Synergistic effect of the genetic polymorphisms of the renin-angiotensin-aldosterone system on high-altitude pulmonary edema: a study from Qinghai-Tibet altitude

Association of combined -344T/C and K173R polymorphisms in aldosterone synthase gene with type 2 diabetes mellitus in the Moroccan population

Background: Aldosterone synthase (CYP11B2) is crucial for aldosterone production, and variations in its gene may influence type 2 diabetes mellitus (T2DM) development. This study explores the link between two single nucleotide polymorphisms (SNPs) in the CYP11B2 gene - -344T/C and K173R and T2DM in the Moroccan population . Methods: The research involved 86 individuals with T2DM and 75 control subjects. Genotyping for the -344T/C and K173R SNPs was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis . Result: Results indicated significant differences in the genotype and allelic distribution of the CYP11B2 K173R polymorphism between T2DM patients and control subjects, with P-values of 0.02 and 0.04, respectively. The -344T/C polymorphism showed no significant genomic level differences, but its allelic variations were statistically significant (P=0.01), indicating a notable association between the C allele and T2DM. Furthermore, the K173R polymorphism was found to significantly increase T2DM risk, with a 2.34-fold higher risk in individuals carrying the KR genotype. The study also examined the combined effect of these SNPs. The dominant model analysis (TT vs. TC+CC and KK vs. KR+RR) showed significant differences between T2DM patients and controls for both SNPs. Additionally, a haplotype-based analysis revealed that the C-R haplotype was associated with an increased risk of T2DM. Conclusion: Our study suggests a significant association between the CYP11B2-K173R polymorphism and T2DM in the Moroccan population. Conversely, while the CYP11B2 -344T/C polymorphism exhibits a significant difference in allelic distribution, no significant difference is observed at the genomic level.

Association of variants m.T16172C and m.T16519C in whole mtDNA sequences with high altitude pulmonary edema in Han Chinese lowlanders

Background

High altitude pulmonary edema (HAPE) is a hypoxia-induced non-cardiogenic pulmonary edema that typically occurred in un-acclimatized lowlanders, which inevitably leads to life-threatening consequences. Apart from multiple factors involved, the genetic factors also play an important role in the pathogenesis of HAPE. So far, researchers have put more energy into the nuclear genome and HAPE, and ignored the relationship between the mitochondrion DNA (mtDNA) variants and HAPE susceptibility.

Methods

We recruited a total of 366 individuals including 181 HAPE patients and 185 non-HAPE populations through two times. The first time, 49 HAPE patients and 58 non-HAPE individuals were performed through whole mtDNA sequences to search the mutations and haplogroups. The second time, 132 HAPE patients and 127 non-HAPE subjects were collected to apply verifying these mutations and haplogroups of mtDNA with the routine PCR method.

Results

We analyzed and summarized the clinical characteristics and sequence data for the 49 HAPE patients and 58 non-HAPE individuals. We found that a series of routine blood indexes including systolic arterial blood pressure (SBP), heart rate (HR), white blood cell (WBC), and C-reactive protein (CRP) in the HAPE group presented higher and displayed significant differences compared with those in the non-HAPE group. Although the average numbers of variants in different region and group samples were not statistically significant (P > 0.05), the mutation densities of different regions in the internal group showed significant differences. Then we found two mutations (T16172C and T16519C) associated with the HAPE susceptibility, the T16172C mutation increased the risk of HAPE, and the T16519C mutation decreased the HAPE rating. Furthermore, the two mutations were demonstrated with 132 HAPE patients and 127 non-HAPE individuals. Unfortunately, all the haplogroups were not associated with the HAPE haplogroups.

Conclusions

We provided evidence of differences in mtDNA polymorphism frequencies between HAPE and non-HAPE Han Chinese. Genotypes of mtDNA 16172C and 16519C were correlated with HAPE susceptibility, indicating the role of the mitochondrial genome in the pathogenesis of HAPE.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01791-1.

Comparative transcriptomic and proteomic analyses provide insights into functional genes for hypoxic adaptation in embryos of Tibetan chickens

The Tibetan chicken is a unique breed that has adapted to the high-altitude hypoxic conditions of the Tibetan plateau. A number of positively selected genes have been reported in these chickens; however, the mechanisms of gene expression for hypoxia adaptation are not fully understood. In the present study, eggs from Tibetan and Chahua chickens were incubated under hypoxic and normoxic conditions, and vascularization in the chorioallantoic membrane (CAM) of embryos was observed. We found that the vessel density index in the CAM of Tibetan chickens was lower than in Chahua chickens under hypoxia conditions. Transcriptomic and proteomic analyses of CAM tissues were performed in Tibetan and Chahua chicken embryos under hypoxic incubation using RNA-Seq and iTRAQ. We obtained 160 differentially expressed genes and 387 differentially expressed proteins that were mainly enriched in angiogenesis, vasculature development, blood vessel morphogenesis, blood circulation, renin-angiotensin system, and HIF-1 and VEGF signaling pathways. Twenty-six genes involved in angiogenesis and blood circulation, two genes involved in ion transport, and six genes that regulated energy metabolism were identified as candidate functional genes in regulating hypoxic adaptation of chicken embryos. This research provided insights into the molecular mechanism of hypoxia adaptation in Tibetan chickens.

Interindividual Variation in Cardiorespiratory Fitness: A Candidate Gene Study in Han Chinese People

Cardiorespiratory fitness, as assessed through peak oxygen uptake (VO2peak), is a powerful health indicator. We aimed to evaluate the influence of several candidate causal genetic variants on VO2peak level in untrained Han Chinese people. A total of 1009 participants (566 women; age [mean ± SD] 40 ± 14 years, VO2peak 29.9 ± 7.1 mL/kg/min) performed a maximal incremental cycling test for VO2peak determination. Genomic DNA was extracted from peripheral whole blood, and genotyping analysis was performed on 125 gene variants. Using age, sex, and body mass as covariates, and setting a stringent threshold p-value of 0.0004, only one single nucleotide polymorphism (SNP), located in the gene encoding angiotensin-converting enzyme (rs4295), was associated with VO2peak (β = 0.87; p < 2.9 × 10-4). Stepwise multiple regression analysis identified a panel of three SNPs (rs4295 = 1.1%, angiotensin II receptor type 1 rs275652 = 0.6%, and myostatin rs7570532 = 0.5%) that together accounted for 2.2% (p = 0.0007) of the interindividual variance in VO2peak. Participants carrying six 'favorable' alleles had a higher VO2peak (32.3 ± 8.1 mL/kg/min) than those carrying only one favorable allele (24.6 ± 5.2 mL/kg/min, p < 0.0001). In summary, VO2peak at the pre-trained state is partly influenced by several polymorphic variations in candidate genes, but they represent a minor portion of the variance.

