Adán Valladares-Salgado

Candidate gene association study conditioning on individual ancestry in patients with type 2 diabetes and metabolic syndrome from Mexico City

Type 2 diabetes (T2D) is influenced by diverse environmental and genetic risk factors. Metabolic syndrome (MS) increases the risk of cardiovascular disease and diabetes. We analysed 14 cases of polymorphisms located in 10 candidate loci, in a sample of patients with T2D and controls from Mexico City.

Meta-analysis of lipid-traits in Hispanics identifies novel loci, population-specific effects, and tissue-specific enrichment of eQTLs.

We performed genome-wide meta-analysis of lipid traits on three samples of Mexican and Mexican American ancestry comprising 4,383 individuals, and followed up significant and highly suggestive associations in three additional Hispanic samples comprising 7,876 individuals. Genome-wide significant signals were observed in or near CELSR2, ZNF259/APOA5, KANK2/DOCK6 and NCAN/MAU2 for total cholesterol, LPL, ABCA1, ZNF259/APOA5, LIPC and CETP for HDL cholesterol, CELSR2, APOB and NCAN/MAU2 for LDL cholesterol, and GCKR, TRIB1, ZNF259/APOA5 and NCAN/MAU2 for triglycerides. Linkage disequilibrium and conditional analyses indicate that signals observed at ABCA1 and LIPC for HDL cholesterol and NCAN/MAU2 for triglycerides are independent of previously reported lead SNP associations. Analyses of lead SNPs from the European Global Lipids Genetics Consortium (GLGC) dataset in our Hispanic samples show remarkable concordance of direction of effects as well as strong correlation in effect sizes. A meta-analysis of the European GLGC and our Hispanic datasets identified five novel regions reaching genome-wide significance: two for total cholesterol (FN1 and SAMM50), two for HDL cholesterol (LOC100996634 and COPB1) and one for LDL cholesterol (LINC00324/CTC1/PFAS). The top meta-analysis signals were found to be enriched for SNPs associated with gene expression in a tissue-specific fashion, suggesting an enrichment of tissue-specific function in lipid-associated loci.

Association of polymorphisms within the transforming growth factor-β1 gene with diabetic nephropathy and serum cholesterol and triglyceride concentrations.

Aim:  The TGF‐β gene participates in the development of chronic kidney disease. We investigated whether the 869 T > C, 915 G > C and −800 G > A polymorphisms of TGF‐β1 are associated with diabetic nephropathy (DN).

Allele frequency distribution of CYP2C9*2 and CYP2C9*3 polymorphisms in six Mexican populations

Allele frequency differences of functional CYP2C9 polymorphisms are responsible for some of the variation in drug response observed in human populations. The most relevant CYP2C9 functional variants are CYP2C9*2 (rs1799853) and CYP2C9 3 (rs1057910). These polymorphisms show variation in allele frequencies among different population groups. The present study aimed to analyze these polymorphisms in 947 Mexican-Mestizo from Mexico City and 483 individuals from five indigenous Mexican populations: Nahua, Teenek, Tarahumara, Purepecha and Huichol. The CYP2C9*2 allele frequencies in the Mestizo, Nahua and Teenek populations were 0.051, 0.007 and 0.005, respectively. As for CYP2C9 3, the allelic frequencies in the Mestizo, Nahua and Teenek populations were 0.04, 0.005 and 0.005, respectively. The CYP2C9 2 and CYP2C9 3 alleles were not observed in the Tarahumara, Purepecha and Huichol populations. These findings are in agreement with previous studies reporting very low allele frequencies for these polymorphisms in American Indigenous populations.

DD genotype of angiotensin-converting enzyme in type 2 diabetes mellitus with renal disease in Mexican Mestizos.

Aim:  The DD genotype of angiotensin‐converting enzyme (ACE) has been suggested as a major contributor of diabetic nephropathy in several populations. The purpose of the present study was to determine whether micro/macroalbuminuria is associated with ACE insertion/deletion (I/D) polymorphism in Mexican Mestizos with type 2 diabetes mellitus.

