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Objective: To identify the genetic variants of angiotensin I converting enzyme 2 (ACE2) gene in a Chinese population and to determine whether the ACE2 gene polymorphisms are associated with essential hypertension (EH)., Methods: Seven hundred and forty-five patients with EH and 362 normal blood pressure controls were included in the study to assess the contribution of polymorphism of ACE2 gene. Direct DNA sequencing was performed to detect the single nucleotide polymorphisms (SNPs) in 20 subjects who were randomly selected from the EH patients., Results: One SNP named G8790A located in the 4th base of the third intron was found in the 20 patients. The genotyping data indicate that the A allele frequency in male EH patients complicated with cardiac incompetence(55%) is significantly different from that in the control group(43.3%)(P<0.01). The A allele frequency in female patients with cardiac incompetence (56.1%) is higher than that in the controls (50.5%), but the difference does not reach statistical significance., Conclusion: The G8790A polymorphism may be related to the essential hypertension with cardiac incompetence in Chinese population. Additional investigation will be need to confirm the association.

Objective: To identify the genetic variants of angiotensin II type 1 receptor (AT1) gene in a population of Han ethnicity in east China and to determine whether the AT1 gene polymorphisms are associated with essential hypertension (EH) and coronary heart disease (CHD)., Methods: The detection of single nucleotide polymorphisms (SNPs) was performed in 20 subjects by a direct DNA sequencing. All 213 EH patients, 171 patients of EH with CHD and 200 controls were genotyped by three detected SNPs., Results: Eight positive SNPs were detected in the promoter, exon and 3' untranslated region (3'UTR) of AT1 gene. A case-control study by using a frequent SNP (A-153G) in the promoter region, showed a significant increase in allele frequency of G-153 in the subjects of EH complicated with CHD (17.8% vs 11.5% for normal controls, P < 0.05). The SNP A1166C, which has been widely studied, manifested no difference in the three groups., Conclusion: A polymorphism in the promoter region (A-153G) of AT1 gene might be involved in the development of EH and CHD in Han ethnicity population in east China.

Objective: To identify single nucleotide polymorphisms (SNP) in the regulatory and coding regions of human kynureninase (KYNU) gene in a hypertensive candidate chromosomal region 2q14-q23 of Han Chinese, and to investigate the relationship between polymorphisms in KYNU and essential hypertension., Methods: The SNPs in the promoter region and exons of the KYNU gene were detected by direct DNA sequencing. Genotyping of the nonsynonymous Lys412Glu (A/G) polymorphism was performed by DHPLC technology in 456 hypertensive patients and 430 normal controls., Results: Sixteen SNP were identified in the KYNU gene, including 6 in the regulatory region and 2 in the coding region (both of them lead to substitution of amino acid). Significant differences between hypertensive patients and normal controls were observed for the distribution of alleles (chi(2) = 6.693, P = 0.035) and genotypes (chi(2) = 4.188, P = 0.041) of the Lys412Glu polymorphism in all subjects, and for the distribution of alleles in the subgroup of men (chi(2) = 4.424, P = 0.035)., Conclusion: The Lys412Glu polymorphism of the KYNU gene in a hypertensive candidate chromosomal region is associated with essential hypertension in Han Chinese.

Objective: To identify single nucleotide polymorphisms (SNP) of the angiotensin II type 2 receptor (AGTR2) gene, and to determine whether the AGTR2 polymorphisms are associated with essential hypertension in a male Chinese population., Methods: Direct DNA sequencing was performed in 20 subjects. 96 male hypertensive patients and 107 normal controls were included to assess the contribution of the SNP of AGTR2 gene to hypertension., Results: Seven SNP of the AGTR2 gene were identified, of which 4 were reported for the first time. A case-control study including two polymorphisms (A1675G and T1334C) showed a significant increase in the A1675 allele frequency among male hypertensive subjects as compared with normotensive subjects (49.0% vs 34.6%, P < 0.05)., Conclusion: The AGTR2 A1675G polymorphism might be involved in the development of essential hypertension in male Chinese.

Objective: To evaluate the relationship of six single nucleotide polymorphisms(SNPs) and their haplotypes of angiotensinogen(AGT) gene to essential hypertension(EH) in Chinese Han population., Methods: The genotypes in 185 patients with EH and 185 healthy controls were determined by the method of ABI PRISM SNaPshot Multiplex Kit using six AGT gene polymorphisms at position -217(G/A), -152(G/A), -20(A/C) and -6(G/A) in the promoter region and T174M, M235T in exon 2., Results: The distribution of AGT genotypes and alleles frequencies showed no significant difference between the group of EH and group of controls (P>0.05). However, haplotype analysis revealed that H4 haplotype frequency, which included -152A, -20C, -6A and 235T alleles, was significantly increased in the group of EH (P<0.05)., Conclusion: G-152A, A-20C, G-6A and M235T polymorphisms of AGT gene might play an important role in the occurrence of EH in Chinese Han population.