Angiotensin II receptor 1 gene variants are associated with high-altitude pulmonary edema risk

Previous studies demonstrated that Angiotensin II Receptor 1 (AGTR1) may play an important role in the development of high-altitude pulmonary edema. We envisaged a role for AGTR1 gene variants in the pathogenesis of HAPE and investigated their potential associations with HAPE in a Han Chinese population. We genotyped seven AGTR1 polymorphisms in 267 patients with diagnosed HAPE and 304 controls and evaluated their association with risk of HAPE. Statistically significant associations were found for the single nucleotide polymorphisms (SNPs) rs275651 (p = 0.017; odds ratio [OR] = 0.65) and rs275652 (p = 0.016; OR = 0.64). Another SNP rs10941679 showed a marginally significant association after adjusting for age and sex in the additive genetic model (adjusted OR = 1.44, 95% CI = 1.01-2.04, p = 0.040). Haplotype analysis confirmed that the haplotype "AG" was associated with a 35% reduction in the risk of developing HAPE, while the haplotype "AA" increased the risk of developing HAPE by 44%. These results provide the first evidence linking genetic variations in AGTR1 with HAPE risk in Han Chinese individuals.

Association of nineteen polymorphisms from seven DNA repair genes and the risk for bladder cancer in Gansu province of China

Background

Balance of DNA damage and proper repair plays an important role in progression of bladder cancer. Here we aimed to assess the associations of nineteen polymorphisms from seven DNA repair–associated genes (PRAP1, OGG1, APEX1, MUTYH, XRCC1, XRCC2 and XRCC3) with bladder cancer and their interactions in the disease in a Han Chinese population.

Methodology/Principal Findings

A chip-based TaqMan genotyping for the candidate genes was performed on 227 bladder cancer patients and 260 healthy controls. APEX1 rs3136817, MUTYH rs3219493, three SNPs (rs3213356, rs25487 and rs1799782) in XRCC1, and three SNPs (rs1799794, rs861531 and rs861530) in XRCC3 showed significant associations with the risk of bladder cancer. In haplotype analysis, elevated risks of bladder cancer were observed in those with either haplotype GT (OR = 1.56, P = 0.003) of APEX1, or GGGTC (OR = 2.05, P = 0.002) of XRCC1, whereas decreased risks were in individuals with either GCGCC (OR = 0.40, P = 0.001), or GCGTT (OR = 0.60, = 0.005) of XRCC1, or CCC (OR = 0.65, P = 0.004) of MUTYH, or TTTAT (OR = 0.36, P = 0.009) of XRCC3. Interaction analysis showed that the two-loci model (rs1799794 and rs861530) was the best with the maximal testing accuracy of 0.701, and the maximal 100% cross-validation consistency (P = 0.001).

Conclusions

Polymorphisms and haplotypes of DNA repair genes are associated with the risk of bladder cancer, and of which the SNPs (rs1799794 and rs861530) in XRCC3 gene might be two major loci in relation to the susceptibility to bladder cancer in a northwest Chinese population.

SNPs, linkage disequilibrium, and chronic mountain sickness in Tibetan Chinese

Chronic mountain sickness (CMS) is estimated at 1.2% in Tibetans living at the Qinghai-Tibetan Plateau. Eighteen single-nucleotide polymorphisms (SNPs) from nine nuclear genes that have an association with CMS in Tibetans have been analyzed by using pairwise linkage disequilibrium (LD). The SNPs included are the angiotensin-converting enzyme (rs4340), the angiotensinogen (rs699), and the angiotensin II type 1 receptor (AGTR1) (rs5186) from the renin-angiotensin system. A low-density lipoprotein apolipoprotein B (rs693) SNP was also included. From the hypoxia-inducible factor oxygen signaling pathway, the endothetal Per-Arnt-Sim domain protein 1 (EPAS1) and the egl nine homolog 1 (ENGL1) (rs480902) SNPs were included in the study. SNPs from the vascular endothelial growth factor (VEGF) signaling pathway included are the v-akt murine thymoma viral oncogene homolog 3 (rs4590656 and rs2291409), the endothelial cell nitric oxide synthase 3 (rs1007311 and rs1799983), and the (VEGFA) (rs699947, rs34357231, rs79469752, rs13207351, rs28357093, rs1570360, rs2010963, and rs3025039). An increase in LD occurred in 40 pairwise comparisons, whereas a decrease in LD was found in 55 pairwise comparisons between the controls and CMS patients. These changes were found to occur within and between signaling pathways, which suggests that there is an interaction between SNP alleles from different areas of the genome that affect CMS.

Evidence for and Against Genetic Predispositions to Acute and Chronic Altitude Illnesses

MacInnis, Martin J., and Michael S. Koehle. Evidence for and against genetic predispositions to acute and chronic altitude illnesses. High Alt Med Biol. 17:281-293, 2016.-Humans exhibit marked variation in their responses to hypoxia, with susceptibility to acute and chronic altitude illnesses being a prominent and medically important example. Many have hypothesized that genetic differences are the cause of these variable responses to hypoxia; however, until recently, these hypotheses were based primarily on small (and sometimes anecdotal) reports pertaining to apparent differences in altitude illness susceptibility between populations, the notion that a history of altitude illness is indicative of subsequent risk, the heritability of hypoxia-related traits, and candidate gene association studies. In the past 5 years, the use of genomic techniques has helped bolster the claim that susceptibility to some altitude illnesses is likely the result of genetic variation. For each of the major altitude illnesses, we summarize and evaluate the evidence stemming from three important characteristics of a genetic trait: (1) individual susceptibility and repeatability across assessments, (2) biogeographical differences and familial aggregation, and (3) association(s) with genetic variants. Evidence to support a genetic basis for susceptibilities to acute mountain sickness (AMS) and high-altitude cerebral edema (HACE) is limited, owing partially to the subjective and unclear phenotype of AMS and the rarity and severity of HACE. In contrast, recent genomic studies have identified genes that influence susceptibility to high-altitude pulmonary edema, chronic mountain sickness, and high-altitude pulmonary hypertension. The collection of more individual, familial, and biogeographical susceptibility data should improve our understanding of the extent to which genetic variation contributes to altitude illness susceptibility, and genomic and molecular investigations have the potential to elucidate the mechanisms that underpin altitude illness susceptibility.

Biomarkers of hypoxia, endothelial and circulatory dysfunction among climbers in Nepal with AMS and HAPE: a prospective case-control study

BACKGROUND

The mechanisms underlying acute mountain sickness (AMS) and high-altitude pulmonary edema (HAPE) are not fully understood. We hypothesized that regulators of endothelial function, circulatory homeostasis, hypoxia and cell stress contribute to the pathobiology of AMS and HAPE.

METHODS

We conducted a prospective case-control study of climbers developing altitude illness who were evacuated to the CIWEC clinic in Kathmandu, compared to healthy acclimatized climbers. ELISA was used to measure plasma biomarkers of the above pathways.

RESULTS

Of the 175 participants, there were 71 cases of HAPE, 54 cases of AMS and 50 acclimatized controls (ACs). Markers of endothelial function were associated with HAPE: circulating levels of endothelin-1 (ET-1) were significantly elevated and levels of sKDR (soluble kinase domain receptor) were significantly decreased in cases of HAPE compared to AC or AMS. ET-1 levels were associated with disease severity as indicated by oxygen saturation. Angiopoietin-like 4 (Angptl4) and resistin, a marker of cell stress, were associated with AMS and HAPE irrespective of severity. Corin and angiotensin converting enzyme, regulators of volume homeostasis, were significantly decreased in HAPE compared to AC.

CONCLUSION

Our findings indicate that regulators of endothelial function, vascular tone and cell stress are altered in altitude illness and may mechanistically contribute to the pathobiology of HAPE.

