Zongzhe Li

Polymorphism of tumor necrosis factor alpha (TNF-alpha) gene promoter, circulating TNF-alpha level, and cardiovascular risk factor for ischemic stroke

BackgroundTumor necrosis factor-α (TNF-α) is one of the most typical pro-inflammatory cytokines with both beneficial and destructive properties for the central nervous system. Increasing evidences have demonstrated the important role of TNF-α in the development of ischemic stroke, but studies examining the possible association with stroke or direct functional effects of polymorphisms in TNF-α have been contradictory.FindingsIn this study, a 2-kb length of the proximal promoter of the TNF-α was screened and four polymorphisms were investigated in the case–control study. Our data confirmed the association between -308G/A variant with stroke in 1,388 stroke patients and 1,027 controls and replicated in an independent population of 961 stroke patients and 821 controls (odds ratio (OR) = 1.34, 95% confidence interval (CI) =1.02 to 1.77 and OR = 1.56, 95% CI = 1.09 to 2.23, respectively). To reconcile the association between polymorphisms and stroke and to give a comprehensive picture of the genetic architecture of this important gene, we performed a meta-analysis of 15 published studies in an Asian population. Our results demonstrated an association between rs1800629 and ischemic stroke (OR = 1.43, 95% CI = 1.21 to 1.69). Another meta-analysis results of 14 studies demonstrated that ischemic stroke patients have higher serum TNF-α level than the control subjects (standardized mean difference (SMD) = 2.33, 95% CI = 1.85 to 2.81). In vitro evaluation of potential interaction between variants of the TNF-α gene (−308G/A, -857C/T, and -1031T/C) demonstrated that these three polymorphisms could interact together to determine the overall activity of the TNF-α gene.ConclusionsThese findings strongly implicate the involvement of TNF-α in the pathogenesis of stroke.

Association Analysis of Polymorphisms in ROCK2 with Cardiovascular Disease in a Chinese Population

Background Rho-kinase (ROCK) has been shown to play an important role in cardiovascular disease such as coronary artery disease (CAD) and hypertension. Recently, common variants of ROCK2 have been reported to influence blood pressure, but the relationship between common ROCK2 variants and cardiovascular disease has not been extensively studied in the Chinese population. Methods To derive a more precise estimation of their relationship, we screened for the common variants by direct sequencing of all exons of ROCK2, and then we performed genetic association analyses in a CAD case–control study, including a total of 1344 cases and 1267 ethnically and geographically matched controls. Results Unconditional logistic regression showed that no significant association between common variants in the coding region of ROCK2 and CAD was observed in our study (for rs978906, OR = 0.92, 95% CI 0.72–1.20 and P = 0.63; for rs2230774, OR = 0.90, 95% CI 0.70–1.16 and P = 0.47; for rs56304104, OR = 0.97, 95% CI 0.70–1.31 and P = 0.83; respectively). Conclusions The relationship between the ROCK2 polymorphisms and cardiovascular disease risk cannot be entirely discounted and warrants further evaluation in a large population.

Novel URAT1 mutations caused acute renal failure after exercise in two Chinese families with renal hypouricemia.

Renal hypouricemia (RHUC), as an infrequent hereditary disease, is associated with severe complications such as exercise-induced acute renal failure (EIARF). Loss-of-function mutations in urate transporter gene URAT1 (Type 1) and in glucose transporter gene GLUT9 (Type 2) are major causes of this disorder. In this study, URAT1 and GLUT9 were screened in two uncorrelated families from mainland China and a total of five mutations were identified in exons, including two novel heterozygous URAT1 mutations. In four members of the first family, c.151delG (p.A51fsX64) in exon 1 was detected, which resulted in a frameshift and truncated the original 553-residue-protein to 63 amino acid protein. A missense mutation c.C1546A (p.P516T) in exon 9 in GLUT9 was revealed in the second family, which caused a functional protein substitution at codon 516. These two novel mutations were neither identified in the subsequent scanning of 200 ethnically matched healthy control subjects with normal serum UA level nor in a 1000 genome project database. Thus our report identifies two novel loss-of-function mutations (c.151delG in URAT1 and p.P516T in GLUT9) which cause RHUC and renal dysfunction in two independent RHUC pedigrees.

Novel homozygous deletion of segmental KAL1 and entire STS cause Kallmann syndrome and X-linked ichthyosis in a Chinese family.

Kallmann syndrome (KS) is a genetically heterogeneous disease characterised by hypogonadotrophic hypogonadism in association with anosmia or hyposmia. This condition affects 1 in 10 000 men and 1 in 50 000 women. Defects in seventeen genes including KAL1 gene contribute to the molecular basis of KS. We report the clinical characteristics, molecular causes and treatment outcome of two Chinese brothers with KS and X‐linked ichthyosis. The phenotypes of the patients were characterised by bilateral cryptorchidism, unilateral renal agenesis in one patient but normal kidney development in another. The patients had low serum testosterone, follicle‐stimulating hormone and luteinising hormone levels and a blunt response to the gonadotrophin‐releasing hormone stimulation test. After human chorionic gonadotrophin treatment, the serum testosterone levels were normalized, and the pubic hair, penis length and testicular volumes were greatly improved in both of the patients. The two affected siblings had the same novel deletion at Xp22.3 including exons 9‐14 of KAL1 gene and entire STS gene. Our study broadens the mutation spectrum in the KAL1 gene associated with KS and facilitates the genetic diagnosis and counselling for KS.

