Gene frequencies and admixture estimates in the state of Puebla, Mexico

Osteopontin Gene Polymorphisms Are Associated with Cardiovascular Risk Factors in Patients with Premature Coronary Artery Disease

Osteopontin (OPN) is considered a clinical predictor of cardiovascular disease. We aimed to evaluate the association of the OPN gene polymorphisms rs2728127 and rs11730582 with the development of premature coronary artery disease (pCAD), cardiovascular risk factors, and cardiometabolic parameters. We evaluated 1142 patients with pCAD and 1073 controls. Both polymorphisms were determined by Taqman assays. Similar allele and genotype frequencies were observed in both groups; additionally, an association of these polymorphisms with CAD and cardiometabolic parameters was observed in both groups. In patients with pCAD, the rs11730582 was associated with a high risk of hypoadiponectinemia (OR = 1.300, P _additive = 0.003), low risk of hypertension (OR = 0.709, P _{codominant 1} = 0.030), and low risk of having high non-HDL cholesterol (OR = 0.637, P _additive = 0.038). In the control group, the rs2728127 was associated with a low risk of fatty liver (OR = 0.766, P _additive = 0.038); while the rs11730582 was associated with a low risk of hypoadiponectinemia (OR = 0.728, P _dominant = 0.022), and risk of having elevated apolipoprotein B (OR = 1.400, P _dominant = 0.031). Our results suggest that in Mexican individuals, the rs11730582 and rs2728127 OPN gene polymorphisms are associated with some abnormal metabolic variables in patients with pCAD and controls.

The rs46522 Polymorphism of the Ubiquitin-Conjugating Enzyme E2Z Gene Is Associated with Abnormal Metabolic Parameters in Patients with Myocardial Infarction: The Genetics of Atherosclerosis Disease Mexican Study

The participation of ubiquitin-conjugating enzyme E2Z (UBE2Z) in atherosclerosis has been reported. We aimed to evaluate the association of the rs46522 polymorphism of the UBE2Z gene with myocardial infarction (MI) and other clinical and metabolic components in the Mexican population. A total of 2128 individuals (1023 patients with MI and 1105 healthy controls) were included. rs46522 was genotyped using the 5' exonuclease TaqMan genotyping assay. A similar polymorphism distribution was observed between patients and healthy controls. The association between rs46522 polymorphism and cardiometabolic parameters was evaluated separately in the two groups. In the control group, rs46522 polymorphism was associated with increased risk of developing low-density lipoprotein cholesterol ≥130 mg/dL (odds ratio [OR] = 1.249, p_additive = 0.018; OR = 1.479, p_recessive = 0.015; OR = 1.589, p_{codominant 2} = 0.013). On the other hand, in MI patients, it was observed that rs46522 polymorphism was associated with an increased risk of developing high levels of alanine transaminase (OR = 1.297, p_heterozygote = 0.043) and aspartate transaminase (OR = 1.453, p_dominant = 0.009; OR = 1.592, p_heterozygote = 0.001; OR = 1.632, p_{codominant 1} = 0.001). Our results suggest that the UBE2Z gene rs46522 polymorphism is associated with abnormal metabolic parameters in Mexican patients with MI.

Interleukin 27 polymorphisms, their association with insulin resistance and their contribution to subclinical atherosclerosis. The GEA Mexican study

Our previous data suggest that the heterodimeric interleukin-27 (IL-27) could participate in the developing of insulin resistance (IR). Our aim was to assess the participation of IL-27p28 gene single nucleotide polymorphisms (SNPs) as markers for IR, subclinical atherosclerosis (SA) and cardiovascular risk factors in a Mexican population. Five IL-27p28 SNPs (rs153109, rs40837, rs17855750, rs26528 and rs181206) were genotyped in 856 individuals with IR and 644 participants without IR. Under inheritance models adjusted for confounding factors, the rs153109A (0.78[0.64-0.94] P_additive = 0.008, 0.58[0.41-0.82] P_recessive = 0.002, 0.57[0.38-0.83] P_codominant2 = 0.004), rs26528T (0.78[0.64-0.94] P_additive = 0.008, 0.61[0.43-0.88] P_recessive = 0.007, 0.57[0.38-0.84] P_codominant2 = 0.004) and rs40837A (0.76[0.63-0.92] P_additive = 0.004; 0.60[0.42-0.86] P_recessive = 0.005; 0.54[0.37-0.80] P_codominant2 = 0.002) alleles were related with a decreased risk of IR. Moreover, AAATA haplotype that contains the protector alleles was related with 17% lower risk of presenting IR (0.83 [0.71-0.98], P = 0.023). After adjusting for potential confounding variables, IL-27p28 SNPs were not associated with SA. However, some SNPs were associated with hypertension (rs26528 and rs40837) and increased total abdominal fat (rs17855750) in non-IR individuals, whereas in IR subjects we observed an association of rs26528 and rs40837 with hypoadiponectinemia. Our evidence suggests that rs40837A, rs153109A, and rs26528T alleles could be envisaged as protective markers for IR. Some polymorphisms showed an association with hypertension, low adiponectin levels, and increased total abdominal fat.

Blood Groups Distribution and Gene Diversity of the ABO and Rh (D) Loci in the Mexican Population

Objective

To determine the frequency and distribution of ABO and Rh (D) antigens and, additionally, investigate gene diversity and the structure of Mexican populations.

Materials and Methods

Blood groups were tested in 271,164 subjects from 2014 to 2016. The ABO blood group was determined by agglutination using the antibodies anti-A, Anti-B, and Anti-D for the Rh factor, respectively.

Results

The overall distribution of ABO and Rh (D) groups in the population studied was as follows: O: 61.82%; A: 27.44%; B: 8.93%; and AB: 1.81%. For the Rh group, 95.58% of people were Rh (D), and 4.42% were Rh (d). Different distributions of blood groups across regions were found; additionally, genetic analysis revealed that the I^O and I^D allele showed an increasing trend from the north to the center, while the I^A and I^d allele tended to increase from the center to the north. Also, we found more gene diversity in both loci in the north compared with the center, suggesting population structure in Mexico.

Conclusion

This work could help health institutions to identify where they can obtain blood products necessary for medical interventions. Moreover, this piece of information contributes to the knowledge of the genetic structure of the Mexican populations which could have significant implications in different fields of biomedicine.

Interleukin-27 polymorphisms are associated with premature coronary artery disease and metabolic parameters in the Mexican population: the genetics of atherosclerotic disease (GEA) Mexican study

Several studies suggest an important role of Interleukin-27 in the development of atherosclerosis. The aim of this study was to establish whether the IL-27p28 gene polymorphisms are associated with premature coronary artery disease and/or other cardiovascular risk factors. Four IL-27p28 gene polymorphisms were selected and genotyped in 1162 premature coronary artery disease cases and 1107 controls. rs26528 T and rs40837 A alleles were significantly associated with a lower risk of premature coronary artery disease under different inheritance models (Pdominant = 0.046; Pover-dominant = 0.002; Pco-dominant1 = 0.007 for rs26528T; Pover-dominant = 0.008 and Pco-dominant1 = 0.031 for rs40837). The rs40837 A allele was also associated with a lower risk of insulin resistance, in cases (Pover-dominant = 0.037) and controls (Padditive = 0.008; Pdominant = 0.047; Precessive = 0.014; Pco-dominant2 = 0.006), while the rs26528 T allele was associated with a lower risk of insulin resistance only in the control group (Precessive = 0.016; Pco-dominant2 = 0.021). Interleukin-27 plasma levels were measured in 450 controls and 450 cases, and were significantly higher in cases compared to controls (P = 0.004). However, Interleukin-27 plasma levels were not associated with IL-27p28 polymorphisms. Luciferase assays showed that co-transfection of the rs40837 A allele and miR-379-5p significantly decreased luciferase gene expression. Our study shows for the first time, that IL-27p28 gene polymorphisms are associated with premature coronary artery disease and with some metabolic parameters. The rs40837 A allele in presence of miR-379-5p significantly decreased luciferase gene expression.