Do genetic defects of DNA repair relevant proteins alter susceptibility to hypertension? A case-control study in northeastern Han Chinese

The aim of this study was to examine the individual and interactive associations of five non-synonymous variants of four DNA repair relevant genes (XRCC1, XRCC3, hOGG1, NQO1) with hypertension in a large northeastern Han Chinese population. This was a hospital-based study involving 1009 hypertensive patients and 756 normotensive controls. All five variants satisfied the Hardy-Weinberg equilibrium. With a Bonferroni corrected alpha of 0.05/5, significance was only attained in the genotype (P=0.007) and allele (P=0.006) distributions of rs25487 in XRCC1 gene between patients and controls, with its mutant allele conferring 29% (95% CI: 1.09-1.53; P=0.003), 31% (95% CI: 1.05-1.62; P=0.015) and 66% (95%CI: 1.10-2.52; P=0.016) increased risks of hypertension under the additive, dominant and recessive models, respectively after adjusting for confounders. The frequency of allele combination C-A-C-G-C (alleles in order of rs1799782, rs25487, rs861539, rs1052133 and rs1800566) was significantly higher in patients than in controls (P=0.003), while that of C-G-C-C-C was significantly lower (P=0.001). Interaction analysis failed to identify any suggestive evidence of synergism across five examined variants. Our findings provide evidence for a contributory role of XRCC1 gene rs25487 variant in the development of hypertension, and this variant possibly acted in a recessive pattern.

Association between genetic polymorphisms of ACE & eNOS and diabetic nephropathy

Diabetic nephropathy (DN) is the leading cause of end-stage renal disease, with multiple genetic and environmental factors involving in its etiology. ACE and eNOS gene were considered to have important roles in the development and progression of DN. In this study, a case-control study was carried out to investigate the effects of 7 SNPs in ACE gene and 2 SNPs in eNOS gene in the development of DN in Northern China.7 SNPs including A240T, A2350G, A5466C, A2215G, T3892C, C1237T and C3409T of ACE gene and 2 SNPs (G894T and T786C) of eNOS gene were genotyped by polymerase chain reaction restriction fragment length polymorphism method. 431 type 2 diabetic patients with nephropathy (cases) were compared to 420 type 2 diabetic patients without nephropathy (controls) in the study. Data were analyzed by SPSS 17.0 and HaploView software. The frequency distribution of A2350G, 4 haplotyps in ACE gene and G894T in eNOS gene were demonstrated to be different between case and control groups significantly. Whereas other SNPs and haplotypes had no differences in two cohorts. The results revealed that variations of ACE and eNOS gene had association with DN, which indicated ACE and eNOS gene may play an important role in pathogenesis of DN in Northern Chinese Han population.

Association of 5 Well-Defined Polymorphisms in the Gene Encoding Transforming Growth Factor-β1 With Coronary Artery Disease Among Chinese Patients With Hypertension

We assessed the association between 5 well-defined polymorphisms of the transforming growth factor-β1 (TGFB1) gene and coronary artery disease (CAD) among patients with hypertension from northeast China. All study participants were classified into patients with CAD (n = 679) and controls (n = 686) according to angiographic results. Genotyping was carried out with the ligase detection reaction method. In single-locus analysis, only genotypes of rs1800469 differed significantly between patients with CAD and controls ( P = .001); patients carrying the mutant allele of rs1800469 exhibited a 73% increased risk of CAD ( P < .001). Haplotype analysis indicated that haplotype A-T-T-C-C (alleles in the order of rs1800468, rs1800469, rs1800470, rs1800471, and rs1800472) was associated with a 1.49-fold increased risk ( P = .003). Interaction analysis identified an overall best 3-locus model including rs1800469, rs1800468, and rs1800471 ( P = .003). Taken together, we identified a synergistic interaction between TGFB1 gene multiple polymorphisms that entailed greater risk of CAD in Chinese patients.

Synergistic association between two alcohol metabolism relevant genes and coronary artery disease among Chinese hypertensive patients

Objective

Coronary artery disease (CAD) is a multifactorial and polygenic disease. The aim of this study was to examine the association between six polymorphisms of four alcohol metabolism relevant genes (ADH1B, ADH1C, ALDH1b1, ALDH2) and the risk of CAD in Han Chinese.

Methods and Results

This was a hospital-based case-control study involving 1365 hypertensive patients. All study subjects were angiographically confirmed. Genotypes were determined with ligase detection reaction method. There was no observable deviation from the Hardy-Weinberg equilibrium for six examined polymorphisms in controls. The genotype and allele distributions of ALDH1b1 rs2073478 and ALDH2 rs671 polymorphisms differed significantly between the two groups (P≤0.005), even after the Bonferroni correction. The most common allele combination was A-C-C-G-C-G (alleles in order of rs1229984, rs1693482, rs2228093, rs2073478, rs886205, rs671) and its frequency was slightly higher in controls than in CAD patients (P = 0.067). After assigning the most common allele combination as a reference, allele combination A-C-C-T-C-A, which simultaneously possessed the risk alleles of rs2073478 and rs671 polymorphisms, was associated with a 1.80-fold greater risk of CAD. Further, a two-locus model including rs2073478 and rs671 that had a maximal testing accuracy of 0.598 and a cross-validation consistency of 10 (P = 0.008) was deemed as the overall best MDR model, which was further validated by classical Logistic regression model.

Conclusion

Our findings provide clear evidence for both individual and interactive associations of ALDH1b1 and ALDH2 genes with the development of CAD in Han Chinese.

Association of CYP11B2 polymorphisms with metabolic syndrome patients

Aldosterone synthase is a key enzyme in aldosterone production. Polymorphisms of the aldosterone synthase gene, CYP11B2, have been suggested to be involved in the pathogenesis of diabetes mellitus (DM), hypertension and cardiovascular diseases. In the light of these findings, we hypothesized that CYP11B2 genetic polymorphisms play a role in metabolic syndrome (MetS). Therefore, we investigated the associations of three CYP11B2 polymorphisms [-344T>C, K173R and intron 2 conversion (IC)] with Korean MetS patients. In total, 640 subjects comprising 320 cases and 320 control individuals) were included in the present study. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) techniques were used to assess CYP11B2 polymorphisms. The CYP11B2 -344T>C, K173R and IC polymorphisms did not exhibit a significant difference in the genotype and allele frequencies between the MetS and control groups. However, the -344T>C polymorphism in males and haplotypes comprising the three polymorphisms were associated with susceptibility to MetS. Thus, the pattern of haplotype associations was gender-specific. Based on these results, the -344T>C polymorphism in males and haplotypes of the CYP11B2 gene potentially affect MetS susceptibility. These findings remain to be confirmed in various ethnic populations with a larger sample size.

