Polymorphism of Methionine Synthase Gene in Nuclear Families of Congenital Heart Disease

Objective To investigate the relation of methionine synthase (MS) gene variation with congenital heart disease (CHD) phenotype. Methods One hundred and ninety three CHD patients (94 males and 99 females) and their biological parents (nuclear families) in Liaoning Province were selected as the case group, and another 104 normal persons (60 males and 44 females) and their parents without family history of birth defects as the control group. For all subjects the polymorphism of MS gene A2756G locus was examined by PCR-RFLP method. Results In offspring of the control group the frequencies of MS genotype (+/ -) and allele (+) were 10.7% and 5.3%, without existence of homozygote. The MS genotype distribution and allele frequencies of CHD patients and their mothers were not significantly different from the control (P > 0.05). The frequency of allele (+) in case fathers (5.0 %) was apparently lower than that in the control (9.1%, P=0.060), and the odds ratio (OR) was 0.53 (95% CI: 0.25-1.09). There was no difference in parents' genotype combination between the two groups, and in genotype distribution among different types of CHD. Analysis of genetic transmission indicated that mutation allele (+) existed transmission disequilibrium in CHD nuclear families. The percentage of allele (+) transmitted from parents was lower than that allele (-) with OR 0.26 (95% CI: 0.11-0.60). Conclusion MS gene variation in parents is associated with occurrence of CHD in offspring, and mutation allele (+) in parents may be related with the decrease of CHD risk in offspring.

Interaction between maternal 5,10-methylenetetrahydrofolate reductase C677T and methionine synthase A2756G gene variants to increase the risk of fetal neural tube defects in a Shanxi Han population

Background The 5,10-methylenetetrahydrofolate reductase （MTHFR） and methionine synthase （MS） are attractive candidates for screening for risk of neural tube defects （NTDs）. The aim of the current study was to investigate maternal MTHFR and MS polymorphisms and the interaction between them and their influence on children with NTDs in the Shanxi Province of northern China. Methods Fifty-one mothers who previously had children with NTDs constituted the case group and 51 age-matched mothers with children that were unaffected by any birth defects constituted the control group. All subjects were genotyped for MTHFR C677T and MS A2756G polymorphisms. SPSS 11.5 software package was used for all analyses. Results There was a significant difference for MTHFR genotype distribution for one site （C677T） between the case and control groups. The T allele frequencies were significantly higher in the case group than in the control group （55.9% vs. 35.3%, P 〈0.05）. A lack of association was observed for the MS A2756G polymorphism. There was an interaction between the maternal MTHFR C677T genotype and MS A2756G genotype. Conclusion Genetic interaction between MTHFR and MS genes raises the probability of neural tube defects.

Design, Synthesis and Activities of Aziridine Derivatives of N^5-Methyltetrahydrofolate Against Methionine Synthase

Aziridine derivatives of N^5-methyltetrahydrofolate were designed and synthesized based on the mechanism of methionine synthase, and their biological activities were investigated as well. The aziridine derivatives 1 and 6 exhibited superior inhibitory activities（IC50：5.05 and 4.15 μmol/L, respectively） compared to the corresponding chain analogue 4（IC55=24.42 μmol/L）. The results suggest that the aziridine derivatives can get potential activities against nucleophilic methionine synthase.

Vitamin B_(12)-auxotrophy in dinoflagellates caused by incomplete or absent cobalamin-independent methionine synthase genes(metE)

