Study of polymorphisms in 4q27, 10p15, and 22q13 regions in autoantibodies stratified type 1 diabetes patients.

Type 1 diabetes (T1D) is a multifactorial disease mainly associated with the human leukocyte antigen region. Previous studies suggested the association of interleukin-2 (IL2) gene polymorphisms and its alpha- and beta-chain receptor (IL2RA and IL2RB) variants with different autoimmune diseases such as T1D, celiac disease, multiple sclerosis, and rheumatoid arthritis. All T1D studies were conducted in diabetic patients younger than 17 years at diagnosis. The aim of our study was to replicate these associations not only in pediatric patients, but also in individuals with late onset. We performed a genetic association study of chromosomal regions 4q27, 10p15, and 22q13 containing the IL2, IL2RA, and IL2RB genes in 445 T1D subjects and 828 healthy controls. Seven single nucleotide polymorphisms (SNPs) were selected, previously described as genetic factors related to several autoimmune diseases, and were analyzed by TaqMan assays. The reported association with T1D patients of the IL2RA-rs41295061 located in the 10p15 region was replicated and our data suggest a trend of association of the polymorphisms IL2-rs17388568 and IL2-rs6822844 in 4q27. The effect of these markers was independent of the age at disease onset. Furthermore, the polymorphisms studied in 4q27 were not dependent on the presence of autoantibodies; however, the effect of the associated SNP in 10p15 (IL2RA-rs41295061) was specific of patients sera positive for diabetes antibodies. In conclusion, our results seem to indicate that late-onset and young T1D patients share most genetic factors located in the studied regions, but some markers could correlate with the presence of T1D specific autoantibodies.

A polymorphism in PTPN2 gene is associated with an earlier onset of type 1 diabetes.

The Wellcome Trust Case Control Consortium (WTCCC) genome-wide study found association of PTPN2 with three autoimmune diseases, among them is type 1 diabetes (T1D). This result was confirmed by a follow-up study that pointed to new independent signals within the region. However, both studies were performed in patients with an early-onset T1D. We aimed at replicating the previous results and studying the influence of these polymorphisms in the age at T1D debut. We genotyped 439 T1D Spanish subjects (age at onset, 1 to 65 years) and 861 controls for two PTPN2 single nucleotide polymorphisms (SNPs), rs2542151 and rs478582, and studied the effect of both polymorphisms in age at onset through stratified and continuous analyses. The frequency of rs2542151*G carriers was significantly higher in the early-onset group compared with late-onset patients (p = 0.023) and with controls (OR = 1.61 [1.14-2.26]; p = 0.005). No significant differences were found between controls and late-onset patients. The log-rank chi-square test for the Kaplan-Meier plots (carriers of susceptibility allele vs non carriers) was statistically significant (χ (1df) (2) = 4.485; p = 0.034), yielding an earlier disease debut for G carriers. The analysis of the SNP rs478582 did not reach statistical significance. In summary, we replicate the association detected by the WTCCC and propose that the rs2542151*G allele confers risk to an earlier onset of T1D.

Polymorphisms in the selenoprotein S gene: lack of association with autoimmune inflammatory diseases.

BACKGROUND: Selenoprotein S (SelS) protects the functional integrity of the endoplasmic reticulum against the deleterious effects of metabolic stress. SEPS1/SelS polymorphisms have been involved in the increased release of pro-inflammatory cytokines interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha and IL-6 in macrophages. We aimed at investigating the role of the SEPS1 variants previously associated with higher plasma levels of these cytokines and of the SEPS1 haplotypes in the susceptibility to develop immune-mediated diseases characterized by an inflammatory component. RESULTS: Six polymorphisms distributed through the SEPS1 gene (rs11327127, rs28665122, rs4965814, rs12917258, rs4965373 and rs2101171) were genotyped in more than two thousand patients suffering from type 1 diabetes, rheumatoid arthritis or inflammatory bowel diseases and 550 healthy controls included in the case-control study. CONCLUSION: Lack of association of SEPS1 polymorphisms or haplotypes precludes a major role of this gene increasing predisposition to these inflammatory diseases.

Association of MYO9B haplotype with type 1 diabetes.