Interactive contribution of serine/threonine kinase 39 gene multiple polymorphisms to hypertension among northeastern Han Chinese

Serine/threonine kinase 39 (STK39) gene has been reported to be a hypertension-susceptibility gene by a recent genome-wide association study in Western populations. To validate this finding in Chinese, we focused on five well-characterized common polymorphisms in STK39 gene to examine their potential association with hypertension in a large northeastern Han population. This is a hospital-based case-control study involving 1009 hypertensive patients and 756 normotensive controls. Data were analyzed by the Haplo.Stats and multifactor dimensionality reduction (MDR) softwares. The genotype and allele distributions of rs6749447, rs3754777 and rs6433027 differed significantly between patients and controls (P < 0.001) even after the Bonferroni correction. The majority of derived haplotypes also showed remarkable differences between the two groups (P ≤ 0.001). As indicated by MDR analysis, a three-locus model including rs6749447, rs35929607 and rs3754777 was selected as the overall best with a larger testing accuracy of 0.7309 and a maximum cross-validation consistency of 10 (P < 0.001). The utility of this model was reinforced by a Logistic regression analysis. Taken together, our findings suggest the potential interactive role of STK39 gene multiple polymorphisms in the development of hypertension among northeastern Han Chinese.

Genetic variants of the matrix metalloproteinase family genes and risk for hypertension: a case-control study among northeastern Han Chinese

In this study, we sought to examine the association between 10 genetic variants in the matrix metalloproteinase (MMP) family genes and the risk of hypertension among northeastern Han Chinese. This was a hospital-based case-control study involving 1009 sporadic hypertensive patients and 756 age-, gender- and ethnicity-matched normotensive controls. The genotypes of the 10 examined variants were determined by PCR-ligase detection reaction method. The genotype/allele distributions of rs3025058 and rs679620 differed significantly between patients and controls, with a Bonferroni corrected α of 0.05/10. The probability of having hypertension was significant for rs3025058 under the additive (odds ratio; 95% confidence interval; P: 1.33; 1.16-1.53; <0.001) and dominant (1.43; 1.18-1.73; <0.001) models and was significant for rs679620 under the additive (1.27; 1.1-1.46; <0.001) model after adjusting for confounders. In a combined analysis, when compared with the reference group (score<3.5 for unfavorable genotypes), participants in the medium- and high-risk groups had odds ratios that increased to 1.61 (95% CI: 1.25-2.51; P<0.001) and 1.92 (95% CI: 1.54-2.39; P<0.001) after adjustment, respectively. Interaction analysis showed that a three-locus model including rs3025058, rs679620 and rs243865 was the best, with a maximum testing accuracy of 0.6605 and a cross-validation consistency of 10 (P=0.0022). Taken together, our findings suggest that the true association between individual variants and the risk of hypertension may not be revealed until combined analyses of multiple variants from genes involving a specific physiological or cellular function are performed. Moreover, we propose a three-locus model that can best characterize the genetic interactions of the MMP multiple gene family.

Gene-gene interactions in renin-angiotensin-aldosterone system contributes to end-stage renal disease susceptibility in a Han Chinese population

Objective. In this study, we investigated whether RAAS gene single nucleotide polymorphisms (SNPs) and their interactions were associated with end-stage renal stage (ESRD). Methodology and Results. This was a case-control study for 647 ESRD cases and 644 controls. AGT (M235T (rs699) and T174M (rs4762)), AGTR1 (A1166C (rs5186) and C573T (rs5182)), ACE (I/D (rs1799752) and G2350A (rs4343)), and CYP11B2 C-344T (rs1799998) were genotyped and compared between cases and controls to identify SNPs associated with ESRD susceptibility. Multifactor dimensionality reduction (MDR) was used to identify gene-gene interactions. Several RAAS genes were associated with ESRD: AGT M235T, ACE I/D, ACE G2350A, and CYP11B2 C-344T. By MDR analysis, a three-locus model (ACE ID/ACE G2350A/CYP11B2 C-344T) of gene-gene interaction was the best for predicting ESRD risk, and its maximum testing accuracy was 56.08% and maximum cross-validation consistency was 9/10. ESRD risk was higher with the simultaneous occurrence of ACE I/D DD-ACE G2350A AA. AGT, ACE, and CYP11B2 gene polymorphisms are associated with ESRD. Conclusions. The gene-gene interaction effects of ACE I/D, ACE G2350A, and CYP11B2 C-344T polymorphisms are more important than individual factors for ESRD development among Han Chinese.

The relationship between seven common polymorphisms from five DNA repair genes and the risk for breast cancer in northern Chinese women

BACKGROUND

Converging evidence supports the central role of DNA damage in progression to breast cancer. We therefore in this study aimed to assess the potential interactions of seven common polymorphisms from five DNA repair genes (XRCC1, XRCC2, XRCC3, XPA and APEX1) in association with breast cancer among Han Chinese women.

METHODOLOGY/PRINCIPAL FINDINGS

This was a case-control study involving 606 patients diagnosed with sporadic breast cancer and 633 age- and ethnicity-matched cancer-free controls. The polymerase chain reaction-ligase detection reaction method was used to determine genotypes. All seven polymorphisms were in accordance with Hardy-Weinberg equilibrium in controls. Differences in the genotypes and alleles of XRCC1 gene rs25487 and XPA gene rs1800975 were statistically significant between patients and controls, even after the Bonferroni correction (P<0.05/7). Accordingly, the risk for breast cancer was remarkably increased for rs25487 (OR = 1.28; 95% CI: 1.07-1.51; P = 0.006), but decreased for rs1800975 (OR = 0.77; 95% CI: 0.67-0.90; P = 0.001) under an additive model at a Bonferroni corrected alpha of 0.05/7. Allele combination analysis showed higher frequencies of the most common combination C-G-G-C-G-G-G (alleles in order of rs1799782, rs25487, rs3218536, rs861539, rs1800975, rs1760944 and rs1130409) in controls than in patients (PSim = 0.002). In further interaction analysis, two-locus model including rs1800975 and rs25487 was deemed as the overall best model with the maximal testing accuracy of 0.654 and the cross-validation consistency of 10 out of 10 (P = 0.001).

CONCLUSION

Our findings provide clear evidence that XRCC1 gene rs25487 and XPA gene rs1800975 might exert both independent and interactive effects on the development of breast cancer among northern Chinese women.

The contributory role of angiotensin receptor-like 1 gene multiple polymorphisms in hypertension among northeastern Han Chinese

Background and Objective

Via direct sequencing, we have recently identified six common polymorphisms in angiotensin receptor-like 1 (AGTRL1) gene, and found only two polymorphisms were significantly associated with hypertension in a family-based analysis on 1,015 southern Han Chinese. Extending our previous work and considering the ubiquity of epistasis in determining disease susceptibility, we, in this study, sought to explore the potential interaction of AGTRL1 gene six polymorphisms with hypertension in a large northeastern Han Chinese population.

Methods and Results

This was a case-control study involving 1,009 sporadic hypertensive patients and 756 normotensive controls. Data were analyzed by Haplo.Stats and multifactor dimensionality reduction (MDR) softwares. There were no deviations from Hardy-Weinberg equilibrium for all polymorphisms. The genotypes and alleles of rs7119675 and rs11544374 differed significantly between the two groups (P<0.0005), even after the Bonferroni correction. Under three genetic models, significant association was consistently observed for rs7119675 and rs11544374, and this association was independent of confounding factors. Taking rs7119375 as an example, the odds of having hypertension was 2.46 (95% confidence interval (95% CI): 2.06–2.94), 2.82 (95% CI: 2.29–3.46) and 3.97 (95% CI: 2.37–6.64) under additive, dominant and recessive models (P<0.001), respectively, whereas the adjusted risk estimates were slightly attenuated but still significant. The frequencies of most derived haplotypes differed significantly between patients and controls. Haplotype-phenotype analyses indicated marginal association for triglyceride (P_Sim = 0.011) and total cholesterol (P_Sim = 0.025) in patients and for triglyceride in controls (P_Sim = 0.023). The overall best MDR model included rs11544374, rs7119375 and rs948847 with the maximal testing accuracy of 0.737 and cross-validation consistency of 10 out of 10 (P<0.0001). Further interaction entropy graph suggested that the interaction of rs7119375 with rs11544374 and rs948847 was strongly antagonized.