Dinoflagellates are responsible for most marine harmful algal blooms (HABs) and play vital roles in many ocean processes.More than 90% of dinoflagellates are vitamin B_(12) auxotrophs and that B_(12) availability can control dinoflagellate HABs,yet the genetic basis of B_(12) auxotrophy in dinoflagellates in the framework of the ecology of dinoflagellates and particularly HABs,which was the objective of this work.Here,we investigated the presence,phylogeny,and transcription of two methionine synthase genes(B_(12)-dependent metH and B_(12)-independent metE)via searching and assembling transcripts and genes from transcriptomic and genomic databases,cloning 38 cDNA isoforms of the two genes from 14 strains of dinoflagellates,measuring the expression at different scenarios of B_(12),and comprehensive phylogenetic analyses of more than 100 organisms.We found that 1)metH was present in all 58 dinoflagellates accessible and metE was present in 40 of 58 species,2)all metE genes lacked N-terminal domains,3)metE of dinoflagellates were phylogenetically distinct from other known metE genes,and 4)expression of metH in dinoflagellates was responsive to exogenous B_(12) levels while expression of metE was not responding as that of genuine metE genes.We conclude that most,hypothetically all,dinoflagellates have either non-functional metE genes lacking N-terminal domain for most species,or do not possess metE for other species,which provides the genetic basis for the widespread nature of B_(12) auxotrophy in dinoflagellates.The work elucidated a fundamental aspect of the nutritional ecology of dinoflagellates.

Plasma Homocysteine and Gene Polymorphisms Associated with the Risk of Hyperlipidemia in Northern Chinese Subjects

Objective To examine the relationship between occurrence of hyperlipidemia, plasma homocysteine and polymorphisms of methylenetetra hydrofolate reductase （MTHFR） gene and methionine synthase （MS） gene. Methods A total of 192 hyperlipidemia patients were selected and divided into hypercholesterolemia group, hypertriglyceridemia group, and combined hyperlipidemia group. Another 208 normal individuals were selected as control. Total plasma homocysteine （tHcy） concentration was measured by high-performance liquid chromatography （HPLC）. Lipid profiles were measured for all subjects The polymorphisms of MTHFR gene C677T and MS gene A2756G were analyzed by PCR-RFLP. Results The tHcy concentration in the combined hyperlipidemia patients was significantly higher than that in the control （15.95μmol/L vs 13.43 μmol/L, P〈0.05）. The prevalence of hyperhomocysteinemia （HHcy） in the combined hyperlipidemia group was significantly higher than that in the control （42.2% vs 23.0%, P=0.015）, with the odds ratio （OR） of 3.339 （95%CI： 1.260-8.849）. The hyperlipidemia patients with HHcy had a higher concentration of total cholesterol （TC） than that in the normal tHcy patients （5.67±0.95 mmol/L vs 5.47±0.92 retool/L, P=0.034）. There was no significant difference in genotype or allele frequencies of MTHFR C677T between the hyperlipidemic and control groups. The hyperlipidemia patients with MTHFR CT/TT genotype had a higher concentration of triglyceride （TG） than those with CC genotype （2.24±1.75 mmol/L vs 1.87±0.95 mmol/L, P〈0.05）. Individuals with CT/TT genotype had a higher concentration of tHcy than those with 677CC genotype both in the hyperlipidemia group （12.61±1.24μmol/L vs 11.20±1.37 μmol/L, P〈0.05） and in the control group （14.04±1.48 μmol/L vs 12.61±1.24 μmol/L, P〈0.05）. The percentage of MS 2756 GG/AG genotype in the combined hyperlipidemia group was significantly higher than that in the control （26.7% vs 13.0%, P=0.012）, with the OR of 3.121 （95%C1： 1.288-7.65/）. The hyperlipidemia patients with MS 2756AG/GG genotype had a higher concentration of TC （5.87±0.89 mmol/L vs 5.46±0.93 retool/L, P〈0.05） and LDL-C （3.29±0.81 mmol/L vs 2.94±0.85 retool/L, P〈0.05） than those with AA genotype. However, individuals with 2756AG/GG genotype showed no significant difference in tHcy among those with AA genotype. Conclusion HHcy and MS A2756G mutation may be the risk factors for combined hyperlipidemia. Further study is needed to confirm the role of HHcy and MS A2756G mutation in the development of hyperlipidemia.