genotype was positively associated with MCTD. Shared epitope genes (DRB1*01 and DRB1*04) were also significantly positively associated with MCTD. Polymorphism of -308TNFA was not differently distributed in MCTD patients compared with controls. Furthermore, we demonstrated that frequencies of three estimated haplotypes were increased in MCTD patients compared with controls. Interestingly, the haplotype with MICA allele 4 together with DRB1*04 and TNF1 alleles gives the most specific pattern for MCTD patients compared with controls. Our study demonstrates a clear contribution of HLA loci in susceptibility to MCTD in the Swedish population. Susceptibility to MCTD may be linked to the MICA4/HLA-DRB1*04/TNF1 haplotype and MICA 5.1-5.1 genotype. Mixed connective tissue disease was also associated with shared epitope genes, which in RA has been associated with a more severe disease. Whether these genotypes affect the clinical phenotype of MCTD needs to be determined.

Association between the transmembrane region polymorphism of MHC class I chain related gene-A and type 1 diabetes mellitus in Sweden.

Major histocompatibility complex (MHC) class I chain related gene-A (MIC-A) is associated with type 1 diabetes mellitus (T1DM) in other populations. We tested the association of MIC-A gene polymorphism with T1DM in Swedish Caucasians; if it has an age-dependent association; and if the association has an effect on gender. We studied 635 T1DM patients and 503 matched controls in the age group of 0-35 years old. MIC-A5 was significantly increased in T1DM compared with controls (odds ratio [OR] =1.81, p(c) < 0.0005). Logistic regression analysis revealed MIC-A5 association was independent of HLA. MIC-A5 with DR4-DQ8 or MIC-A5 with DR3-DQ2 gave higher OR than the OR obtained with either of them alone (OR = 1.81, 7.1, and 3.6, respectively). MIC-A5 was positively (OR = 2.48, p(c) < 0.0005) and MIC-A6 negatively associated (OR = 0.61, p(c) = 0.035) with the disease in < or = 20 years of age. The negative association of MIC-A6 in young onset was confirmed by logistic regression analysis. MIC-A5 was associated with the disease in males (OR = 2.05, p(c) = 0.0005). MIC-A6 conferred protection (OR = 0.098, p(c) = 0.032) in females heterozygous for DR3/DR4. In conclusion, MIC-A5 is associated with T1DM; the association was higher in individuals < or = 20 years old; and negative association of MIC-A6 was stronger in younger onset patients than in older onset patients.

Lack of association of CCR2-64I and CCR5-Delta 32 with type 1 diabetes and latent autoimmune diabetes in adults.

It is well known that type 1 diabetes mellitus (T1DM) is a complex genetic disease resulting from the autoimmune destruction of pancreatic beta cells. Several genes have been associated with susceptibility and/or protection for T1DM, but the disease risk is mostly influenced by genes located in the class II region of the major histocompatibility complex. The attraction of leukocytes to tissues is essential for inflammation and the beginning of autoimmune reaction. The process is controlled by chemokines, which are chemotactic cytolines. Some studies have shown that CCR2-64I and CCR5-Delta 32 might be important for protection of susceptibility to some immunologically-mediated disorders. In the present study, we demonstrate the lack of association between CCR2-64I and CCR5-Delta 32 gene polymorphism and TIDM and we describe a new method for a simple and more precise genotyping of the CCR2 gene.

Major histocompatibility complex class I chain related (MIC) A gene, TNFa microsatellite alleles and TNFB alleles in juvenile idiopathic arthritis patients from Latvia.

In order to analyze involvement of major histocompatibility complex class I chain-related gene A (MICA) and tumor necrosis factor a (TNFa) microsatellite polymorphisms as well as TNFB gene in juvenile idiopathic arthritis (JIA), we studied 128 patients divided into groups according to clinical features [monoarthritis (n = 14), oligoarthritis (n = 58), polyarthritis (n = 50), and systemic (n = 6)], and 114 age- and sex-matched healthy controls from Latvia. DNA samples were amplified with specific primers and used for genotyping of MICA and TNFa microsatellite. Typing for a biallelic NcoI polymerase chain reaction RFLP polymorphism located at the first intron of TNFB gene was done as follows: restriction digests generated fragments of 555bp and 185bp for TNFB*1 allele, and 740bp for TNFB*2 allele. The results were compared between cases and controls. We found significant increase of MICA allele A4 (p = 0.009; odds ratio [OR] = 2.3) and allele TNFa2 (p = 0.0001; OR = 4.4) in patients compared with controls. The frequency of allele TNFa9 was significantly decreased (p = 0.0001; OR = 0.1) in patients with JIA. No significant differences of TNFB allele frequency were found. Our data suggest that MICA and TNFa microsatellite polymorphisms may be used as markers for determination of susceptibility and protection from JIA.