Conclusions

Our findings demonstrate that AGTRL1 genetic polymorphisms might contribute to the development of hypertension independently and/or through complex interaction.

Polymorphisms of angiotensin converting enzyme and nitric oxide synthase 3 genes as risk factors of high-altitude pulmonary edema: a case-control study and meta-analysis

High-altitude pulmonary edema (HAPE) is a non-cardiogenic type of pulmonary edema developing altitudes > 2,500 m. Angiotensin converting enzyme (ACE) and nitric oxide synthase 3 (NOS3) play important roles in regulating pulmonary vascular tone. To assess associations between genetic variants in the ACE and NOS3 genes and HAPE risk, 27 HAPE patients and 108 matched controls were genotyped and analyzed. The indicated HAPE association of the NOS3 G894T (Glu298Asp) single nucleotide polymorphism (SNP), which may change NO production, was further evaluated by a meta-analysis of six studies involving 399 HAPE patients and 495 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were determined with fixed-effects models. Stratification analyses of ethnicity and geographic location were performed. Significant associations were observed for the dominant model in two ACE tag SNPs influencing serum ACE concentrations (rs8066114 polymorphism: GG+CG vs. CC; rs4461142 polymorphism: TT+CT vs. CC). Furthermore, Single-locus analysis indicated significantly different distributions of G allele frequency between the cases (29.63%) and controls (17.13%) for the ACE rs8066114 polymorphism. The case-control distributions of genotype frequencies and T allele frequency of NOS3 G894T (Glu298Asp) polymorphism were significantly higher in the cases than controls, and the NOS3 G894T (Glu298Asp) SNP showed elevated HAPE risk under the dominant model (TT+GT vs. GG). Meta-analysis showed overall association of NOS3 G894T SNP with HAPE risk under the allele contrast and dominant genetic models, which remained significant for Asians. In conclusion, ACE rs8066114 and rs4461142 and NOS3 rs1799983 (G894T) polymorphisms may be associated with increased HAPE risk in Asians.

Association of CYP11B2 polymorphisms with susceptibility to primary aldosteronism: a meta-analysis

The association of CYP11B2 gene polymorphisms with the risk of primary aldosteronism (PA) was controversial in previous studies. Here we selected two commonly studied CYP11B2 alleles: T-344C, A2718G to explore their associations with PA risk by meta-analyses of published case-control studies. Six electronic databases were searched for relevant studies up to November 2012. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using random or fixed effects model. Seven studies (621 cases and 1027 controls) on T-344C polymorphism, three studies (327 cases and 336 controls) on A2718G polymorphism were finally included. Then significant association was observed between T-344C polymorphism and idiopathic hyperaldosteronism (IHA) under three genetic models (CC vs. TT, OR=0.544, 95% CI=0.324~0.914; CT vs. TT, OR=0.554, 95% CI=0.406~0.757; CC+CT vs. TT, OR=0.542, 95% CI=0.402~0.731). But patients with aldosterone-producing adenoma had no significant association with T-344C polymorphism under all genetic models except CT vs. TT model. Concerning A2718G polymorphism, a decreased PA risk was observed only under GG+GA vs AA model. But this association disappeared after removing the studies not in Hardy-Weinberg equilibrium. The evidence accumulated suggested that -344C allele may be associated with decreased risk of IHA and there was still no enough evidence to indicate the association of A2718G polymorphism with PA risk.

Metabolomic analysis of the plasma of patients with high-altitude pulmonary edema (HAPE) using 1H NMR

Upon rapid ascent to a high altitude, non-acclimatized individuals, although healthy, are highly prone to contracting high-altitude pulmonary edema (HAPE). Early diagnosis is difficult and there is no reliable biomarker available. We used proton ((1)H) NMR metabolomics to profile the altered metabolic patterns of blood plasma from HAPE patients. The plasmas of ten patients with HAPE and ten individuals without HAPE were collected and compared using (1)H NMR spectroscopy. Data were evaluated with several multivariate statistical analyses, including the principal components, the orthogonal partial least-squares discriminant, and the orthogonal signal correction partial least-squares discriminant. Multivariate statistical analyses revealed a significant disparity between subjects with HAPE and those in the control group. Compared to the plasma of the controls, the HAPE patients had significant increases in valine, lysine, leucine, isoleucine, glycerol phosphoryl choline, glycine, glutamine, glutamic acid, creatinine, citrate, and methyl histidine. These were accompanied by decreases in α- and β-glucose, trimethylamine, and the metabolic products of lipids. The data demonstrate that metabolomics may be effective for the diagnosis of HAPE in the future, and can be used for further understanding HAPE pathogenesis.

Association and interaction of -58C>T and ±9 bp polymorphisms of BDKRB2 gene causing susceptibility to essential hypertension

INTRODUCTION

Bradykinin, a vasodilator by nature has been documented to have a protective role against hypertension and cardiovascular complications. Polymorphisms of bradykinin B2 receptor (BDKRB2) gene are reported to be predisposing factors for hypertension. Evaluation of the association between -58C>T and ±9 bp polymorphisms of BDKRB2 with essential hypertension (EHT) was attempted.

METHODS

Two hundred and fourteen primary hypertensives and 249 controls were genotyped for the selected markers by polymerase chain reaction, gel electrophoresis (±9 bp), and SSCP (-58C>T).

RESULTS

While -58C>T polymorphism did not reveal any association with EHT, ±9 bp polymorphism showed a significant association with high risk for heterozygotes (+9/-9) when tested against the pooled frequencies of homozygotes (OR [odds ratio] = 1.63, 95% confidence interval [CI] = 1.12-2.38, P = .02), and this risk was 1.7 folds high in males (OR = 1.74, 95% CI = 1.05-2.86, P = .06) and 1.9 folds high in familial cases (OR = 1.96, 95% CI = 1.09-3.53, P = .04). In contrast, significant protective effect was observed for -9/-9 genotype against EHT when tested under dominant model in general (OR = 0.59, 95% CI = 0.41-0.86, P = .01), in males (OR = 0.49, 95% CI = 0.30-0.82, P = .01), and in familial cases (OR = 0.50, 95% CI = 0.28-0.89, P = .04). Significant risk for +9 bp allele was observed in general (OR = 1.39, 95% CI = 1.05-1.86, P = .04) and in males (OR = 1.65, 95% CI = 1.13-2.41, P = .02). The interaction information analysis revealed a synergistic effect between the two polymorphisms contributing to EHT. +9/+9 genotype of ±9 bp polymorphism when present in combination with CC genotype of -58C>T polymorphism showed 2.2-fold higher risk for developing EHT.