SOD2 gene Val16Ala polymorphism is associated with macroalbuminuria in Mexican Type 2 Diabetes patients: a comparative study and meta-analysis

BackgroundSeveral studies in type 2 diabetes patients have shown significant associations between the SOD2 gene Val16Ala polymorphism and albuminuria, but this association has not been explored in the Mexican population.MethodsWe evaluated the association between the SOD2 gene Val16Ala polymorphism (rs4880) and macroalbuminuria in a sample of 994 unrelated Mexican type 2 diabetes patients. The study included 119 subjects with urinary albumin >300 mg/dL and 875 subjects with urinary albumin ≤ 30 mg/dL. Genotyping of the SOD2 gene Val16Ala SNP was carried out with Real-Time Polymerase Chain Reaction (RT-PCR).ResultsThe frequency of the TT genotype was 6.7% higher in participants with macroalbuminuria than in the normoalbuminuria group (16.8% vs. 10.1%). Using a logistic regression analysis, we observed that individuals with the CC genotype had significantly lower risks of macroalbuminuria than those with the TT genotype (OR=0.42, p=0.034). We carried out a meta-analysis combining our data with data from four previous studies and estimated an odds ratio (95% CI) for the C allele (with respect to the reference T allele) of 0.65 (0.52-0.80, p<0.001).ConclusionsA significant association was found between the SOD2 Val16Ala polymorphism and macroalbuminuria in a sample of Mexican type 2 diabetes patients.

Association of β1 and β3 adrenergic receptors gene polymorphisms with insulin resistance and high lipid profiles related to type 2 diabetes and metabolic syndrome

BACKGROUND Among the diverse genes associated to type 2 diabetes (T2D), the β-adrenergic receptors are an excellent candidate to study in Mexican population. The objective of this work was to analyze the association of polymorphisms in ADRB1 (rs1801253) (Arg389Gly) and ADRB3 (Trp64Arg) genes with T2D and metabolic syndrome (MS). METHODS We studied 445 MS patients, 502 with T2D and 552 healthy controls. Anthropometric features and complete biochemical profile were evaluated, and Arg389Gly and Trp64Arg SNPs were determined by TaqMan assays. Data analysis was adjusted by African, Caucasian and Amerindian ancestral percentage. RESULTS The variant Arg389Gly of ADRB1 was statistically associated with an increase of LDL levels (P < 0.008), and the variant ADRB3 Trp64Arg was associated to larger HOMA-IR (P < 0.018) and with an increase of insulin levels (P < 0.001). A multiple logistic regression analysis was made in three grouping models: For ADRB3 in the codominant model Trp/Arg genotype, there was an OR of 1.53 (1.09-2.13, P < 0.003) which was increased up to OR 2.99 (1.44-6.22, P < 0.003) for the Arg/Arg genotype. Similar risk association was found under the dominant model Trp/Arg-Arg/Arg genotype with OR 1.67 (1.21-2.30; P < 0.002). In the recessive model (Arg/Arg genotype), there was also a high association OR 2.56 (1.24-5.26, P < 0.01). CONCLUSIONS The ADRB3 Trp64Arg variant is a susceptibility gene polymorphism for T2D and the ADRB1 Gly389Arg for lipid metabolism disruption. These results show that these variants are potential biomarkers for predicting metabolic alterations and evolution in diabetic and metabolic syndrome patients.

Evaluation of the imputation performance of the program IMPUTE in an admixed sample from Mexico City using several model designs