Heterozygosity for MICA5.0/MICA5.1 and HLA-DR3-DQ2/DR4-DQ8 are independent genetic risk factors for latent autoimmune diabetes in adults.

Major histocompatibility complex class I chain-related gene A (MICA) encodes polymorphic, stress-inducible antigens recognized by gammadelta T cells within the intestinal epithelium. MICA microsatellite polymorphism has been implicated to be related to different autoimmune diseases. Ninety-eight patients with type 1 diabetes (median age, 35 years; range, 9-89 years and 51 patients with latent autoimmune diabetes (LADA; median age, 48 years; range, 19-79 years) were compared with 113 healthy control patients (median age, 35 years; range, 19-65 years) to study the importance of MICA-microsatellite polymorphism and HLA-DR-DQ as genetic risk factors for diabetes. The different factors were compared univariately and by logistic regression analysis. In the logistic regression model, heterozygosity for MICA5.0/5.1 was a significant risk factor for LADA (odds ratio [OR] = 12; 95% confidence interval [95%CI], 2.5-59) as well as heterozygosity for HLA-DR3-DQ2/DR4-DQ8 (OR = 15; 95%CI, 2.7-84). None of the MICA polymorphisms were related to type 1 diabetes. Heterozygosity for HLA-DR3-DQ2/DR4-DQ8 was a risk factor for type 1 diabetes (OR = 14; 95%CI, 2.9-66) as well as DR4-DQ8/x (OR = 2.8; 95%CI, 1.4-5.9). HLA-DR15-DQ6 was protective for type 1 diabetes (OR = 0.12; 95%CI, 0.015-0.96). We concluded that both heterozygosity for MICA5.0/5.1 and HLA-DR3-DQ2/DR4-DQ8 are separate risk factors for LADA, but that heterozygosity for HLA-DR3-DQ2/DR4-DQ8 and DR4-DQ8 alone are most important for type 1 diabetes.

MIC-A genotypes 4/5.1 and 9/9 are positively associated with type 1 diabetes mellitus in Brazilian population.

The aim of our study was to evaluate the frequencies of MIC-A alleles and genotypes in Brazilian patients with type 1 diabetes mellitus (T1DM) and healthy controls. MHC class I chain-related gene-A (MIC-A) has been shown to be associated with susceptibility to T1DM in different populations. We analyzed the DNA samples from 86 patients and 201 healthy controls for MIC-A by PCR amplification, and fragment sizes were determined in an ABI prism DNA sequencer. We found increased frequencies of two genotypes, MIC-A 4/5.1 (pc = 0.006; OR, 6.1) and 9/9 (pc = 0.045; OR, 5.75), in our patients (mean diagnosis age, 11.70 years; SD, 8.86; mean age, 20.44 years; SD, 12.17) compared with the controls (median age, 26.41 years; SD, 8.87).

Killer cell immunoglobulin-like receptor genes in Latvian patients with type 1 diabetes mellitus and healthy controls.

T1DM is very common in Sweden and is positively associated with HLA class II genes. Approximately 89% of the newly diagnosed patients carry the high-risk HLA DR4-DQ8 and DR3-DQ2. The remaining 11% develop T1DM without them. This can be due to involvement of other genes and environmental factors. Natural killer (NK) cells of the innate immune system are important in antiviral and antitumor immunity. They are implicated in the etiology of autoimmune T1DM. Human NK cells express killer cell immunoglobulin-like receptors (KIR) that belong to the polymorphic multigene family in chromosome 19q3.4. They modulate NK cell response by interacting with HLA class I. In addition, polymorphic MICA in HLA class I interacts with non-polymorphic NKG2D receptor on NK cells. We have studied, in addition to HLA-DR and -DQ, genes of the innate immune system MICA and KIR in Latvian patients (n = 98) with T1DM and controls (n = 100). They were genotyped using standard PCR-based typing methods. MICA allele 5 is positively associated with T1DM. KIR2DL2 and KIR2DS2 were both positively associated. Combined association of MICA4 and KIR2DL2 gave an odds ration (OR) of 26.7. However, the combined risk of KIR2DL2 and HLA class II genes, HLADR3 (OR = 73.4), DR4 (OR = 66.8), and DR3 and DR4 (OR = 88.3), was higher. The maximum risk was when KIR2DL2, MICA5, and DR3/DR4 were in combination. In conclusion, our results suggest that a balance between innate and acquired immunity is important, and an imbalance coud lead to T1DM.