CONCLUSIONS

The results suggest that allele +9 bp might be a risk factor for EHT in general and specially in males. Markers -58C>T and ±9 bp may act synergistically causing susceptibility to EHT.

Hypoxic pulmonary vasoconstriction

It has been known for more than 60 years, and suspected for over 100, that alveolar hypoxia causes pulmonary vasoconstriction by means of mechanisms local to the lung. For the last 20 years, it has been clear that the essential sensor, transduction, and effector mechanisms responsible for hypoxic pulmonary vasoconstriction (HPV) reside in the pulmonary arterial smooth muscle cell. The main focus of this review is the cellular and molecular work performed to clarify these intrinsic mechanisms and to determine how they are facilitated and inhibited by the extrinsic influences of other cells. Because the interaction of intrinsic and extrinsic mechanisms is likely to shape expression of HPV in vivo, we relate results obtained in cells to HPV in more intact preparations, such as intact and isolated lungs and isolated pulmonary vessels. Finally, we evaluate evidence regarding the contribution of HPV to the physiological and pathophysiological processes involved in the transition from fetal to neonatal life, pulmonary gas exchange, high-altitude pulmonary edema, and pulmonary hypertension. Although understanding of HPV has advanced significantly, major areas of ignorance and uncertainty await resolution.

Association of polymorphisms in angiotensin and aldosterone synthase genes of the renin–angiotensin–aldosterone system with high-altitude pulmonary edema

Studies on different populations have suggested variability in individual susceptibility to altitude sickness depending on genetic makeup. The renin–angiotensin–aldosterone system (RAAS) pathway plays a key role in regulation of vascular tone and circulatory homeostasis. The present study was undertaken to investigate the possible association of the RAAS in the development of high-altitude pulmonary edema (HAPE) in lowlanders exposed to high altitude. Three categories of subjects were selected: individuals who developed HAPE on acute induction to high altitude ( HAPE); individuals tolerant to high-altitude exposure who showed no symptoms of HAPE (resistant controls; rCON); and natives of high altitude ( HAN). Genetic variants in the genes of the RAAS such as renin ( REN), angiotensin ( AGT), angiotensin-converting enzyme ( ACE), aldosterone synthase ( CYP11B2) and angiotensin II receptor type 1 ( AGTR1) have been investigated. The T174M polymorphism in AGT showed a significant difference in HAPE and HAN and also HAN and controls. Also, genotyping in the CYP11B2 T-344C promoter region resulted in a significant difference between HAPE and HAN both at genotypic and allelic levels. The genotypic difference was statistically insignificant for the AGTR1 A1166C 3’ UTR. The present investigation demonstrates a possible association between the polymorphisms existing in the RAAS pathway T174M and CYP11B2 C-344T and sensitivity of an individual to develop HAPE. The results also indicate the existence of ethnic variation between the HAN and the other two groups comprising lowlanders.

The ACE gene and human performance: 12 years on

Some 12 years ago, a polymorphism of the angiotensin I-converting enzyme (ACE) gene became the first genetic element shown to impact substantially on human physical performance. The renin-angiotensin system (RAS) exists not just as an endocrine regulator, but also within local tissue and cells, where it serves a variety of functions. Functional genetic polymorphic variants have been identified for most components of RAS, of which the best known and studied is a polymorphism of the ACE gene. The ACE insertion/deletion (I/D) polymorphism has been associated with improvements in performance and exercise duration in a variety of populations. The I allele has been consistently demonstrated to be associated with endurance-orientated events, notably, in triathlons. Meanwhile, the D allele is associated with strength- and power-orientated performance, and has been found in significant excess among elite swimmers. Exceptions to these associations do exist, and are discussed. In theory, associations with ACE genotype may be due to functional variants in nearby loci, and/or related genetic polymorphism such as the angiotensin receptor, growth hormone and bradykinin genes. Studies of growth hormone gene variants have not shown significant associations with performance in studies involving both triathletes and military recruits. The angiotensin type-1 receptor has two functional polymorphisms that have not been shown to be associated with performance, although studies of hypoxic ascent have yielded conflicting results. ACE genotype influences bradykinin levels, and a common gene variant in the bradykinin 2 receptor exists. The high kinin activity haplotye has been associated with increased endurance performance at an Olympic level, and similar results of metabolic efficiency have been demonstrated in triathletes. Whilst the ACE genotype is associated with overall performance ability, at a single organ level, the ACE genotype and related polymorphism have significant associations. In cardiac muscle, ACE genotype has associations with left ventricular mass changes in response to stimulus, in both the health and diseased states. The D allele is associated with an exaggerated response to training, and the I allele with the lowest cardiac growth response. In light of the I-allele association with endurance performance, it seems likely that other regulatory mechanisms exist. Similarly in skeletal muscle, the D allele is associated with greater strength gains in response to training, in both healthy individuals and chronic disease states. As in overall performance, those genetic polymorphisms related to the ACE genotype, such as the bradykinin 2 gene, also influence skeletal muscle strength. Finally, the ACE genotype may influence metabolic efficiency, and elite mountaineers have demonstrated an excess of I alleles and I/I genotype frequency in comparison to controls. Interestingly, this was not seen in amateur climbers. Corroboratory evidence exists among high-altitude settlements in both South America and India, where the I allele exists in greater frequency in those who migrated from the lowlands. Unfortunately, if the ACE genotype does influence metabolic efficiency, associations with peak maximal oxygen consumption have yet to be rigorously demonstrated. The ACE genotype is an important but single factor in the determinant of sporting phenotype. Much of the mechanisms underlying this remain unexplored despite 12 years of research.

Association of angiotensin-converting enzyme gene insertion/deletion polymorphism with high-altitude pulmonary oedema: a meta-analysis

Background and objective: High-altitude pulmonary oedema (HAPE) is a non-cardiogenic hydrostatic oedema involving a genetic component. Considering the low incidence of HAPE, sample sizes in current reports are relatively limited. We aimed to assess the association between the angiotensin-converting enzyme (ACE) I/D polymorphism and HAPE via a meta-analysis of published and unpublished data.

Materials and methods: We searched PubMed, CBM, CNKI, and Cochrane Library Database before 20 November 2010. A random-effects model was applied (STATA) and study quality was assessed in duplicate.

Results: A total of five studies including 305 cases and 662 controls were meta-analysed. The summary odds ratio (OR) indicated that no significant differences in risk of developing HAPE were found between carriers of ACE D and I alleles (OR = 1.20; 95% confidence interval (CI), 0.98–1.48; p = 0.084). Lack of association persisted for genotypes under the recessive mode. However, genotype association under the dominant mode showed D allele carriers significantly conferred a 1.55-fold increased HAPE risk compared with II genotype carriers (95% CI, 1.15–2.08; p = 0.004). Funnel plot and Egger’s test suggested no evidence of publication bias.

Conclusions: Our results supported the notion that ACE D allele carriers were at significant increased risk of developing HAPE.