Correlation of geographic distributions of haptoglobin alleles with prevalence of multiple sclerosis (MS) - a narrative literature review

We have proposed that the myelin damage observed in multiple sclerosis (MS) may be partly mediated through the long-term release and degradation of extracellular hemoglobin (Hb) and the products of its oxidative degradation [Cellular and Molecular Life Sciences, 71, 1789-1798, 2014]. The protein haptoglobin (Hpt) binds extracellular Hb as a first line of defense, and can serve as a vascular antioxidant. Humans have two different Hpt alleles: Hpt1 and Hpt2, giving either homozygous Hpt1-1 or Hpt2-2 phenotypes, or a heterozygous Hpt1-2 phenotype. We questioned whether those geographic regions with higher frequency of the Hpt2 allele (conversely, lower frequency of Hpt1 allele) would correlate with an increased incidence of MS, because different Hpt phenotypes will have variable anti-oxidative potentials in protecting myelin from damage inflicted by extracellular Hb and its degradation products. To test this hypothesis, we undertook a systematic analysis of the literature on reported geographic distributions of Hpt alleles to compare them with data reported in the World Health Organization Atlas of worldwide MS prevalence. We found the frequency of the Hpt1 allele to be low in European and North American countries with a high prevalence of MS, consistent with our hypothesis. However, this correlation was not observed in China and India, countries with the lowest Hpt1 frequencies, yet low reported prevalence of MS. Nevertheless, this work shows the need for continued refinement of geographic patterns of MS prevalence, including data on ethnic or racial origin, and for new clinical studies to probe the observed correlation and evaluate Hpt phenotype as a predictor of disease variability and progression, severity, and/or comorbidity with cardiovascular disorders.

The rs7044343 Polymorphism of the Interleukin 33 Gene Is Associated with Decreased Risk of Developing Premature Coronary Artery Disease and Central Obesity, and Could Be Involved in Regulating the Production of IL-33

AIM

The effect of interleukin 33 (IL-33) in the inflammatory process generates significant interest in the potential significance of IL-33 as a biomarker for coronary artery disease (CAD). Here, our objective was to analyze whether IL-33 gene polymorphisms are associated with premature CAD in a case-control association study.

METHODS

Four IL-33 polymorphisms (rs7848215, rs16924144, rs16924159 and rs7044343) were genotyped by 5' exonuclease TaqMan assays in 1095 patients with premature CAD and 1118 controls.

RESULTS

The rs7044343 T allele was significantly associated with a diminished risk of premature CAD (OR = 0.81, 95% CI: 0.69-0.97, Pdom = 0.020; OR = 0.85, 95% CI: 0.75-0.96, Padd = 0.019) and central obesity (OR = 0.74, 95% CI: 0.58-0.93, Pdom = 0.0007), respectively. When patients were divided into groups with and without type 2 diabetes mellitus (T2DM), the rs7044343 T allele was associated with a reduced risk of premature CAD in patients without (OR = 0.85, 95% CI: 0.73-0.99, Padd = 0.038) and with T2DM (OR = 0.61, 95% CI: 0.38-0.97, Pdom = 0.039; OR = 0.69, 95% CI: 0.49-0.97, Padd = 0.035). In order to establish the functional effect of the rs7044343 polymorphism, the production of IL-33 was determined in monocytes of selected individuals. Monocytes from individuals with rs7044343 CC genotype produced higher levels of IL-33 than monocytes from individuals with other genotypes.

CONCLUSION

The results suggest that the IL-33 rs7044343 T allele could be a susceptibility marker for premature CAD and central obesity. The rs7044343 polymorphism could be involved in regulating the production of IL-33.

Receptor-interacting protein 2 (RIP2) gene polymorphisms are associated with increased risk of subclinical atherosclerosis and clinical and metabolic parameters. The Genetics of Atherosclerotic Disease (GEA) Mexican study

The receptor-interacting protein 2 (Rip2) is a serine/threonine kinase involved in multiple nuclear factor-κB (NFκB) activation pathways and is a key regulator of cellular lipid metabolism and cardiovascular disease. The aim of the present study was to evaluate the role of RIP2 gene polymorphisms as susceptibility markers for subclinical atherosclerosis (SA). Using an informatics analysis, four RIP2 gene polymorphisms with predicted functional effects (rs2293808, rs43133, rs431264, and rs16900627) were selected. The polymorphisms were genotyped in 405 individuals with SA (calcium score>0 assessed by computed tomography) and 1099 controls (calcium score=0). Clinical, anthropometric, tomographic and biochemical traits were measured. The association between the RIP2 polymorphisms and SA was evaluated using logistic regression analyses. Pair wise linkage disequilibrium (LD, D') estimations between polymorphisms and haplotype reconstruction were performed with Haploview version 4:1. Under different models adjusted by age, gender, body mass index, hypertension, diabetes mellitus, smoking habit, total cholesterol, HDL-cholesterol, LDL-cholesterol and triglyceride levels, rs43133 (OR=1.43, 95% CI: 1.05-1.94, P=0.022), and rs16900627 (OR=1.59, 95% CI: 1.00-2.54, P_dom=0.048 and OR=1.60, 95% CI: 1.05-2.54, P_add=0.028) were associated with increased risk of developing SA. Moreover, rs2293808, and rs431264 were associated with clinical or metabolic parameters in SA individuals and in healthy controls. The four polymorphisms were in high linkage disequilibrium and the GAAG haplotype was associated with increased risk of developing SA (OR=1.47, P=0.027). This study shows for the first time, that RIP2 polymorphisms are associated with increased risk of SA and with some clinical and metabolic parameters.

Association of the I148M/PNPLA3 (rs738409) polymorphism with premature coronary artery disease, fatty liver, and insulin resistance in type 2 diabetic patients and healthy controls. The GEA study

The aim of this study was to evaluate the potential use of the I148M/PNPLA3 (rs738409) gene polymorphism as a susceptibility marker for premature coronary artery disease (pCAD) and/or cardiovascular risk factors in Mexican type 2 diabetes mellitus patients (T2DM). The polymorphism was genotyped by 5' exonuclease TaqMan assays in a group of 2572 subjects (1103 with pCAD and 1469 healthy controls) belonging to the Genetics of Atherosclerotic Disease (GEA) Mexican Study. Anthropometric and biochemical measurements were performed in all individuals. The association between the I148M/PNPLA3 (rs738409) gene polymorphism with pCAD and other metabolic and cardiovascular risk factors was evaluated using logistic regression analysis under different statistical approaches including dominant, recessive, heterozygous, additive, and co-dominant models. The polymorphism was not associated with pCAD in the whole group of participants, however, when patients and controls were divided into those with and without T2DM, under additive model, the polymorphism was associated with the presence of pCAD only in patients with T2DM (OR=1.20, 95% CI: 1.01-1.42, P_add=0.042). On the other hand, under several models adjusted for age, gender, body mass index and T2DM, the polymorphism was associated with increased risk of fatty liver and elevated levels of alanine transaminase (ALT) in the whole group of pCAD patients and controls. In the control group, the polymorphism was associated with insulin resistance and coronary artery calcification (CAC) score≥10 under several models. The results suggest that the I148M/PNPLA3 (rs738409) polymorphism is associated with the presence of pCAD in T2DM patients and with some cardiometabolic parameters. The association detected with CAC in the control group indicates that this polymorphism could be a marker for subclinical atherosclerosis.