Objective: To identify the single nucleotide polymorphisms (SNPs) in the regulatory and coding regions of human SCN7A (sodium channel, voltage-gated, type VII, alpha polypeptide) gene and to investigate the association of some of these SNPs with essential hypertension (EH) in Chinese., Methods: The promoter region, exons, as well as part of the introns of SCN7A gene were sequenced by a fluorescent labeling automatic sequencing method to identify and characterize the SNPs in Chinese population. SNP genotyping was performed by PCR-RFLP or direct DNA sequencing in unrelated EH patients and normotensive controls from a Chinese Han population residing in Shanghai area. Case-control studies on seven SNPs were first carried out in 96 patients and 96 normotensive controls. The positive finding was further verified in an extended study containing 288 patients and 288 controls., Results: Thirty-two SNPs were identified through a 13,132 bp sequencing of SCN7A gene. Among them, seven were in regulatory region, ten in coding regions, one in 3'UTR and fourteen in introns. Thirty SNPs were novel SNPs, and a cSNP in exon 18 (SNP021) was associated with hypertension., Conclusion: The SNP021 in the gene SCN7A is associated with essential hypertension of Chinese Han population in Shanghai and the role of SCN7A gene in hypertension deserves to be further analyzed.

Aim: To identify the genetic variants of angiotensin II type 2 receptor (AT2R) gene in a Chinese population and to determine whether the AT2R gene polymorphisms are associated with essential hypertension (EH)., Methods: The detection of single nucleotide polymorphisms (SNPs) was performed in 19 subjects by a direct DNA sequencing. Two hundred fifty patients with EH and 250 nomortensive controls were included in the study to assess the contribution of polymorphism of AT2R gene to hypertension., Results: We identified 9 SNPs in the promoter, intron, exons and 3' untranslated region (3'UTR) of AT2R gene; among them 5 SNPs were novel molecular variants. A case-control study using a most frequent SNP (1334T/C) in the promoter region, showed a significant increase in allele frequency of C1334 in male hypertensive subjects (17.5 % vs 10.3 % for normotensive subjects, P<0.05)., Conclusion: The catalogue of SNPs of AT2R gene in Chinese population showed ethnic difference in DNA sequence variation. A polymorphism in the promoter region (1334T/C) of AT2R gene might be involved in the development of hypertension in Chinese population.

Genes underlie numerous human diseases and traits. Although we have witnessed a great deal of success in identifying disease-susceptible genes, the task remains challenging for most of the complex diseases. This paper reviews evidence for the role of genetic factors in complex diseases, and strategies that can potentially optimize our chance of success in identifying genes involved in complex diseases. Advances in molecular biology, particularly mapping of the human genome, statistical methods that provide more accurate models of complex patterns of inheritance, and advances in basic medical science, which have increased our understanding of disease pathophysiology, will ultimately strengthen the ability of the current generation of genetic epidemiological studies to identify the genetic basis of complex human disorders.

Objective: To screen the gene mutation in beta and gamma subunits of the epithelial sodium channel (ENaC) of a Chinese family, some of whose members are clinically diagnosed as suffering from Liddle syndrome., Methods: Twelve family members were recruited to the study. Among them, two brothers had been clinically diagnosed as suffering from Liddle syndrome. Peripheral blood samples were collected from all members of the family and total genomic DNA was prepared for genetic analysis. Polymerase chain reaction (PCR) was used for amplifying the last exon of beta (codon 513-673) and gamma (codon 503-632) subunits of the ENaC gene. PCR products were purified and subjected to a direct DNA sequence analysis., Results: Genetic analysis of the beta ENaC gene revealed a missense mutation of CCC to CTC at codon 616 in four middle-aged men of the second generation and one young woman of the third generation. There was no mutation of the gamma ENaC gene in any of the individuals examined., Conclusion: Through direct DNA sequencing analysis, we diagnosed the disease present in five members of a Chinese family as Liddle syndrome, and excluded it in some other young offspring suffering from the monogenic disease. Our results provide further evidence that Pro616 is a critical amino acid that has a key role in the inhibition of sodium channel activity.