Evidence for a genetic basis for altitude illness: 2010 update

Altitude illness refers to a group of environmentally mediated pathophysiologies. Many people will suffer acute mountain sickness shortly after rapidly ascending to a moderately hypoxic environment, and an unfortunate few will develop potentially fatal conditions such as high altitude pulmonary edema or high altitude cerebral edema. Some individuals seem to be predisposed to developing altitude illness, suggesting an innate contribution to susceptibility. The implication that there are altitude-sensitive and altitude-tolerant individuals has stimulated much research into the contribution of a genetic background to the efficacy of altitude acclimatization. Although the effect of altitude attained and rate of ascent on the etiology of altitude illness is well known, there are only tantalizing, but rapidly accumulating, clues to the genes that may be involved. In 2006, we reviewed what was then known about the genetics of altitude illness. This article updates that review and attempts to tabulate all the available genetic data pertaining to these conditions. To date, 58 genes have been investigated for a role in altitude illness. Of these, 17 have shown some association with the susceptibility to, or the severity of, these conditions, although in many cases the effect size is small or variable. Caution is recommended when evaluating the genes for which no association was detected, because a number of the investigations reviewed in this article were insufficiently powered to detect small effects. No study has demonstrated a clear-cut altitude illness gene, but the accumulating data are consistent with a polygenic condition with a strong environmental component. The genes that have shown an association affect a variety of biological pathways, suggesting that either multiple systems are involved in altitude pathophysiology or that gene-gene interactions play a role. Although numerous studies have been performed to investigate specific genes, few have looked for evidence of heritability or familial transmission, or for epidemiological patterns that would be consistent with genetically influenced conditions. Future trends, such as genome-wide association studies and epigenetic analysis, should lead to enhanced understanding of the complex interactions within the genome and between the genome and hypoxic environments that contribute to an individual's capacity to acclimatize rapidly and effectively to altitude.

Endothelial nitric oxide synthase gene polymorphisms associated with susceptibility to high altitude pulmonary edema in Chinese railway construction workers at Qinghai-Tibet over 4 500 meters above sea level

OBJECTIVE

To examine whether the polymorphisms of endothelial nitric oxide synthase (eNOS) gene are associated with the susceptibility to high altitude pulmonary edema (HAPE) in Chinese railway construction workers at Qinghai-Tibet where the altitude is over 4 500 m above sea level.

METHODS

A case-control study was conducted including 149 HAPE patients in the construction workers and 160 healthy controls randomly recruited from their co-workers, matching the patients in ethnicity, age, sex, lifestyle, and working conditions. Three polymorphisms of eNOS gene, T-786C in promoter, 894G/T in exon 7, and 27bp variable number tandem repeat (VNTR) in intron 4, were genotyped using polymerase chain reaction (PCR) and confirmed with DNA sequencing.

RESULTS

The frequencies of 894T allele and heterozygous G/T of the 894G/T variant were significantly higher in HAPE patients group than in the control group (P=0.0028 and P=0.0047, respectively). However, the frequencies of the T-786C in promoter and the 27bp VNTR in intron 4 were not significantly different between the two groups. Haplotypic analysis revealed that the frequencies of two haplotypes (H3,T-T-b, b indicates 5 repeats of 27 bp VNTR; H6, C-G-a, a indicates 4 repeats of 27 bp VNTR) were significantly higher in HAPE patients (both Pü0.0001). On the contrary, the frequencies of H1 (T-G-b) and H2 (T-G-a) were lower in HAPE patients than in healthy controls (both Pü0.001).

CONCLUSIONS

Two haplotypes (T-T-b and C-G-a) may be strongly associated with susceptibility to HAPE. Compared with the individual alleles of eNOS gene, the interaction of multiple genetic markers within a haplotype may be a major determinant for the susceptibility to HAPE.

Polymorphisms of renin-angiotensin system genes as a risk factor for high-altitude pulmonary oedema

The genes of the renin—angiotensin system (RAS) play an important role in the regulation of pulmonary vascular tone. Although studies on individual genes polymorphisms have reported association with high-altitude pulmonary oedema (HAPE), studies on multiple genes or epistasis are lacking. We therefore investigated the association of the RAS polymorphisms with HAPE. In a case-control design, we screened 163 HAPE-resistant/controls (HAPE-r) and 160 HAPEpatients (HAPE-p) of Indian origin for eight polymorphisms of four RAS genes, ACE, AGT, AGTR1 and AGTR2. Significant difference in genotype and allele frequencies of the ACE I/D and AGT M235T polymorphisms was observed between HAPE-p and HAPE-r ( p < 0.05). In three-locus haplotype analysis of AGT the haplotype GTM was significantly higher in HAPE-p (29%) and haplotype GTT in HAPE-r (27%) after Bonferroni correction ( p < 0.006). The differences were insignificant for polymorphisms from AGTR1 and AGTR2. The MDR (multifactor dimensional reduction) approach for gene—gene interaction depicted individual polymorphism M235T as the best disease predicting model (cross validation consistency, CVC = 10/10). We found a significant association of D allele of ACE and M allele of AGT with HAPE. The findings are supported at the haplotypic level as well as through nested genetic interaction between the RAS gene polymorphisms using the MDR approach.

Gene-gene interaction filtering with ensemble of filters

Background

Complex diseases are commonly caused by multiple genes and their interactions with each other. Genome-wide association (GWA) studies provide us the opportunity to capture those disease associated genes and gene-gene interactions through panels of SNP markers. However, a proper filtering procedure is critical to reduce the search space prior to the computationally intensive gene-gene interaction identification step. In this study, we show that two commonly used SNP-SNP interaction filtering algorithms, ReliefF and tuned ReliefF (TuRF), are sensitive to the order of the samples in the dataset, giving rise to unstable and suboptimal results. However, we observe that the ‘unstable’ results from multiple runs of these algorithms can provide valuable information about the dataset. We therefore hypothesize that aggregating results from multiple runs of the algorithm may improve the filtering performance.

Results

We propose a simple and effective ensemble approach in which the results from multiple runs of an unstable filter are aggregated based on the general theory of ensemble learning. The ensemble versions of the ReliefF and TuRF algorithms, referred to as ReliefF-E and TuRF-E, are robust to sample order dependency and enable a more informative investigation of data characteristics. Using simulated and real datasets, we demonstrate that both the ensemble of ReliefF and the ensemble of TuRF can generate a much more stable SNP ranking than the original algorithms. Furthermore, the ensemble of TuRF achieved the highest success rate in comparison to many state-of-the-art algorithms as well as traditional χ²-test and odds ratio methods in terms of retaining gene-gene interactions.

Association of the human CYP11B2 gene and essential hypertension in southwest Han Chinese population: a haplotype-based case-control study

Aldosterone synthase produces aldosterone, which regulates electrolytes and thereby blood pressure (BP). The aldosterone-synthase gene (CYP11B2) has been regarded as a candidate gene for essential hypertension. To address this issue, we carried out a haplotype-based, case-control study to explore the association between a human CYP11B2 gene and essential hypertension (EH) in the southwest Han population of China (n = 1020 individuals). Four tag single-nucleotide polymorphisms (SNPs) (rs4536, rs4545, rs3097, and rs3802230) and the C-344T polymorphism, as well as the K173R polymorphism in the CYP11B2 gene, were genotyped using the PCR-RFLP method. Single-locus analysis showed that the C allele of rs3802230 was significantly more prevalent in the EH subjects as compared to control subjects, adjusted for covariates. Haplotype analysis showed that the haplotype AAGC constructed by the tag SNPs (rs4536, rs4545, rs3097, and rs3802230), which carried the susceptible rs3802230 C allele, significantly increased the risk of essential hypertension with an odds ratios equal to 3.56 (P = 0.0001). The present results indicated that the rs3802230 C allele might be a risk marker for essential hypertension and haplotype AAGC might confer high genetic susceptibility to essential hypertension in a southwest Han Chinese population.