Monocyte chemoattractant protein-1 gene (MCP-1) polymorphisms are associated with risk of premature coronary artery disease in Mexican patients from the Genetics of Atherosclerotic Disease (GEA) study

The CC chemokine monocyte chemoattractant protein (MCP)-1/CCL2 is involved in the formation, progression, and destabilization of atheromatous plaques and plays an essential role in postinfarction remodeling. The aim of the present study was to evaluate the role of MCP-1 gene polymorphisms as susceptibility markers for premature coronary artery disease (CAD) and cardiovascular risk factors in the Mexican population. Four MCP-1 gene polymorphisms (rs1024611, rs2857654, rs3760396, and rs1024610) were genotyped by 5' exonuclease TaqMan assays in a group of 1072 patients with premature CAD, and 1082 healthy unrelated controls (with negative calcium score by computed tomography) seeking for associations with premature CAD and other metabolic and cardiovascular risk factors using logistic regression analyses. MCP-1 polymorphism frequencies were similar in premature CAD patients and healthy controls. When the analysis included only those premature CAD patients without type 2 diabetes mellitus (T2DM), the rs1024610 polymorphism was associated with increased risk of developing premature CAD under dominant and additive models adjusted by age and gender (OR=1.33, Pdom=0.040 and OR=1.34, Padd=0.027). The effect of the MCP-1 polymorphisms on various metabolic cardiovascular risk factors and metabolic parameters was explored separately in controls, and premature CAD. In this analysis adjusted by age and gender, the rs3760396 CC genotype was associated with low levels of gamma-glutamyl transpeptidase (P=0.002), whereas, the rs1024610 TT genotype was associated with decreased risk of T2DM (P=0.035) in premature CAD patients. One haplotype (CATG) was associated with increased risk of developing premature CAD (OR=1.44, P=0.0019). In summary, in our study, the rs1024610 polymorphism was associated with increased risk of developing premature CAD only in those patients without T2DM. The four MCP-1 polymorphisms were in high linkage disequilibrium and one haplotype was significantly associated with risk of developing premature CAD.

Interleukin-17A gene haplotypes are associated with risk of premature coronary artery disease in Mexican patients from the Genetics of Atherosclerotic Disease (GEA) study

Aim

The role of interleukin 17A (IL-17A) in the inflammatory process has caused interest in the potential significance of IL-17A as a biomarker for coronary artery disease (CAD). The aim of the present study was to evaluate the role of IL-17A gene polymorphisms as susceptibility markers for CAD in the Mexican population.

Methods

Four IL-17A gene polymorphisms (rs8193036, rs3819024, rs2275913 and rs8193037) were genotyped by 5’ exonuclease TaqMan assays in a group of 900 patients with premature CAD and 667 healthy controls (with negative calcium score by computed tomography), seeking associations with CAD and other metabolic and cardiovascular risk factors using logistic regression analyses.

Results

No single IL-17A polymorphism was associated with premature CAD, however two haplotypes (CAGG and TAGA) were significantly associated with increased risk of premature CAD (OR = 1.35, 95% CI: 1.00–1.84, P = 0.018 and OR = 2.09, 95% CI: 1.16–3.76, P = 0.003, respectively). Moreover, rs3819024 was associated with increased levels of visceral abdominal fat (P = 0.002) and rs8193036 was significantly associated with risk of central obesity (P = 0.020), hypertriglyceridemia (P = 0.027), and metabolic syndrome (P = 0.027) in the premature CAD group, under dominant models adjusted by age, gender, BMI, smoking history, alcohol consumption, and treatment.

Conclusion

The results suggest that IL-17A haplotypes are involved in the risk of developing premature CAD and some IL-17A polymorphisms are associated with cardiovascular risk factors in Mexican individuals with premature CAD.

G6PD deficiency in Latin America: systematic review on prevalence and variants

Plasmodium vivax radical cure requires the use of primaquine (PQ), a drug that induces haemolysis in glucose-6-phosphate dehydrogenase deficient (G6PDd) individuals, which further hampers malaria control efforts. The aim of this work was to study the G6PDd prevalence and variants in Latin America (LA) and the Caribbean region. A systematic search of the published literature was undertaken in August 2013. Bibliographies of manuscripts were also searched and additional references were identified. Low prevalence rates of G6PDd were documented in Argentina, Bolivia, Mexico, Peru and Uruguay, but studies from Curaçao, Ecuador, Jamaica, Saint Lucia, Suriname and Trinidad, as well as some surveys carried out in areas of Brazil, Colombia and Cuba, have shown a high prevalence (> 10%) of G6PDd. The G6PD A-202A mutation was the variant most broadly distributed across LA and was identified in 81.1% of the deficient individuals surveyed. G6PDd is a frequent phenomenon in LA, although certain Amerindian populations may not be affected, suggesting that PQ could be safely used in these specific populations. Population-wide use of PQ as part of malaria elimination strategies in LA cannot be supported unless a rapid, accurate and field-deployable G6PDd diagnostic test is made available.

Haplotypes of the angiotensin-converting enzyme (ACE) gene are associated with coronary artery disease but not with restenosis after coronary stenting

The aim of the present study was to establish the role of ACE gene polymorphisms in the risk of developing in-stent restenosis and/or coronary artery disease (CAD). Eight ACE gene polymorphisms were genotyped by 5' exonuclease TaqMan genotyping assays in 236 patients with CAD who underwent coronary artery stenting. Basal and procedure coronary angiographies were analyzed searching for angiographic predictors of restenosis and follow-up angiography was analyzed looking for binary restenosis. A group of 455 individuals without clinical and familial antecedents of cardiovascular diseases were included as controls. Haplotypes were constructed after linkage disequilibrium analysis. Distribution of ACE polymorphisms was similar in patients with and without restenosis. Similar results were observed when the analysis was made comparing the whole group of patients (with and without restenosis) and healthy controls. Six out of eight polymorphisms were in high linkage disequilibrium and were included in five haplotypes (AAAGCA, GGGATG, GAGATG, AGAGCA and AAGACA). The distribution of these haplotypes was similar in patients with and without restenosis. However, CAD patients showed an increased frequency of the AAAGCA haplotype (OR=1.31, 95% CI: 1.04-1.66, P=0.018) and decreased frequencies of GAGATG (OR=0.47, 95% CI: 0.25-0.88, P=0.011) and AGAGCA (OR=0.15, 95% CI: 0.02-0.65, P=0.002) haplotypes when compared to healthy controls. Haplotypes of the ACE gene could be a genetic factor related to coronary artery disease in the Mexican individuals, but do not support its role as a risk factor for developing restenosis after coronary stenting.

IL-24 gene polymorphisms are associated with cardiometabolic parameters and cardiovascular risk factors but not with premature coronary artery disease: the genetics of atherosclerotic disease Mexican study

Coronary artery disease (CAD) is a multifactorial and polygenic disorder that results from an excessive inflammatory response. We analyzed whether interleukin-24 (IL-24) gene polymorphisms are associated with premature CAD in a case-control association study. Four polymorphisms (rs1150253, rs1150256, rs1150258, and rs3762344) of the IL-24 gene were analyzed by 5' exonuclease TaqMan genotyping assays in a group of 952 patients with premature CAD, 284 individuals with subclinical atherosclerosis (SA), and 912 controls. The studied polymorphisms were not associated with the risk of premature CAD or SA (P>0.05). Under dominant models adjusted for age, sex, body mass index, and medication, the polymorphisms were associated with cardiometabolic parameters and cardiovascular risk factors. Three polymorphisms (rs1150253, rs1150256, and rs3762344) were associated with hypertension and increased levels of systolic blood pressure in controls. In SA, 2 polymorphisms (rs1150256 and rs3762344) were associated with type 2 diabetes mellitus, gamma-glutamyl transpeptidase (GGT), and alkaline phosphatase, whereas rs1150253 was associated with GGT and type 2 diabetes mellitus and rs1150258 with GGT and alkaline phosphatase. In premature CAD, the 4 polymorphisms were associated with total cholesterol >200 mg/dL, low-density lipoprotein cholesterol (LDL-C), and GGT, whereas rs1150256 was associated also with ApoA. On the other hand, rs1150258 was associated with ApoA, LDL-C >100 mg/dL, and apoB/apoA ratio, and rs3762344 with ApoA, apoB/apoA ratio, LDL-C >100 mg/dL, and total cholesterol. On the basis of single-nucleotide polymorphism functional prediction software, rs1150253 and rs1150258 polymorphisms seem to be functional. The 4 studied polymorphisms were in linkage disequilibrium and had a similar haplotype distribution in patients and controls. Our study demonstrates the association of IL-24 polymorphisms with metabolic and cardiovascular risk factors in individuals with premature CAD, SA, and controls.

