| Backgrounds and objectives:High altitude polycythemia(HAPC) is one kind of chronic high altitude disease commonly seen at high altitude areas. The main characteristics of HAPC is excessive erythropoiesis, and the hemoglobin(Hb) in blood is significantly increased as well as elevated haematocrit, which cause slow blood flow, erythrocyte sedimentation, microcirculation dysfunction, severe hypoxemia, eventually leading to injuries in multiple organs and multi-systems.Both high altitude natives and high altitude immigrants would be affected by HAPC, but the incidence of HAPC in these groups showed significant differences. Epidemiological studies showed that prevalence of HAPC increased with increasing altitude. At the same altitude, the incidence of HAPC in high altitude immigrants was significantly higher than that in high altitude natives, and the incidence in male was significantly higher than that in females. The HAPC diagnostic criteria were as follows: Males Hb≥210 g / L, females Hb≥190 g / L.The main reason of HAPC is chronic hypoxia, while this is not the only factor. Surveys revealed that even Han immigrants who had similar diet, living and working conditions, showed no differences in age or lifestyles at areas with the same altitude, only part of Han immigrants developed HAPC, while another part did not, suggesting that genetic factors may contribute to the development of HAPC in Han Chinese population.According to preliminary results of this study, as well as literature reports, we mainly selected polymorphisms sites of candidate genes in hypoxia inducible factor signaling pathway, genes associated with energy metabolism and genes related to inflammatory factors, which were evaluated to assess the correlation between HAPC risks in Han Chinese population. Moreover, we analyzed gene- gene interactions based polymorphisms of candidate genes, and constructed the best model to predict HAPC in Han Chinese population.Materials and methodsTaking the ratio of 1: 1, we screened 234 HAPC patients and 250 subjects of healthy controls in male Han Chinese population above the altitude of 4,000 meters. Basic information of samples were collected, including age, native place, smoking and drinking status, as well as clinical characteristics including systolic blood pressure(SBP), diastolic blood pressure(DBP), arterial oxygen saturation(Sa O2), heart rate(HR), height and weight, et al. Multiple regression analysis was applied to screen factors affected Hb in HAPC group. Polymorphism sites belongs to multiple genes were screened according to our initial findings and literature reports, genotyping methods based polymerase chain reaction(PCR) were applied including PCR product direct sequencing, agarose gel electrophoresis, high resolution melting curve(HRM) analysis, restriction fragment length polymorphism(RFLP), next-generation sequencing and ligase detection reaction(LDR) to obtain genotypes of polymorphisms in genes mentioned above. Distribution of genotypes and alleles in HAPC and the healthy control group were analyzed by Chi-square test, and one-way ANOVA were applied to evaluate genotype-phenotype correlation. Taking genotypes data of HAPC and healthy control group together, generalized multifactor dimensionality reduction(GMDR) and multifactor dimensionality reduction(MDR) were applied to analyze gene- gene interaction plus logistic regression analysis to construct the best predictive genetic model of HAPC in Han Chinese population.Results1. Compared with the healthy control group, Sa O2 of HAPC patients significantly decreased, while HR, DBP and BMI markedly increased, indicating that HAPC patients expressed severe hypoxiema, and heart function of HAPC patients might be injured.2. Hb in HAPC patients was negatively associated with Sa O2 and positively associated with HR, DBP and BMI.3. At the level of α=0.05, multiple stepwise regression was applied to evaluate effect of Sa O2,HR,DBP and BMI on Hb in HAPC group. The equation was as follows: Hb=265.772+0.221*DBP-0.691*Sa O2. In HAPC group, Hb was affected greatest by Sa O2, followed by DBP.4. In HAPC group, Hb was not associated with smoking or drinking status, while in healthy control group, Hb in drinking only status was higher than that in smoking only status, and Hb in other status showed no differences.5. D/D genotype of ACE gene might be false genotyped, hence D/D genotype should be evaluated again. 55 D/D genotypes were identified initially in this research, and 6 D/D genotypes were identified as I/D genotypes by second analysis. The ratio of D/D genotype identified as I/D genotype was 11.3% in this research.6. Rs11549465 and rs11549467 in HIF-1α associated with transcriptional activities, rs726354 in SENP1 gene and rs3025033 in VEGFA gene associated with HAPC in Andeans showed no association with HAPC development in Han Chinese population.7. Codominant model and dominant model analysis indicated that distribution of three genotypes of rs8065364 in CARD14 gene showed significant differences in HAPC and healthy control group. The codominant model analysis revealed that C/T vs T/T(OR=1.61,95%CI=1.10-2.38),C/C vs T/T(OR=2.19,95%CI=1.23-3.89),p=0.006. The dominant model analysis revealed that C/T+C/C vs T/T(OR=1.74, 95%CI=1.21-2.49), p=0.003. For polymorphism of rs9842536 in ULK4 gene, the