Haplotype-based case-control study of the human CYP11B2 gene and essential hypertension in Yi and Hani minorities of China

This haplotype-based case-control study investigated whether the aldosterone synthase gene (CYP11B2) might be implicated in the pathogenesis of essential hypertension in Yi (226 individuals) and Hani (296 individuals) minorities of China. Four tag SNPs (rs4536, rs4545, rs3097, and rs3802230) and the K173R polymorphism were genotyped using the PCR-RFLP method. In the Hani minority, rs4536 was significantly associated with hypertension, after Bonferroni correction. H9 AGGC constructed by tag SNPs was significantly higher in hypertensives than in controls (P = 0.001). Further, we observed that haplotype AGGC remained significantly associated with male hypertension after adjustment for covariates (OR = 3.76, P = 0.002). In the Yi minority, it was found that the CYP11B2 gene was not significantly associated with hypertension. These results indicated that haplotype AGGC conferred an increased risk for hypertension in the Hani minority male. In addition, CYP11B2 may not be associated with hypertension in the Yi minority of China.

The Generation R Study: design and cohort update 2010

The Generation R Study is a population-based prospective cohort study from fetal life until young adulthood. The study is designed to identify early environmental and genetic causes of normal and abnormal growth, development and health during fetal life, childhood and adulthood. The study focuses on four primary areas of research: (1) growth and physical development; (2) behavioural and cognitive development; (3) diseases in childhood; and (4) health and healthcare for pregnant women and children. In total, 9,778 mothers with a delivery date from April 2002 until January 2006 were enrolled in the study. General follow-up rates until the age of 4 years exceed 75%. Data collection in mothers, fathers and preschool children included questionnaires, detailed physical and ultrasound examinations, behavioural observations, and biological samples. A genome wide association screen is available in the participating children. Regular detailed hands on assessment are performed from the age of 5 years onwards. Eventually, results forthcoming from the Generation R Study have to contribute to the development of strategies for optimizing health and healthcare for pregnant women and children.

High-altitude disorders: pulmonary hypertension: pulmonary vascular disease: the global perspective

Globally, it is estimated that > 140 million people live at a high altitude (HA), defined as > 2,500 m (8,200 ft), and that countless others sojourn to the mountains for work, travel, and sport. The distribution of exposure to HA is worldwide, including 35 million in the Andes and > 80 million in Asia, including China and central Asia. HA stress primarily is due to the hypoxia of low atmospheric pressure, but dry air, intense solar radiation, extreme cold, and exercise contribute to acute and chronic disorders. The acute disorders are acute mountain sickness (also known as soroche), HA cerebral edema, and HA pulmonary edema (HAPE). Of these, HAPE is highly correlated with acute pulmonary hypertension. The first chronic syndrome described in HA dwellers in Peru was chronic mountain sickness (Monge disease), which has a large component of relative hypoventilation and secondary erythrocytosis. The prevalence of chronic mountain sickness in HA dwellers ranges from 1.2% in native Tibetans to 5.6% in Chinese Han; 6% to 8% in male residents of La Paz, Bolivia; and 15.6% in the Andes. Subacute mountain sickness is an exaggerated pulmonary hypertensive response to HA hypoxia occurring over months, most often in infants and very young children. Chronic pulmonary hypertension with heart failure but without hypoventilation is seen in Asia. Not only does HA pulmonary hypertension exact health consequences for the millions affected, but also the mechanisms of disease relate to pulmonary hypertension associated with multiple other disorders. Genetic understanding of these disorders is in its infancy.

Genetic associations with mountain sickness in Han and Tibetan residents at the Qinghai-Tibetan Plateau

BACKGROUND

Acute (AMS) and chronic (CMS) mountain sicknesses are illnesses that occur among humans visiting or inhabiting high-altitude environments, respectively. Some individuals are genetically less fit than others when stressed by an extreme high-altitude environment. Seven blood physiological parameters and five genetic polymorphisms were studied in Han patients with AMS and Tibetan patients with CMS.

METHODS

We compared 98 AMS patients with 60 Han controls as well as 50 CMS patients with 36 Tibetan controls. The genetic loci studied are ACE I/D (rs4340), AGT M235T (rs699), AGTR1 A1166C (rs5186), GNB3 A(-350)G (rs2071057) and APOB A/G (rs693).

RESULTS

All physiological parameters (RBC, HCT, Hb, SaO(2), HR, and BPs/d) studied significantly changed in the CMS patients while SaO(2) and HR changed in the AMS Han patients compared to their controls. The ACE D and AGT 235M alleles were found to be significantly associated with AMS and CMS, respectively, while a significantly high incidence of the G-protein (GNB3) (-350)A allele was found in the AMS patients. ACE (I/D) was significantly associated with HR in CMS patients while the AGT M235T was significantly associated with SaO(2) and BPs/d in AMS patients. APOB A/G was significantly associated with BPs/d in AMS and HR in CMS patients.

CONCLUSION

AMS and CMS share very similar genetic results for the ACE I/D and AGT M235T polymorphisms indicating that these mutations have an effect on both illnesses.

Angiotensin-converting enzyme genotype and arterial oxygen saturation at high altitude in Peruvian Quechua

The I-allele of the angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism has been associated with performance benefits at high altitude (HA). In n = 142 young males and females of largely Quechua origins in Peru, we evaluated 3 specific hypotheses with regard to the HA benefits of the I-allele: (1) the I-allele is associated with higher arterial oxygen saturation (Sa(O(2))) at HA, (2) the I-allele effect depends on the acclimatization state of the subjects, and (3) the putative I-allele effect on Sa(O(2)) is mediated by the isocapnic hypoxic ventilatory response (HVR, l/min(1)/% Sa(O(2))(1)). The subject participants comprised two different study groups including BLA subjects (born at low altitude) who were lifelong sea-level residents transiently exposed to hypobaric hypoxia (<24 h) and BHA subjects (born at HA) who were lifelong residents of HA. To control for the possibility of population stratification, Native American ancestry proportion (NAAP) was estimated as a covariate for each individual using a panel of 70 ancestry-informative molecular markers (AIMS). At HA, resting and exercise Sa(O(2)) was strongly associated with the ACE genotype, p = 0.008 with approximately 4% of the total variance in Sa(O(2)) attributed to ACE genotype. Moreover, I/I individuals maintained approximately 2.3 percentage point higher Sa(O(2)) compared to I/D and D/D. This I-allele effect was evident in both BLA and BHA groups, suggesting that acclimatization state has little influence on the phenotypic expression of the ACE gene. Finally, ACE genotype was not associated with the isocapnic HVR, although HVR had a strong independent effect on Sa(O(2)) (p = 0.001). This suggests that the I-allele effect on Sa(O(2)) is not mediated by the peripheral control of breathing, but rather by some other central cardiopulmonary effect of the ACE gene on the renin-angiotensin-aldosterone system (RAAS).