The matrix metalloproteinase 2-1575 gene polymorphism is associated with the risk of developing myocardial infarction in Mexican patients

AIM

Was to evaluate the role of seven matrix metalloproteinase (MMP) polymorphisms in the genetic susceptibility to develop myocardial infarction in Mexican individuals.

METHODS

Seven polymorphisms in the MMP genes were genotyped by 5' exonuclease TaqMan genotyping assays in 300 patients with myocardial infarction and 300 healthy unrelated controls.

RESULTS

A similar distribution of MMP2-1306 (rs243865), MMP2-790 (rs243864), MMP2-735 (rs22850553), MMP7-153(rs11568819), MMP7-181(rs11568818), and MMP12-82(rs2276109) polymorphisms was observed in both studied groups. On the other hand, patients showed increased frequencies of MMP2-1575 A allele and AA genotype when compared to controls (pC= 0.001; OR= 1.58 and pC= 0.036; OR= 2.37, respectively). According to the dominant model, individuals with AG+AA genotypes had a 1.65-fold increased risk of developing the disease (p= 0.002). After adjusting for known risk factors, we found a significant contribution of gender, BMI, smoking habit, diabetes mellitus, and hypertension to the inheritance model. In this analysis, individuals with the-1575 AA genotype had a 4.23-fold increased risk of developing MI (p= 0.003). On the other hand, an association of the MMP12-82 polymorphism with the extent of coronary artery disease (CAD) was observed. In our study, it was possible to distinguish two risk haplotypes and one protective haplotype for this disease in the MMP2 gene.

CONCLUSIONS

The results suggest that the MMP2-1575 (rs243866) gene polymorphism could be involved in the risk of developing myocardial infarction in Mexican individuals.

The IL1B-511 Polymorphism (rs16944 AA Genotype) Is Increased in Aspirin-Exacerbated Respiratory Disease in Mexican Population

Aspirin exacerbated respiratory disease (AERD) is characterized by chronic hyperplastic rhinosinusitis, nasal polyposis, asthma, and aspirin sensitivity. The mechanisms which produce these manifestations of intolerance are not fully defined, current research focuses on cyclooxygenase 1 (COX-1) inhibition, metabolism of arachidonic acid, and the COX pathway to the lipoxygenase (LO) route, inducing increased synthesis of leukotrienes (LT). The biological plausibility of this model has led to the search for polymorphisms in genes responsible for proinflammatory cytokines synthesis, such as IL1B and IL8. We performed a genetic association study between IL8-251 (rs4073) and IL1B-511 (rs16944) polymorphisms in AERD, aspirin-tolerant asthma (ATA), and healthy control subjects. Using allelic discrimination by real-time PCR, we found statistically nonsignificant associations between AERD, ATA, and healthy control subjects for the GG and GA genotypes of IL1B (rs16944). Interestingly, the AA genotype showed an increased frequency in the AERD patients versus the ATA group (GF = 0.19 versus 0.07, p = 0.018, OR 2.98, and 95% CI 1.17–7.82). This is the first observation that IL1B polymorphisms are involved in AERD. Thus, future studies must investigate whether interleukin-1β is released in the airways of AERD patients and whether it relates to genetic polymorphisms in the IL1B gene.

Large scale mitochondrial sequencing in Mexican Americans suggests a reappraisal of Native American origins

Background

The Asian origin of Native Americans is largely accepted. However uncertainties persist regarding the source population(s) within Asia, the divergence and arrival time(s) of the founder groups, the number of expansion events, and migration routes into the New World. mtDNA data, presented over the past two decades, have been used to suggest a single-migration model for which the Beringian land mass plays an important role.

Results

In our analysis of 568 mitochondrial genomes, the coalescent age estimates of shared roots between Native American and Siberian-Asian lineages, calculated using two different mutation rates, are A4 (27.5 ± 6.8 kya/22.7 ± 7.4 kya), C1 (21.4 ± 2.7 kya/16.4 ± 1.5 kya), C4 (21.0 ± 4.6 kya/20.0 ± 6.4 kya), and D4e1 (24.1 ± 9.0 kya/17.9 ± 10.0 kya). The coalescent age estimates of pan-American haplogroups calculated using the same two mutation rates (A2:19.5 ± 1.3 kya/16.1 ± 1.5 kya, B2:20.8 ± 2.0 kya/18.1 ± 2.4 kya, C1:21.4 ± 2.7 kya/16.4 ± 1.5 kya and D1:17.2 ± 2.0 kya/14.9 ± 2.2 kya) and estimates of population expansions within America (~21-16 kya), support the pre-Clovis occupation of the New World. The phylogeography of sublineages within American haplogroups A2, B2, D1 and the C1b, C1c andC1d subhaplogroups of C1 are complex and largely specific to geographical North, Central and South America. However some sub-branches (B2b, C1b, C1c, C1d and D1f) already existed in American founder haplogroups before expansion into the America.

Conclusions

Our results suggest that Native American founders diverged from their Siberian-Asian progenitors sometime during the last glacial maximum (LGM) and expanded into America soon after the LGM peak (~20-16 kya). The phylogeography of haplogroup C1 suggest that this American founder haplogroup differentiated in Siberia-Asia. The situation is less clear for haplogroup B2, however haplogroups A2 and D1 may have differentiated soon after the Native American founders divergence. A moderate population bottle neck in American founder populations just before the expansion most plausibly resulted in few founder types in America. The similar estimates of the diversity indices and Bayesian skyline analysis in North America, Central America and South America suggest almost simultaneous (~ 2.0 ky from South to North America) colonization of these geographical regions with rapid population expansion differentiating into more or less regional branches across the pan-American haplogroups.

PSMB8 (LMP7) but not PSMB9 (LMP2) gene polymorphisms are associated to pigeon breeder's hypersensitivity pneumonitis

Hypersensitivity Pneumonitis (HP) is a lung inflammatory disorder caused by inhalation of organic particles by a susceptible host. However, only a small proportion of individuals exposed to HP-associated antigens develop the disease, suggesting that additional host/environmental factors may play a role. We have previously found that genetic susceptibility associated to the major histocompatibility complex (MHC) plays an important role in this disease. The low molecular weight proteosome (LMP, currently named PSMB) genes code for subunits of the proteosome, a multimeric enzymatic complex that degrades proteins into peptides in order to be presented in the MHC class I pathway. We hypothesized that polymorphisms in PSMB8 or PSMB9 genes could be involved in the susceptibility to HP. Thus, in this study we analyzed the polymorphic site at amino acid position 60 (Arg/His) of the fourth exon in the PSMB9 gene and the amino acid position 49 (Gln/Lys) in the second exon of PSMB8 gene in 50 Mexican patients with HP and 50 healthy ethnically matched controls. PSMB typing was performed using polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP). Our results demonstrated that HP patients had a significant increase of the PSMB8 KQ genotype frequency (OR = 7.25, CI = 2.61-21.3; p = 0.000034). No differences were found in the distribution of PSMB9 alleles/genotypes. However, PSMB9-RH/PSMB8 KQ haplotype was significantly increased in HP patients (OR = 6.77, CI = 1.34-65.31, p < 0.02). These findings suggest that PSMB8 KQ genotype could increase the risk to develop hypersensitivity pneumonitis.