Variants of genes encoding collagens and matrix metalloproteinase system increased the risk of aortic dissection

Aortic dissection (AD) is a devastating, heterogeneous condition of aorta. The homeostasis between collagens and matrix metalloproteases (MMPs)/tissue inhibitors of MMPs (TIMPs) system in the extracellular matrix plays an important role for structure and functions of aorta. However, our knowledge on association between variants of genes in this system and pathogenesis of AD is very limited. We analyzed all yet known coding human genes of collagens (45 genes), MMPs/TIMPs (27 genes) in 702 sporadic AD patients and in 163 matched healthy controls, by using massively targeted next-generation and Sanger sequencing. To define the pathogenesis of potential disease-causing candidate genes, we performed transcriptome sequencing and pedigree co-segregation analysis in some genes and generated Col5a2 knockout rats. We identified 257 pathogenic or likely pathogenic variants which involved 88.89% (64/72) genes in collagens-MMPs/TIMPs system and accounted for 31.05% (218/702) sporadic AD patients. In them, 84.86% patients (185/218) carried one variant, 12.84% two variants and 2.30% more than two variants. Importantly, we identified 52 novel probably pathogenic loss-of-function (LOF) variants (20 nonsense, 16 frameshift, 14 splice sites, one stop-loss, one initiation codon) in 11.06% (50/452) AD patients, which were absent in 163 controls (P=2.5×10−5). Transcriptome sequencing revealed that identified variants induced dyshomeostasis in expression of collagens-TIMPs/MMPs systems. The Col5a2−/− rats manifested growth retardation and aortic dysplasia. Our study provides a first comprehensive map of genetic alterations in collagens-MMPs/TIMPs system in sporadic AD patients and suggests that variants of these genes contribute largely to AD pathogenesis.

A novel nonsense mutation in LMNA gene identified by Exome Sequencing in an atrial fibrillation family.

Genetic factor plays an important role in cardiac arrhythmias. Several loci have been identified associated with this disease. However, they only explained parts of it and more genes and loci remain to be identified. In present study, we recruited a four generation family from the north of China. Four members of this family were diagnosed with atrial fibrillation by electrocardiogram (ECG). We used Exome Sequencing and Sanger sequencing to explore the candidate mutation for cardiac arrhythmia in this family. A nonsense mutation (c.G1494A, p.Trp498Ter) in the LMNA gene were identified as the candidate mutation. This variant is a novel mutation and has not yet been reported for any actual databases. This novel mutation co-segregated exactly with the disease in this family. Meanwhile, it was not detected in 524 control subjects of matched ancestry. According to structural model prediction, the mutation is expected to affect the Lamin Tail Domain (LTD) of lamin A/C protein. So the nonsense mutation discovered in the family probably was a novel mutation associated with familial atrial fibrillation. This discovery expands the mutation spectrum of LMNA and indicates the importance of LMNA in AF.

A targeted sequencing approach to find novel pathogenic genes associated with sporadic aortic dissection

Aortic dissection (AD) is a heterogeneous genetic disease of the aorta with high mortality and poor prognosis. However, only few genetic causes of AD have been explored till date. After conducting a broad literature review focused on identifying potential pathogenic pathways, we designed a panel containing 152 AD-associated genes to conduct massively parallel targeted next-generation sequencing of 702 sporadic aortic dissection patients and 163 matched healthy controls. After validation by Sanger sequencing, we identified 21 definitely pathogenic and 635 likely pathogenic variants in 61.25% (430/702) of patients. In these patients, 34.88% (150/430) harbored more than one variant that was either definitely or likely to be pathogenic. Among the candidate genes, we identified 546 likely pathogenic variants in 47.72% (335/702) of patients. Importantly, we identified 94 loss-of-function (LOF) variants in 45 genes in AD patients, but only five LOF variants in the controls (P=1.34×10−4). With a burden test, we highlighted RNF213 as an important new gene for AD pathogenesis. We also performed transcriptome sequencing of human aorta tissues to evaluate the expression levels of these newly identified genes. Our study has compiled a comprehensive genetic map of sporadic AD in the Han Chinese population. We believe it will facilitate risk predicting and genetic diagnosis of this severe disease in the future.

Mutation profiles and clinical characteristics of Chinese males with isolated hypogonadotropic hypogonadism

OBJECTIVE To investigate the mutation profiles and clinical characteristics of Chinese males with isolated hypogonadotropic hypogonadism (IHH) and discover new pathogenic genes that cause IHH. DESIGN A gene panel, including 31 known IHH genes and 52 candidate genes, was used to perform semiconductor next-generation sequencing. SETTING University hospital. PATIENTS One hundred thirty-eight sporadic male IHH patients and 10 IHH families; 100 healthy men with normal fertility served as control subjects. INTERVENTIONS(S) None. MAIN OUTCOME MEASURE(S) Targeted next-generation sequencing, polymerase chain reaction and sequencing, pedigree analysis, and bioinformatics analysis. RESULT(S) Variants were distributed uniformly throughout 52 genes (52/83, 62.65%), including 16 (16/31, 51.61%) causal genes and 36 (36/52, 69.23%) candidate genes. Six new pathogenic variants and 52 likely pathogenic variants were identified in 16 genes known to cause nIHH/KS (normosmic IHH/Kallmann syndrome). In the 148 probands, PROKR2 (22/148, 14.86%), CHD7, FGFR1, and KAL1 had high mutation rates, and 8.78% (13/148) of the patients carried at least two variants in known genes. In addition, variants were identified in 36 candidate genes, and EGFR, ERBB4, PAX6, IGF1, SEMA4D, and SEMA7A should be prioritized for further research and genetic testing in IHH. CONCLUSION(S) The mutation frequency of IHH-causal genes in Chinese HAN males was different from the data reported in white populations. Oligogenic inheritance was a common phenomenon in IHH. Our study expands the mutation profile for IHH, and the new likely pathogenic genes identified in our study warrant further research in GnRH neuronal networks.