MYO9B (myosin IXB) polymorphisms were associated with celiac disease and ulcerative colitis susceptibility, presumably through alteration of the intestinal permeability. Recently this gene was also associated with several diseases with an autoimmune component, such as rheumatoid arthritis and systemic lupus erythematosus. We aimed to test, for the first time, the potential role of MYO9B polymorphisms in type 1 diabetes (T1D), an autoimmune condition preceded by changes in intestinal barrier integrity. Three previously associated MYO9B polymorphisms (rs962917, rs2279003, and rs2305764) were studied in 316 T1D patients and 706 ethnically matched controls. Minor alleles of those polymorphisms were more frequent in diabetic patients than in controls and the haplotype carrying major alleles in those positions, rs962917*G/rs2279003*C/rs2305764*G, significantly reduced the risk of T1D in the Spanish population (p = 0.004; OR [95% confidence interval] = 0.68 [0.52-0.90]). Our data suggest an involvement of this MYO9B chromosomal region in T1D predisposition, indicating extensive influence on autoimmune diseases.

IFIH1-GCA-KCNH7 locus: influence on multiple sclerosis risk.

A recent genome-wide scan of nonsynonymous SNPs and ulterior validation in case-control and family analyses evidenced a susceptibility locus for type 1 diabetes (T1D) on chromosome 2q24.3. We aimed at testing the effect of this locus in other autoimmune diseases with complex genetic background, such as multiple sclerosis (MS). Four SNPs along the locus, rs13422767, rs2111485, rs1990760 and rs2068330, were genotyped using TaqMan MGB chemistry in 311 T1D and 412 MS patients and 535 ethnically matched healthy controls. The previously reported association of this locus was found for the first time in MS (rs2068330, G vs C: P=0.001; OR (95% CI)=0.73 (0.6-0.88)) and a trend for replication was observed in our Spanish diabetic cohort. Therefore, genes included in this locus - IFIH1 interferon induced helicase, GCA grancalcin or the potassium channel KCNH7 - are potential candidates implicated in the pathogenesis of these autoimmune diseases, although strong linkage disequilibrium in the region hampered further localization of the etiologic gene.

IL4 in the 5q31 context: association studies of type 1 diabetes and rheumatoid arthritis in the Spanish population.

IL4, the gene coding the prototypic Th2 cytokine, has been frequently studied in the context of several inflammatory conditions, but conclusive results have not been obtained. This gene is located in the 5q31-33 complex genetic region, which shows some susceptibility factors to type 1 diabetes (T1D) and rheumatoid arthritis (RA) among other inflammatory conditions. Our aim was to assess the involvement on T1D and RA of IL4 polymorphisms considered individually and in combination with other polymorphisms in 5q31-33, specifically in the OCTN locus, where the L503F polymorphism has been associated with Crohn's disease and other Th1 diseases. We performed a case-control study including 316 T1D patients, 599 RA patients and 540 healthy controls, all of them corresponding to white Spanish individuals. The IL4 single-nucleotide polymorphisms (SNPs) -590C/T (rs2243250) and the OCTN1 exonic SNP L503F (rs1050152) were analysed in all samples. Frequency comparisons of -590C/T and stratified analysis including both cited SNPs were performed using chi-square tests. The -590C/T IL4 SNP was not found associated with T1D or RA when individual analyses were performed. However, a significant association with T1D emerged after stratification by L503F [p=0.02, odds ratio=1.95, 95% CI=1.07-3.55]. The location of the IL4 gene in the complex 5q31-33 genetic region, which contains many genes involved in immunological responses and presents linkage disequilibrium extended along many kilobases, makes necessary to interpret cautiously the previous IL4-association studies.

Susceptibility to type 1 diabetes conferred by the PTPN22 C1858T polymorphism in the Spanish population.

BACKGROUND: The protein tyrosine phosphatase N22 gene (PTPN22) encodes a lymphoid-specific phosphatase (LYP) which is an important downregulator of T cell activation. A PTPN22 polymorphism, C1858T, was found associated with type 1 diabetes (T1D) in different Caucasian populations. In this study, we aimed at confirming the role of this variant in T1D predisposition in the Spanish population. METHODS: A case-control was performed with 316 Spanish white T1D patients consecutively recruited and 554 healthy controls, all of them from the Madrid area. The PTPN22 C1858T SNP was genotyped in both patients and controls using a TaqMan Assay in a 7900 HT Fast Real-Time PCR System. RESULTS: We replicated for the first time in a Spanish population the association of the 1858T allele with an increased risk for developing T1D [carriers of allele T vs. CC: OR (95%) = 1.73 (1.17-2.54); p = 0.004]. Furthermore, this allele showed a significant association in female patients with diabetes onset before age 16 years [carriers of allele T vs. CC: OR (95%) = 2.95 (1.45-6.01), female patients vs female controls p = 0.0009]. No other association in specific subgroups stratified for gender, HLA susceptibility or age at onset were observed. CONCLUSION: Our results provide evidence that the PTPN22 1858T allele is a T1D susceptibility factor also in the Spanish population and it might play a different role in susceptibility to T1D according to gender in early-onset T1D patients.