No evidence of the human chorionic gonadotropin-beta gene 5 betaV79M polymorphism in Mexican women

Human chorionic gonadotropin (hCG) is a placental hormone essential for the maintenance of pregnancy. Previous studies have shown a G to A transition in exon 3 of the hCGbeta gene 5, which changes the naturally occurring valine to methionine in codon 79. The frequency of this transition varies among different ethnic groups, being high in USA women, and less common, or absent, in various European populations. The purpose of the present study was to determine the frequency of the betaV79M allelic variant of the beta-subunit of hCG in a Mexican population, and to compare this frequency with those found in other ethnic groups. Placental DNA from 161 pregnant Mexican women was genotyped for the betaV79M by polymerase chain reaction (PCR)-restriction fragments length polymorphism analysis. No polymorphic betaV79M alleles were identified in the population studied. The allele and genotypic frequencies of betaV79M polymorphism in Mexican Mestizo women were significantly different from those reported for the US population, but not from five different European populations. In contrast to what has been found in women from the USA, it seems that the hCGbeta V79M polymorphism is absent or extremely rare in Mexican Mestizo women.

Transporter associated with antigen processing (TAP) 1 gene polymorphisms in patients with hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HP) is a lung inflammatory disease caused by the inhalation of a variety of antigens. Previous studies support the role of the major histocompatibility complex (MHC) class II genes in the susceptibility to develop HP. However, the putative role of other MHC loci has not been elucidated. Transporters associated with antigen processing (TAP) genes are located within the MHC class II region and play an important role transporting peptides across the endoplasmic reticulum membrane for MHC class I molecules assembly. The distribution of single nucleotide polymorphisms (SNPs) in TAP1 genes was analyzed in 73 hypersensitivity pneumonitis (HP) patients and 58 normal subjects. We found a significant association of the allele Gly-637 (GGC) (p=0.00004, OR=27.30, CI=3.87-548.04) and the genotypes Asp-637/Gly-637 (p=0.01, OR=16.0, CI=2.19-631.21), Pro-661/Pro-661 (p=0.006, OR=11.30, CI=2.28-75.77) with HP. A significant decrease in the frequency of the allele Pro-661 (CCA) (p=0.008, OR=0.06, CI=0-0.45), the genotype Asp-637/Asp-637 (p=0.01, OR=0.17, 95% CI=0.05-0.58) and the haplotype [Val-333 (GTC), Val-458 (GTG), Gly-637 (GGC), Pro-661 (CCA)] was detected in HP patients compared with controls (p=0.002, OR=0.07, CI=0.0-0.57). These findings suggest that TAP1 gene polymorphisms are related to HP risk, and highlight the importance of the MHC in the development of this disease.

Genetic admixture and diversity estimations in the Mexican Mestizo population from Mexico City using 15 STR polymorphic markers

The 15 AmpFlSTR Identifiler loci D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, vWA, TPOX, D18S51, D5S818 and FGA were analyzed in a sample of 378 unrelated individuals from Mexico City, Mexico. Significant deviations from HW equilibrium in 14/15 STR loci alleles were not detected. The D18S51 locus had the highest power of discrimination (0.970). Genetic admixture estimations revealed a 69% of Amerindian, 26% of European and 5% of African contribution. Comparative analyses between Mexicans and other neighboring populations reveal significant differences in genetic diversity. Our results are important for future comparative genetic studies in different Latin American ethnic groups, particularly Mexican Mestizos and Amerindians. They should also be helpful in genetics, population evolution, forensic and paternity testing.

HLA class I and class II haplotypes in admixed families from several regions of Mexico

We studied HLA class I and class II alleles in 191 Mexican families (381 non-related individuals) to directly obtain the HLA-A/B/DRB1/DQB1 haplotypes and their linkage disequilibrium (LD). The most frequent HLA haplotypes observed were: A*02-B*39-DRB1*04-DQB1*0302, A*02-B*35-DRB1*04-DQB1*0302, A*68-B*39-DRB1*04-DQB1*0302, A*02-B*35-DRB1*08-DQB1*04, A*33-B*1402-DRB1*01-DQB1*05, and A*24-B*35-DRB1*04-DQB1*0302. The four most common haplotypes found by our study involve those previously reported in Amerindian populations. LD analysis of HLA-A-B and HLA-B-DRB1 loci showed significant associations between A29(19)-B44(12), A33(19)-B65(14), A1-B8, A26(19)-B44(12), A24(9)-B61(40), B65(14)-DR1, B8-DR17(3), B44(12)-DR7, B7-DR15(2), and B39(16)-DR4. Also, all DRB1-DQB1 associations showed significant LD values. Admixture estimations using a trihybrid model showed that Mexicans from the State of Sinaloa (Northern Mexico) have a greater proportion of European genetic component compared with Mexicans from the Central area of Mexico, who have a greater percentage of Amerindian genes. Our results are important for future comparative genetic studies of different Mexican ethnic groups with special relevance to disease association and transplantation studies.

Admixture in Mexico City: implications for admixture mapping of type 2 diabetes genetic risk factors

Admixture mapping is a recently developed method for identifying genetic risk factors involved in complex traits or diseases showing prevalence differences between major continental groups. Type 2 diabetes (T2D) is at least twice as prevalent in Native American populations as in populations of European ancestry, so admixture mapping is well suited to study the genetic basis of this complex disease. We have characterized the admixture proportions in a sample of 286 unrelated T2D patients and 275 controls from Mexico City and we discuss the implications of the results for admixture mapping studies. Admixture proportions were estimated using 69 autosomal ancestry-informative markers (AIMs). Maternal and paternal contributions were estimated from geographically informative mtDNA and Y-specific polymorphisms. The average proportions of Native American, European and, West African admixture were estimated as 65, 30, and 5%, respectively. The contributions of Native American ancestors to maternal and paternal lineages were estimated as 90 and 40%, respectively. In a logistic model with higher educational status as dependent variable, the odds ratio for higher educational status associated with an increase from 0 to 1 in European admixture proportions was 9.4 (95%, credible interval 3.8-22.6). This association of socioeconomic status with individual admixture proportion shows that genetic stratification in this population is paralleled, and possibly maintained, by socioeconomic stratification. The effective number of generations back to unadmixed ancestors was 6.7 (95% CI 5.7-8.0), from which we can estimate that genome-wide admixture mapping will require typing about 1,400 evenly distributed AIMs to localize genes underlying disease risk between populations of European and Native American ancestry. Sample sizes of about 2,000 cases will be required to detect any locus that contributes an ancestry risk ratio of at least 1.5.

Genetic structure and admixture in urban populations of the Argentine North-West

BACKGROUND

From the ethnic point of view, the Argentine North-West (ANW) constitutes one of the most noticeable areas in the country due to the cultural peculiarities that integrate it to the Andean world and the ethno-historical and demographic characteristics of how it became populated.

AIM

The study analysed the genetic structure and diversity of the ANW urban populations, and the contribution of parental populations to its genetic pool.

SUBJECTS AND METHODS

Previously reported data on allele frequencies of HLA-A and HLA-B loci of 1293 individuals from Jujuy, Salta, Tucumán, Santiago del Estero, Catamarca and La Rioja were used. Our estimates include: (a) genetic intra-population diversity; (b) genetic distances between populations; (c) linkage disequilibrium (LD); (d) admixture rates and genetic distances with respect to three parental populations (European, American Indian and African).

RESULTS

Low intra-population genetic differentiation and low genetic distances between populations were found. Differential LD distribution varied according to province, with 60% variance due to intra-population differences. The Spanish contribution (50%) predominated in ANW, followed by the American Indian (40%) and African (10%) contributions, and a marked inter-population heterogeneity of genetic admixture rates was observed. The shortest genetic distance was found in the American Indian parental population, and the longest in the African parental population.