distribution of C and T alleles in HAPC and healthy control group showed remarkable difference(p=0.024), and the T allele was a protective factor of HAPC in Han Chinese population(OR=0.73, 95%CI=0.56-0.96). For polymorphism of rs8065364 in CARD14 gene, the distribution of C and T alleles in HAPC and healthy control group showed remarkable difference(p=0.0009), and the C allele was a risky factor of HAPC in Han Chinese population(OR=1.59, 95%CI=1.21-2.08).8. The C/T genotype in polymorphism of rs8065686 in HDAC5 gene was a risky factor of HAPC in Han Chinese population(OR=1.71, 95%CI=1.11-2.62), while allele frequency analysis indicated that alleles of C and T showed no differences in distribution between HAPC and healthy control group. The C/T genotype in polymorphism of rs2227956 in HSPA1 L gene was a risky factor of HAPC in Han Chinese population(OR=1.62, 95%CI=1.10-2.39), while allele frequency analysis indicated that alleles of C and T showed no differences in distribution between HAPC and healthy control group.9. Distribution of three genotypes of rs1385129 in Glut1 gene showed significant differences in HAPC and healthy control group, compared with G/G genotype, A/G genotype was a protective factor of HAPC in Han Chinese population(OR=0.63,95%CI=0.43-0.94), and allele analysis indicated that the A allele was a protective factor of HAPC in Han Chinese population(OR=0.69,95%CI=0.51-0.92). Distribution of three genotypes of rs2086856 showed significant differences in HAPC and healthy control group, compared with G/G genotype, A/A genotype was a risky factor of HAPC in Han Chinese population(OR=1.84,95%CI=1.08-3.13), and allele analysis indicated the A allele was a risky factor of HAPC in Han Chinese population(OR=1.42, 95%CI=1.09-1.83). Distribution of three genotypes of rs841853 showed no differences in HAPC and healthy control group, and allele analysis indicated the G allele was a risky factor of HAPC in Han Chinese population(OR=1.45, 95%CI=1.06-1.98).10. Distribution of three genotypes of polymorphism rs2767035 in PDHX gene between HAPC and healthy control group showed significant differences, compared with T/T genotype, the C/T genotype was a risky factor of HAPC in Han Chinese population(OR=1.68, 95%CI=1.15-2.45), while allele analysis indicated no differences were observed in distribution of C and T alleles in HAPC and healthy control group. Distribution of three genotypes of rs3758682 in LDHA gene showed no differences in HAPC and healthy control group, and allele analysis indicated the c allele was a risky factor of HAPC in Han Chinese population(OR=1.31,95%CI=1.00-1.71).11. Distribution of three genotypes of polymorphisms rs2779212 and rs2015353 showed no differences in HAPC and healthy control group. Allele analysis indicated that the C allele of rs2779212 was a protective factor of HAPC in Han Chinese population(OR=0.72, 95%CI=0.53-0.96), and the A allele of rs2015353 was a risky factor of HAPC in Han Chinese population(OR=1.56,95%CI=1.06-2.28). No differences was observed in distribution of three genotypes of rs6818140 in UCP1 gene between HAPC and healthy control group, and allele analysis indicated that the A allele was a protective factor of HAPC in Han Chinese population(OR=0.69,95%CI=0.49-0.97).12. Gene-gene interaction analysis indicated that the synergistic relationship between rs726354 and rs3025033 plus rs8065364 may be involved in the development of HAPC in Han Chinese population. Taken genotypes data of EPAS1 and polymorphisms data in energy metabolism genes as well as inflammatory factors related gene together into analysis, the final results of this study showed that combination of polymorphism rs8065364 in CARD14 gene and polymorphism rs2086856 in Glut1 gene may be the best model to predict HAPC in Han Chinese population, and the negative effect of interaction between these two polymorphisms may contribute to the development HAPC in Han Chinese population. Taken the rs2086856 A/A genotype and rs8065364 of the T/T genotype as a reference, individuals carrying A/G genotype of rs2086856 and C/T genotype of rs8065364 may increase risk of HAPC 1.98 times in Han Chinese population.ConclusionGenetic susceptibility are existing in HAPC among Han Chinese population, and this genetic susceptibility may be present in genes in the signaling pathways of energy metabolism, inflammatory signaling pathways and regulation of oxygen sensing signaling pathways.C allele in SNP rs8065364 of CARD14, A allele in SNP rs2086856 and G allele in SNP rs841853 of Glut1, C allele in SNP rs3758682 of LDHA and A allele in SNP rs2015353 of ADORA2 B are risky factors of HAPC in Han Chinese population. T allele in SNP rs9842536 of ULK4, A allele in SNP rs1385129 of Glut1, C allele in SNP rs2779212 of ADORA2 B, and A allele in SNP rs6818140 of UCP1 are protective factors of HAPC in Han Chinese population.The synergetic relationship between rs726354, rs3025033 plus rs8065364, and the redundant relationship between rs8065364 and rs2086856 may be associated with HAPC in Han Chinese population.Interaction between genes belong to signaling pathways of energy metabolism, inflammatory signaling pathways and regulation of oxygen sensing signaling pathways may be involved in the development of HAPC in Han Chinese population. |
PDF Full Text Request