Evidence for the association of the SLC22A4 and SLC22A5 genes with type 1 diabetes: a case control study.

BACKGROUND: Type 1 diabetes (T1D) is a chronic, autoimmune and multifactorial disease characterized by abnormal metabolism of carbohydrate and fat. Diminished carnitine plasma levels have been previously reported in T1D patients and carnitine increases the sensitivity of the cells to insulin. Polymorphisms in the carnitine transporters, encoded by the SLC22A4 and SLC22A5 genes, have been involved in susceptibility to two other autoimmune diseases, rheumatoid arthritis and Crohn's disease. For these reasons, we investigated for the first time the association with T1D of six single nucleotide polymorphisms (SNPs) mapping to these candidate genes: slc2F2, slc2F11, T306I, L503F, OCTN2-promoter and OCTN2-intron. METHODS: A case-control study was performed in the Spanish population with 295 T1D patients and 508 healthy control subjects. Maximum-likelihood haplotype frequencies were estimated by applying the Expectation-Maximization (EM) algorithm implemented by the Arlequin software. RESULTS: When independently analyzed, one of the tested polymorphisms in the SLC22A4 gene at 1672 showed significant association with T1D in our Spanish cohort. The overall comparison of the inferred haplotypes was significantly different between patients and controls (chi2 = 10.43; p = 0.034) with one of the haplotypes showing a protective effect for T1D (rs3792876/rs1050152/rs2631367/rs274559, CCGA: OR = 0.62 (0.41-0.93); p = 0.02). CONCLUSION: The haplotype distribution in the carnitine transporter locus seems to be significantly different between T1D patients and controls; however, additional studies in independent populations would allow to confirm the role of these genes in T1D risk.

Th1 cytokine polymorphisms in spanish patients with type 1 diabetes.

Several polymorphisms in regions where Th1 cytokines (IL12B and IFNG genes) are located were analyzed in 303 Spanish subjects with type 1 diabetes and compared with a control cohort (n = 548). Both groups comprised residents of the Madrid area. The haplotype frequencies were estimated by the expectation-maximization algorithm, and p values were corrected by the number of haplotypes taken into account in the study. Two haplotypes were significantly associated with the disease, one in the IL12B region (D5S2038*8/D5S1352*2/SNP1188C; OR = 3.01, p(c) = 0.0255) and another involved the IFNGgene (D12S313*9/IFNG*1; OR = 1.58, p(c) = 0.0217). Furthermore, a protective IL12B haplotype was found (D5S2038*4/D5S1352*1/SNP1188A; OR = 0.40, p(c) = 0.0405). No association was found for any of IL12B and IFNG markers individually.

[Management of type 2 diabetic patients in primary care in Spain]. / Tratamiento de los pacientes con diabetes mellitus tipo 2 en atención primaria en España.

BACKGROUND AND OBJECTIVE: We assess the metabolic control, complications, quality of life related to health (QLRH) and the type and amount of medical resource consumption (MRC) in type 2 diabetic patients (2DMp) followed by primary care physicians (PCP) in Spain. PATIENTS AND METHOD: We studied 628 2DMp divided in 4 cohorts: 1. Either newly diagnosed 2DMp who required pharmacological treatment or failed to non-pharmacological measures; 2. Patients pharmacologically treated for less than 1 year; 3. Patients with pharmacological treatment for more than 1 year; 4. Patients with impaired fasting glucose (control group). RESULTS: Eighty percent of the subjects were overweight. At baseline, 27.9, 23.5 and 36.9% of patients from cohorts 1, 2 and 3, respectively, had HbA1C < 8%. After 6 months of follow-up, 14.6, 21.3 and 22.8% of patients from cohorts 1, 2 and 3, respectively, still had "bad control". At baseline, 38.0%, 21.2% and 20.7% of patients from cohorts 1, 2, and 3, respectively, had "bad lipid profile". After 6 months, 57.4%, 54.2% and 45.3% of cohorts 1, 2 and 3, respectively, still had plasma cLDL levels > 130 mg/dl. Complications were more frequent in cohort 3. During the 6-month period, MRC was higher among 2DMp than controls (p < 0.05) and higher among patients from cohort 3 (p < 0.05) compared with all the other patients. More diabetic than control patients and more patients from cohort 3 than patients from cohort 1 and 2 reported that their expected quality of life would be better without diabetes. CONCLUSIONS: One out of four of diabetic patients studied had HbA1C and lipids higher than the limits suggested by guidelines. Type 2 diabetes is associated with higher MRC and worse QLRH. This situation is worse among long-term diabetic patients.