CONCLUSION

Five hundred years after the Spanish conquest, urban populations at ANW that have probably been subject to the same evolutionary forces present low genetic diversity and a similar genetic structure. Genetic distances and admixture percentages observed agree with census and ethno-historical data on settlement in the region.

Admixture analysis of a rural population of the state of Guerrero, Mexico

We studied 156 individuals of Native American descent from the city of Tlapa in the state of Guerrero in western Mexico. Most individuals' ethnicity was either Nahua, Mixtec, or Tlapanec, but self-identified Mestizos and individuals of mixed ethnicities were also included in the sample. We typed 24 autosomal, one Y-chromosome, and four mitochondrial ancestry-informative markers (AIMs) to estimate group and individual admixture proportions, and determine whether the admixture process involved directional gene flow between parental groups. When genetically defined (GD) Mestizos were excluded from the analysis, Native American ancestry represented approximately 98% of the population's gene pool, while European and West African ancestry represented approximately 1% each. Maternally inherited markers also showed an exceptionally high Native American contribution (98.5%), as did the paternally inherited marker, DYS199 (90.7%). We did not detect genetic structure in this population using these AIMs, which appears consistent with the homogeneity of the sample in terms of admixture proportions. The addition of GD Mestizos to the sample did not produce a considerable change in admixture estimates, but it had a major effect on population structure. These results show that the population of Tlapa in Guerrero, Mexico, has experienced little admixture with Europeans and/or West Africans. They also show that the impact of a small number of admixed individuals on an otherwise homogeneous population might have profound implications on subsequent ancestry/phenotype analysis and mapping strategies. We suggest that heterogeneity is a major characteristic of Mexican populations and, as a consequence, should not be disregarded when designing epidemiological studies of Mexican and Mexican American populations.

Genetic admixture of European FRDA genes is the cause of Friedreich ataxia in the Mexican population

Friedreich ataxia accounts for approximately 75% of European recessive ataxia patients. Approximately 98% of pathogenic chromosomes have large expansions of a GAA triplet repeat in the FRDA gene (E alleles), and strong linkage disequilibrium among polymorphisms spanning the FRDA locus indicates a common origin for all European E alleles. In contrast, we found that only 14 of 151 (9.3%) Mexican Mestizo patients with recessive ataxia were homozygous for E alleles. Analysis of polymorphisms spanning the FRDA locus revealed that all Mestizo E alleles had the common European haplotype, indicating that they share a single origin. Genetic admixture levels were determined, which revealed that the relative contributions to the Mestizo FRDA gene pool by Native American and European genes were 76-87% and 13-24%, respectively, commensurate with the observed low prevalence of Friedreich ataxia in Mestizos. This indicates that Friedreich ataxia in Mexican Mestizos is due to genetic admixture of European mutant FRDA genes in the Native American gene pool that existed prior to contact with Europeans.

HLA class II genotypes in Mexican Mestizo patients with myasthenia gravis

Myasthenia gravis is an autoimmune, heterogeneous disorder, characterized by the presence of antibodies against acetylcholine receptors at the neuromuscular junction. There is a strong evidence that an individual's genetic composition is an important predisposing factor for the development of the disease. To correlate HLA class II genotypes with thymic pathology in Mexican Mestizo patients who had been subjected to thymectomy. HLA class II genes were analyzed in 60 patients and in 99 healthy ethnically matched controls. Thymic hyperplasia, atrophy, thymoma, and normal histology were encountered in 56, 33, 8 and 2% of patients, respectively. HLA-DR11 was significantly increased in patients with thymoma compared with healthy controls (pC = 0.001, OR = 13.35, 95% CI 3.5-51.3), compared with the subgroup of hyperplasia patients (pC = 0.005, OR = 15.5, 95% CI 2.78-95.58) and with the atrophy subgroup (pC = 0.04, OR = 10.5, 95% CI 1.75-70.95). This study provides the evidence of an association between HLA class II alleles with clinical and genetic heterogeneity in myasthenia gravis, particularly in those with thymoma (HLA-DR11).

Gene admixture in the Costa Rican population

The general population of Costa Rica has sometimes been considered to be the product of an amalgamation of groups of diverse origin. To determine the magnitude of accumulated admixture since Spanish colonization, 11 classic genetic markers were analyzed in a total of 2196 individuals originating from five distinct regions of the country. A maximum likelihood approach was used. The proportions of genes of European, Amerindian and African ancestry were found to be 61%, 30% and 9% of the total population, respectively. Variation was observed at a regional level, with an increased European influence in the North (66%) and Central (65%) regions. Meanwhile an increase in Amerindian ancestry was found in the South (38%), and a higher incidence in the contribution of African genes was detected in the coastal regions (13% in the Atlantic and 14% in the North Pacific). A principal component (PC) analysis showed that 76% of the existing variability can be explained by the first two PCs, which is in agreement with the variations observed in the admixture process by geographic area. It has been concluded that the Costa Rican population is truly trihybrid, similar to populations in other Latin American countries; however, it differs from them fundamentally by the proportion of gene flow from ancestral populations.

LMP2 and LMP7 gene polymorphism in Mexican populations: Mestizos and Amerindians

Low molecular weight polypeptide (LMP) genes are located within the major histocompatibility complex and have been associated with autoimmune diseases such as ankylosing spondylitis. In order to define the distribution of LMP genes in Mexican populations, the LMP2 and LMP7 polymorphism was analyzed in 312 Mexican individuals (95 Mexican Mestizos, 48 Nahuas, 56 Mazatecans, 50 Teenek, and 63 Mayos) belonging to different ethnic groups. In Mexican populations both Mestizos and Amerindians presented similar distribution of LMP2 and LMP7 polymorphisms, except Nahuas and Mayos who presented the higher frequencies of LMP2-H/H and the lowest frequencies of LMP2-H/R genotypes (P < 0.05 when compared with Mexican Mestizos). The LMP7-K/K genotype was absent in Nahuas, Teenek and Mayos and only one Mazatecan individual presented this genotype. Differences with other populations were found in Mexicans. An increased frequency of LMP2-H and a decreased frequency of LMP2-R alleles were observed in Mexican Amerindians (Nahuas and Mayos) when compared with Brazilian Amerindians (Kaingang and Guarani) and Caucasians (Spaniards) (P < 0.05). All Mexican populations (Mestizos and Amerindians) presented an increased frequency of LMP7-Q allele and a decreased frequency of LMP7-K allele when compared to Brazilian Amerindians (Kaingang), Caucasians (United States) and Asian (Japan) populations (P < 0.05). Genetic distances showed that Mexican Mestizos have an important relation with Spaniards and with all Mexican Amerindians. The present data corroborate the influence of Spaniard and Amerindian genes in the Mexican Mestizo population and could help to define the true significance of LMP polymorphism as genetic and evolutive marker in the Amerindian populations.

Genetic admixture in three Mexican Mestizo populations based on D1S80 and HLA-DQA1 loci

This study compares genetic polymorphisms at the D1S80 and HLA-DQA1 loci in three Mexican Mestizo populations from three large states (Nuevo León, Jalisco, and the Federal District). Allele frequency distributions are relatively homogenous in the three samples; only the Federal District population shows minor differences of the HLA-DQA1 allele frequencies compared with the other two. In terms of genetic composition, these Mestizo populations show evidence of admixture with predominantly Spanish-European (50-60%) and Amerindian (37-49%) contributions; the African contribution (1-3%) is minor. Together with the observation that in Nuevo León, the admixture estimates based on D1S80 and HLA-DQA1, are virtually the same as those reported earlier from blood group loci, suggests that DNA markers, such as D1S80 and HLA-DQA1 are useful for examining genetic homogeneity/heterogeneity across Mestizo populations of Mexico. The inverse relationship of the proportion of gene diversity due to population differences (Gst) to within population gene diversity (Hs) is also consistent with theoretical predictions, supporting the use of these markers for population genetics studies.