BackgroundWe explored the imputation performance of the program IMPUTE in an admixed sample from Mexico City. The following issues were evaluated: (a) the impact of different reference panels (HapMap vs. 1000 Genomes) on imputation; (b) potential differences in imputation performance between single-step vs. two-step (phasing and imputation) approaches; (c) the effect of different posterior genotype probability thresholds on imputation performance and (d) imputation performance in common vs. rare markers.MethodsThe sample from Mexico City comprised 1,310 individuals genotyped with the Affymetrix 5.0 array. We randomly masked 5% of the markers directly genotyped on chromosome 12 (n = 1,046) and compared the imputed genotypes with the microarray genotype calls. Imputation was carried out with the program IMPUTE. The concordance rates between the imputed and observed genotypes were used as a measure of imputation accuracy and the proportion of non-missing genotypes as a measure of imputation efficacy.ResultsThe single-step imputation approach produced slightly higher concordance rates than the two-step strategy (99.1% vs. 98.4% when using the HapMap phase II combined panel), but at the expense of a lower proportion of non-missing genotypes (85.5% vs. 90.1%). The 1,000 Genomes reference sample produced similar concordance rates to the HapMap phase II panel (98.4% for both datasets, using the two-step strategy). However, the 1000 Genomes reference sample increased substantially the proportion of non-missing genotypes (94.7% vs. 90.1%). Rare variants (<1%) had lower imputation accuracy and efficacy than common markers.ConclusionsThe program IMPUTE had an excellent imputation performance for common alleles in an admixed sample from Mexico City, which has primarily Native American (62%) and European (33%) contributions. Genotype concordances were higher than 98.4% using all the imputation strategies, in spite of the fact that no Native American samples are present in the HapMap and 1000 Genomes reference panels. The best balance of imputation accuracy and efficiency was obtained with the 1,000 Genomes panel. Rare variants were not captured effectively by any of the available panels, emphasizing the need to be cautious in the interpretation of association results for imputed rare variants.

Polymorphisms in the LPL and CETP Genes and Haplotype in the ESR1 Gene Are Associated with Metabolic Syndrome in Women from Southwestern Mexico.

Metabolic syndrome (MetS) is a combination of metabolic disorders associated with an increased risk for cardiovascular disease (CVD). Studies in women reported associations between polymorphisms in ESR1, LPL and CETP genes and MetS. Our aim was to evaluate the association between variants in ESR1, LPL and CETP genes with MetS and its components. Four hundred and eighty women were analyzed, anthropometric features and biochemical profiles were evaluated, and genotyping was performed by real-time PCR. We found an association with elevated glucose levels (odds ratio (OR) = 2.9; p = 0.013) in carrying the AA genotype of rs1884051 in the ESR1 gene compared with the GG genotype, and the CC genotype of rs328 in the LPL gene was associated with MetS compared to the CG or GG genotype (OR = 2.8; p = 0.04). Moreover, the GA genotype of rs708272 in the CETP gene is associated with MetS compared to the GG or AA genotype (OR = 1.8; p = 0.006). In addition the ACTCCG haplotype in the ESR1 gene is associated with a decrease in the risk of MetS (OR = 0.02; p < 0.001). In conclusion, our results show the involvement of the variants of ESR1, LPL and CETP genes in metabolic events related to MetS or some of its features.

Frequency of the Serological Reactivity Against the Caprine Arthritis Encephalitis Lentivirus gp135 in Children Who Consume Goat Milk

BACKGROUND Caprine arthritis encephalitis virus (CAEV) is a retrovirus belonging to the lentivirus genus that also includes the human immunodeficiency virus (HIV). CAEV may be transmitted to humans by goat milk consumption. It has been suggested that CAEV may also be involved in the immunological protection process against HIV, but this has not been demonstrated. Here we identified serological reactivity against CAEV gp135 in children who consumed goat milk. METHODS Thirty sera samples from children (males between 6 and 16 years of age) who regularly consumed goat milk and a negative control of 30 serum samples from children (males between 6 and 12 years) with no previous contact with goats or goat dairy products were used. All sera were tested by Western blot against CAEV antigens. RESULTS There were 18/30 serum samples from goat milk consumers that were reactive to CAEV gp135, and one reacted against gp50 simultaneously; none of the 30 serum samples from nonconsumers of goat dairy products reacted to viral proteins. CONCLUSIONS These results showed that the positive response to gp135 may be the result of a repetitive stimulation without viral replication or the result of CAEV replication in humans. CAEV gp135 is codified by the env gene located on the viral particle surface as well as gp50. Moreover, there are similarities between CAEV gp135 and HIV-1 gp120, so there is a possibility that CAEV replicates in humans and may participate in immunological cross-phenomena, but this should be further studied.