| Background and Objective:Multiple endocrine neoplasia type Ⅱ (MEN2; MIM171400) is an autosomal dominant neuroendocrine neoplasia predisposition syndrome characterized by variable penetrance of medullary thyroid carcinoma (MTC), pheochromocytoma (PHEO), and hyperparathyroidism (HPT). It can be distinguished as three different syndromes:multiple endocrine neoplasia type2A (MEN2A), MEN2B, and familial medullary thyroid carcinoma (FMTC). MEN2A is characterized clinically by the presence of medullary thyroid carcinoma, bilateral pheochromocytoma, and primary hyperparathyroidism within a single patient or family. Previous study showed that MEN2A presents in55%of MEN2. FMTC is associated with a very low incidence of other endocrinopathies, which accounts for35%～40%of MEN2. MEN2B is an association of MTC, pheochromocytoma, and mucosal neuroma which is responsible for only5%～10%of MEN2. This disorder is usually caused by germline mutations of the rearranged during transfection protooncogene gene(RET; MIM164761) or the neurotrophic tyrosine kinase receptor type1gene(NTRK1; MIM191315). MEN2starts hidden and the duration is long and slow, so that diagnosis and treatment are easy to be delayed. MEN2genetic screening provides a major tool for the preclinical diagnosis and early treatment of unsuspected affected family members. Genetic test is the gold standard, and a positive result is the sole indication for recommending surgery. Further studies of the gene functions can make gene therapy for MEN2possible. To investigate the genetic cause in a Chinese Han family with MEN2A and the genotype-phenotype correlations, nine members belonging to3generations of MEN2A family with5affected subjects underwent genetic analysis.Method:Blood was collected from9members of this family, including5patients. Metaphase chromosome preparation was performed on a72-hour harvest of phytohemagglutinin (PHA)-stimulated peripheral blood lymphocytes of the proband and her sister, standard karyotyping of Giemsa-trypsin-Giemsa (GTG) banded chromosomes from lymphocytes was performed according to standard procedures. Direct sequencing of the polymerse chain reaction (PCR) products cover all coding regions and intron/exon boundaries of RET and NTRK1gene was conducted in proband. Mutation co-segregated analysis was performed in the Chinese Han family with MEN2A, and RET Cys634Arg was detected in100normal controls.Results:In two cases, GTG banded chromosome analysis had been carried and revealed normal female karyotypes (46, XX). Sequence analysis of the whole coding region of the RET and NTRK1genes discovered nine nucleotide variants(RET:c.1296G>A, Ala432Ala; c.1900T>C, Cys634Arg; c.2071G>A, Gly691Ser; IVS12+47C>T; C.2712C>G, Ser904Ser; NTRK1:-5G>A; c.1187C>T, Ser396Leu; IVS16-4delA; IVS18+6C>T) including4novel variants (RET: c.1296G>A, Ala432Ala; C.2712C>G, Ser904Ser; NTRK1:c.1187C>T, Ser396Leu; IVS18+6C>T). Extended analysis of the family members revealed that Cys634Arg mutation co-segregated with MEN2A in this Chinese Han family and this mutation was absent in100normal controls. Five carriers were clinically affected and all of them underwent surgery. Only one family member positive for the RET Cys634Arg mutation, a36-year-old man (Ⅱ:7) was asymptomatic and had no evidence of disease by Doppler ultrasound.Conclusion:GTG banded chromosome analysis and gene mutation analysis were performed in the Chinese Han family with MEN2A, nine nucleotide variants (RET:c1296G>A, Ala432Ala; c.1900T>C, Cys634Arg; c.2071G>A, Gly691Ser; IVS12+47C>T; c.2712C>G, Ser904Ser; NTRK1:-5G>A; C.1187C>T, Ser396Leu; ⅣS16-4delA; IVS18+6C>T) were found in subsequent sequencing analysis of the RET and NTRK1genes, and Cys634Arg mutation is a pathogenic mutation. A Cys634Arg carrier (Ⅱ:7) presented no clinical symptoms suggestive of MEN2or MTC, suggesting that MEN2is a disease with incomplete penetrance or delay the onset age. These finding may provide help to understand the relationship between genotype and phenotype of MEN2A further, and also has implications for genetic counseling and prenatal diagnosis of MEN2A. Background and Objective:Chronic obstructive pulmonary disease (COPD; MIM606963) is a common, complex disease associated with significant and increasing morbidity and mortality. The genetic architecture of COPD is likely to be complex, with the contribution of multiple genes and environmental factors interaction. Cigarette smoking is the primary risk factor for COPD. However, the susceptibility to COPD is different between individuals. Study of the COPD pathogenesis is helpful to develop new drug target and promote the earily diagnosis and therapy of COPD.Advances in Human Genomic Project and HapMap offer an opportunity to study the genetic architecture of COPD from the gene and genomic level. Genome-wide association study (GWAS) is a method using millions of single-nucleotide polymorphisms (SNPs) in different individuals to see if any variant is associated with a trait. It has been applied on COPD genetic study as a frontier and effective research method using in complex diseases. So far GWAS in COPD has acquired some positive results, but larger-scale studies in different populations are warranted to document the conclusive evidence of the effects of these positive results on COPD risk.Recently, genome-wide association study (GWAS) revealed a statistically significant association between COPD and several gene variants including the iron-responsive element-binding protein2gene (IREB2; MIM147582) rs2568494, the family with sequence similarity13member A gene (FAM13A; MIM613299; rs2869967and the X-ray repair cross-complementing protein5gene (XRCC5; MIM194364) rs3821104in non-Asian populations. To determine the association between these variants and COPD in Chinese Han population, we screened DNA of Chinese COPD patients and normal controls from Mainland China.Method:Direct sequencing of the polymerse chain reaction (PCR) products was conducted in two hundred and seventy-five unrelated Chinese Han COPD patients and434sex, age and ethnicity matched normal controls to identify the association between these genes and polymorphisms and COPD. Sequencing results were analysis by using the Assign3.5, MT Navigator and DNAstar software. Hardy-Weinberg equilibrium was performed as to ascertain the normal heterogeneity of the population. SPSS16.0software was applied in case-control study to find out the association between gene variants and COPD.Results:The genotype frequencies of all tested single nucleotide polymorphisms (SNPs) were in accordance with the Hardy-Weinberg equilibrium in controls. Statistically significant association with COPD compared to normal controls was observed in genotypic distributions (χ2=6.319, P=0.042for rs2869967;χ2=6.062, P=0.048for rs3821104) and allele distributions (χ2=4.014, P=0.045for rs2869967; χ2=5.607, P=0.018for rs3821104) for the FAM13A rs2869967and XRCC5rs3821104, consistent with the prior report. However, there was no significant association between the IREB2rs2568494variant and COPD phenotype (χ2=0.590, P=0.744for genotypic distribution;χ2=0.034, P=0.854for allele distribution).Conclusion:Statistically significant association with COPD compared to normal controls was observed in genotypic distributions (χ2=6.319, P=0.042for rs2869967;χ2=6.062, P=0.048for rs3821104) and allele distributions (χ2=4.014, P=0.045for rs2869967;χ2=5.607, P=0.018for rs3821104) for the FAM13A rs2869967and XRCC5rs3821104, although no significant association was found for IREB2rs2568494variant. The result suggests there are different pathogenic and genetic model in COPD between Chinese Han population and non-Asian populations. The discovery of genetic risk variants, such as those in FAM13A and XR.CC5, may contribute to the eventual development of the early warning method and new therapeutic approaches to COPD. |
PDF Full Text Request