Tumor necrosis factor-alpha promoter polymorphisms in Mexican patients with systemic lupus erythematosus (SLE)

The major histocompatibility (MHC) genes including TNF-alpha, HSP70 and HLA genes have been associated with systemic lupus erythematosus (SLE) in several populations. In this study we analyze the polymorphism of TNF-alpha promoter in 51 Mexican Mestizo SLE patients and 55 ethnically-matched healthy controls by polymerase chain reaction methods. No statistically significant differences were observed in the TNF -308 allele and genotype distribution between patients and healthy controls. However, we found a significant increase in the TNF G/A -238 genotype and in the TNFA -238 allele frequencies in the SLE group when compared with healthy controls (Pc = 0.03, OR = 4.77 and Pc = 0.02, OR = 3.62, respectively). DRB1 analysis showed a similar distribution in patients and controls. Linkage disequilibrium was observed for five haplotypes: DRB1*1401-TNFA-238 (D = 0.84; D' = 1.0; P = 0.015); DRB1*0301-TNFA-238 (D = 1.38; D' = 0.41; P = 0.042); DRB1*1106-TNF2-308 (D = 0.9; D' = 1.0; P = 0.0006); DRB1*1104-TNF2-308 (D = 0.83; D' = 0.45; P = 0.02) and DRB1*1406-TNF2-308 (D = 0.83; D' = 0.45; P = 0.02). Our data suggest that the association between the TNF-alpha -238 polymorphism and SLE could play a major role in disease susceptibility.

Class II allele and haplotype frequencies in Mexican systemic lupus erythematosus patients: the relevance of considering homologous chromosomes in determining susceptibility

The aim of the present study was to determine the relevant major histocompatibility complex (MHC) class II alleles in the genetic susceptibility to systemic lupus erythematosus (SLE) in Mexican Mestizo patients. We examined the gene and haplotype frequencies of the HLA-DRB1, DQA1 and DQB1 alleles by polymerase chain reaction-sequence-specific oligonucleotide probes in 81 Mexican SLE Mestizo patients and 99 ethnically matched controls. We found a significantly increased frequency of the HLA-DRB1*0301 (p(c) = 0.031, odds ratio = 2.63) allele and significantly decreased frequencies of the DRB1*0802 (p(c) = 0.035) and DRB1*1101 (p(c) = 0.037) alleles in the SLE group. Haplotype analysis showed increased frequencies of DRB1*0301-DQA1*0501-DQB1*0201 (p(c) = 0.017, odds ratio = 2.97), and decreased frequency of DRB1*0802-DQA1*0401-DQB1*0402 (p(c) = 0.034) in SLE patients. The most frequently detected haplotypes in SLE patients showed different haplotypic combinations in the homologous chromosome from those found in controls. Thus, the combinations detected in SLE patients were either not detected in the control group or infrequently found. The results suggest that the DRB1*0301 is the principal class II allele associated with the genetic susceptibility to SLE in Mexican patients and that the presence of a specific haplotype of the homologous chromosome in patients with DRB1*0407-DQA1*03-DQB1*0302 and DRB1*1501-DQA1*0102-DQB1*0602 haplotypes could have an additive effect on the susceptibility to the disease. Finally, the low frequency of the DRB1*0301 and DRB1*1501 alleles in the control population suggests that the genetic admixture between Mexican Indians and Caucasian populations was an event that could have increased the risk of Mexicans to develop SLE.

mtDNA affinities of the peoples of North-Central Mexico

mtDNA haplotypes of representatives of the cosmopolitan peoples of north-central Mexico were studied. Two hundred twenty-three samples from individuals residing in vicinities of two localities in north-central Mexico were analyzed. A combination of strategies was employed to identify the origin of each haplotype, including length variation analysis of the COII and tRNALYS intergenic region, nucleotide sequence analysis of control region hypervariable segment 1, and RFLP analysis of PCR products spanning diagnostic sites. Analysis of these data revealed that the majority of the mtDNA haplotypes were of Native American origin, belonging to one of four primary Native American haplogroups. Others were of European or African origin, and the frequency of African haplotypes was equivalent to that of haplotypes of European derivation. These results provide diagnostic, discrete character, molecular genetic evidence that, together with results of previous studies of classical genetic systems, is informative with regard to both the magnitude of African admixture and the relative maternal contribution of African, European, and Native American peoples to the genetic heritage of Mexico. Phylogenetic analysis revealed that African sequences formed a basal, paraphyletic group.

HLA-DRB and HLA-DQB loci in the genetic susceptibility to develop glaucoma in Mexicans

PURPOSE

Glaucoma is a clinically heterogeneous disease with a pathophysiology that may include genetic susceptibility, possibly associated with an immunologic disorder. The aim of this study was to determine whether the DNA polymorphisms located in the HLA-DRB1 and HLA-DQB1 genes show a specific association pattern in Mexican mestizo patients with primary open-angle glaucoma.

METHODS

This was a cross-sectional, case-control, multicenter study. We analyzed the HLA-DRB1 and DQB1 loci of 81 Mexican mestizo nonrelated patients with primary open-angle glaucoma and 98 healthy ethnic matched control subjects. Patients were diagnosed clinically and by visual fields examination. HLA typing was performed by PCR-SSO reverse dot blot.

RESULTS

We documented increased frequencies of HLA-DRB1*0301, DRB1*1101, DRB1*0701, DRB1*1402, DQB1*0302, and DQB1*0301; however, none of them were significantly different from normal control subjects. Haplotype analysis showed that the HLA-DRB1*0407-DQB1*0302 haplotype is significantly increased in patients compared with control subjects (P = .0001).

CONCLUSIONS

The haplotype HLA-DRB1*0407-DQB1*0302 is common among Mexican mestizo (haplotype frequency = 0.102), and it was increased in our patients (haplotype frequency = 0.259, P = .0001). This may reflect an independent association of this haplotype with the disease as the result of linkage disequilibrium or the influence of a neighboring gene. The pathophysiology of this illness is uncertain, and further studies are needed regarding the genetic susceptibility to develop primary open-angle glaucoma.

HLA-DRB1 alleles associated with susceptibility or resistance to rheumatoid arthritis, articular deformities, and disability in Mexican Americans

OBJECTIVE

To study the genetics (HLA-DRB1 allele associations) of rheumatoid arthritis (RA) susceptibility and severity among Mexican Americans, an important, but understudied, US population.

METHODS

HLA-DRB1 alleles were compared between 141 Mexican American patients with RA and 54 unrelated Mexican Americans without RA, and the association of these alleles with articular deformities and disability was examined. HLA-DRB1 alleles were typed using polymerase chain reaction-sequence-specific primer amplification and were classified according to the 1996 World Health Organization nomenclature.

RESULTS

Of the 141 patients, 105 (74%) had at least 1 copy of the shared epitope (SE) sequence, compared with 29 (54%) of the 54 controls (P = 0.007). A significant gene-dose effect was observed, with 31 patients (22%) being homozygous for the SE compared with 1 (2%) of the controls (P = 0.004). In terms of disease severity, only 3% of RA patients who were "null" for the SE were outliers in the rate of development of articular deformities, compared with 10% of heterozygotes and 27% of homozygotes (P = 0.002). Patients who were DRB1*08 positive had significantly fewer deformities per year of disease and a slower rate of development of disability than did patients with other DRB1 alleles.

CONCLUSION

HLA-DRB1 alleles containing the SE are associated with susceptibility to RA in Mexican Americans, and may also be associated with a more rapid development of articular deformities and disability. HLA-DRB1*08 appears to have a protective influence on RA susceptibility and disease severity in Mexican Americans.