Type 1 diabetes in the Spanish population: additional factors to class II HLA-DR3 and -DR4.

BACKGROUND: The Major Histocompatibility Complex is the main genetic contributor to susceptibility to type 1 diabetes (T1D); genome-wide scans have consistently mapped increased predisposition to this region. The highest disease risk has been associated with HLA-DR3 and HLA-DR4. In particular, the DR3-positive ancestral haplotype 18.2 was reported as highly diabetogenic. We aimed to corroborate whether this haplotype increases the susceptibility conferred by the DQ2-DR3 alleles in a Mediterranean population. We also searched for additional susceptibility factors to the classic DQ2-DR3 and DQ8-DR4. RESULTS: Genetic MHC markers were analysed in a case-control study with 302 T1D patients and 529 ethnically matched controls. DR3-TNFa1b5 carrier rate was significantly higher in DR3-positive heterozygous T1D patients than in DR3-positive heterozygous controls (p = 0.0019; odds ratio OR [95% confidence interval CI] = 2.26 [1.3-3.93]). This data was confirmed analysing the allelic frequency, which includes the information corresponding to the DR3-homozygous individuals (p = 0.001; OR = 2.09) and by using the Arlequin software to check the DR3-positive haplotypes (p = 0.004;OR = 1.93). The present results provide strong evidence of a second susceptibility region in the ancestral haplotype 18.2 in the Spanish population. Moreover, we searched for T1D susceptibility factors in addition to the MHC classical ones, within the DR2-DQ6/DR3-DQ2/DR4-DQ8 negative population. Several genetic markers in both MHC class II (DQA1*0101-DQB1*0501 [p = 0.007;OR = 2.81], DQA1*0201-DQB1*0202 [p = 0.03; OR = 2.35]) and III (TNFa2b1 [p = 0.01 OR = 2.74], BAT-2*2 [p = 0.004; OR = 3.19]) were found. These different alleles associated with T1D were not independent and we observed linkage disequilibrium among them leading us to describe two new risk haplotypes (DQA1*0101-DQB1*0501-TNFa2b1 and DQA1*0201-DQB1*0202- BAT-2*2). Finally, we studied a T1D susceptibility/protection marker located in extended class I, D6S2223; however, no association was observed in our population. CONCLUSION: Our results suggest that other associated MHC haplotypes might present susceptibility factors in loci different from HLA-class II and that the class II molecules are not necessarily the universal etiologic factor in every MHC haplotype.

[Evaluation on the compliance of the metabolic control aims in outpatients with type 2 diabetes mellitus in Spain. The TranSTAR study]. / Evaluación del cumplimiento de los objetivos de control metabólico de la diabetes mellitus tipo 2. Estudio TranSTAR.

BACKGROUND AND OBJECTIVE: A good metabolic control of patients with type 2 diabetes mellitus (DM2) will likely contribute to a decrease of their cardiovascular (CV) risk. Our aim was (1) to evaluate the degree of metabolic control with regard to glycemia, lipidemia and blood pressure (BP) and (2) to describe the prevalence of hypertension (HT) and hyperlipidemia in DM2 outpatients. PATIENTS AND METHOD: TranSTAR is an on-line, case-control, cross-sectional study, which was performed in outpatient from all around Spain. Data on basal glycemia (BG), glycosilated hemoglobin (A1C), lipid profile, BP and personal history of CV diseases were obtained. The postprandial glycemia (PPG) was measured in a capillary sample at 1-3 hours post-meal. Standards of metabolic control of the Sociedad Española de Diabetes were applied to evaluate the degree of glycemic, lipidemic and BP control. RESULTS: 371 pairs of patients were studied. In DM2 patients, a bad control was observed in 82.1% (CI 95%, 77.9-86.3) of them according to BG, in 88.4% (85.1-91.7) according to PPG and in 18.8% (14.3-23.3) according to A1C. An insufficient control in lipid profile was noticed in 63.3% (56.6-70.0) and in BP in 69.5% (64.2-74.8). 9.2% (0.9-17.5) and 20.5% (12.8-28.2) DM2 subjects had an unknown HT and hyperlipidemia, respectively. CONCLUSION: The rate of DM2 outpatients with a bad metabolic control is very high. The availability of data from our own population should contribute to a better clinical management of these patients.