Genetic features of Mexican women predisposing to cancer of the uterine cervix

Cervical carcinoma is the most common neoplasia in Mexican women. Previous studies report association of this neoplasia with the major histocompatibility complex (MHC) antigens in Caucasians. In the present study, we compared antigen frequencies of class I and class II MHC phenotypes in patients and ethnically matched healthy controls. Patients had significantly increased frequencies of HLA-A2 (PC = .000003) and HLA-DR5 (PC = .01) as compared with healthy controls. Conversely, we found a significant decrease of HLA-DR6 (PC = .01), HLA-DR2 (PC = .0005) and HLA-DR1 (PC = .0009) as compared with healthy controls. These results confirm some previous studies on HLA-associations with cervical carcinoma and reinforce the theory of independent mechanisms of MHC class I and class II genes in the etiopathogenesis of this disease.

Relationship of anticardiolipin antibodies and antiphospholipid syndrome to HLA-DR7 in Mexican patients with systemic lupus erythematosus (SLE)

We studied IgG and IgM anticardiolipin antibodies (aCL) by an ELISA method in 80 Mexican systemic lupus erythematosus (SLE) patients and 378 of their first degree relatives. Sixty five percent of SLE patients and 16% of their relatives were positive for aCL. We also determined allele and haplotype frequencies of Major Histocompatibility Complex (MHC) genes (classes I, II and III) in both patients and relatives. MHC allele and haplotype frequencies of aCL positive and negative individuals were compared to those of normal ethnically matched controls. SLE patients with aCL had statistically significant increased corrected frequencies of HLA-DR3 (pC = 0.04, RR = 2.78); DR7 (pC = 0.005), RR = 3.42) and DQ2 (pC = 0.003, RR = 2.58) antigens. Their first degree relatives positive for aCL also had increased frequency of HLA-DR7 but it did not remain significant after correcting the P value. On the other hand, SLE patients negative for aCL had a moderate increased frequency of DR3 and DQ2 but not of DR7. These results suggest that DR7 associates with the presence of aCL. The distribution of MHC alleles in SLE patients positive for aCL resembles that found in their aCL positive first degree relatives. Since the presence of the antibody is not sufficient to predict a clinical outcome, we studied those patients with reliable clinical data regarding the presence of the antiphospholipid syndrome (aPLS). SLE patients with aPLS had significantly increased frequency of DR7 (pC = 0.004), as did those with probable aPLS (pC = 0.05), while the frequency of DR7 in SLE patients in the doubtful or negative aPLS categories was no different from normal controls. These data support a possible role of DR7 in the development of aCL in SLE patients and their relatives and suggest a contribution of this class II MHC antigen to the development of aPLS within SLE.

Biological and sociocultural approaches of histoplasmosis in the State of Guerrero, Mexico

Histoplasmosis is a deep mycosis with a high prevalence in America. Its aetiological agent, Histoplasma capsulatum, is found in Mexico, mainly in confined spaces, where it grows on bat guano or bird droppings. A research project has been developed in the State of Guerrero, Mexico, where many contaminated caves and mines are visited by individuals and epidemic outbreaks have been recorded. Data concerning human skin test response to histoplasmin antigen, host genetic predisposition to Histoplasma infection, sociocultural, socioeconomical and ethnobiological aspects of the disease in Guerrero are summarized in this paper.

The role of HLA-DR alleles and complotypes through the ethnic barrier in systemic lupus erythematosus in Mexicans

Alleles of the major histocompatibility complex (MHC) have been recognized as genetic factors for the development of SLE. The [HLA-B8; SC01; DR3] extended haplotype seems to be relevant in patients from white European descent, pertinent alleles, however, are difficult to select on haplotypes with linkage disequilibrium. Studies in non-Caucasian patients are therefore mandatory. Admixture estimates in Mexicans have shown a proportion of 56% of Indian genes, 40% of Caucasian genes and from 4 to 12% of Black genes. In order to determine the relevant MHC loci in the genetic susceptibility for SLE we studied Class I, II and III alleles in 102 Mexican SLE patients and 350 of their first degree relatives and compared these two groups to another one composed by 200 ethnically matched normal individuals. We found significantly increased frequencies of HLA-DR3 (pC = 0.03, RR = 2.56) and DR7 (pC = 0.004, RR = 3.08) in SLE patients as compared to controls. On the other hand, first degree relatives had a significantly increased frequency of HLA-DR7 (pC = 0.01, RR = 2.98). There were 21 out of 33 HLA-DR3 haplotypes with complotypes other than SC01 and 25 out 37 SC01 haplotypes with DR alleles other than DR3. Nevertheless, [SC01; DR3] haplotypes were also increased (pC = 0.01, RR = 12.4). After removing [HLA-B8; SC01; DR3] haplotypes, DR3 was the only allele that remained significantly increased (p = 0.04, RR = 2.1). We also found in SLE patients significantly decreased frequencies of the autochthonous Mexican alleles (A30, B39 and DR4) and no deviation from normality of any of the HLA-DQ alleles. These data suggest a fundamental role of the HLA-DR3 allele in the predisposition to SLE in Mexican patients which might be hightened by genes located around the class III MHC region. They also substantiate the pertinence of ethnic admixture estimates in modern human populations.

Racial admixture in a Mestizo population from Mexico City

Seven genetic systems were used to investigate the racial composition of a sample from a low-income Mexico City Mestizo group, finding estimates of 0.590, 0.348, and 0.062 of Indian, White, and Black ancestry, respectively. The results are similar to another Mexico City group studied previously and to several Mestizo populations from different parts of the country. The one thing in common in all these groups is low socioeconomic status. There is only one report suggesting that Mexico City Mestizos have around 70% White ancestry, and there is reason to believe the sample was taken from a high socioeconomic group. It is suggested that low socioeconomic Mexican Mestizo groups are characterized by a high Indian ancestry, above 50%. © 1995 Wiley-Liss, Inc.

HLA-B alleles and complotypes in Mexican patients with seronegative spondyloarthropathies

OBJECTIVES

To analyse major histocompatibility complex (MHC) haplotypes in Mexican mestizo patients with seronegative spondyloarthropathies (SSpA) and normal controls, to discover if there are other antigens, besides B27, in the HLA region that might show association with the disease.

METHODS

The study included 100 Mexican mestizo patients with SSpA and 200 of their first degree relatives. These groups were compared with 85 ethnically matched controls. The class I and class III MHC antigens were obtained by standard methods. The significance of differences between patients and controls was tested by chi 2 analysis; linkage disequilibrium among the different alleles in each haplotype was estimated by computing delta values.

RESULTS

We found a significantly increased frequency of the HLA-B27 antigen (pcorr. = 1 x 10(-5), odds ratio (OR) = 33.4, 95% confidence interval (CI) = 9.3-142.0). In the group of 45 SSpA patients negative for the B27 antigen, independent increased frequencies of HLA-B49 antigen (pcorr. = 0.03, OR = 6.5, 95% CI = 1.5-32.8)) and the FC31 complotype (pcorr. = 0.04, OR = 3.7, 95% CI = 1.2-11.1) were found. Significant delta values were obtained for the [B27;SC30] haplotype (p = 0.0005) but not for haplotypes marked by the FC31 complotype. HLA-B antigens on the homologous chromosome in B27 positive patients were mainly HLA-B51 (18%) and HLA-B60 (16%); however, the observed genotypes B27/B51 and B27/B60 were not significantly different than expected from the allele frequencies alone.

CONCLUSIONS

These data suggest that in Mexicans additional genes within the MHC region besides the HLA-B27 antigen, might be related to the genetic susceptibility for developing SSpA. Relevant antigens included the HLA-B49 and the FC31 complotype.