Hyperhomocysteinaemia and associated disease

A prospective study to explore the relationship between MTHFR C677T genotype, physiological folate levels, and postpartum psychopathology in at-risk women

BACKGROUND

The etiology of postpartum psychopathologies are not well understood, but folate metabolism pathways are of potential interest. Demands for folate increase dramatically during pregnancy, low folate level has been associated with psychiatric disorders, and supplementation may improve symptomatology. The MTHFR C677T variant influences folate metabolism and has been implicated in depression during pregnancy.

OBJECTIVE

To conduct a prospective longitudinal study to explore the relationship between MTHFR C677T genotype, folate levels, and postpartum psychopathology in at-risk women.

HYPOTHESIS

In the first three months postpartum, folate will moderate a relationship between MTHFR genotype and depression, with TT homozygous women having more symptoms than CC homozygous women.

METHODS

We recruited 365 pregnant women with a history of mood or psychotic disorder, and at 3 postpartum timepoints, administered the Edinburgh Postnatal Depression Scale (EPDS); Clinician-Administered Rating Scale for Mania (CARS-M) and the Positive and Negative Symptom Scale (PANSS) and drew blood for genotype/folate level analysis. We used robust linear regression to investigate interactions between genotype and folate level on the highest EPDS and CARS-M scores, and logistic regression to explore interactions with PANSS psychosis scores above/below cut-off.

RESULTS

There was no significant interaction effect between MTHFR genotype and folate level on highest EPDS (p = 0.36), but there was a significant interaction between genotype, folate level and log(CARS-M) (p = 0.02); post-hoc analyses revealed differences in the effect of folate level between CC/CT, and TT genotypes, with folate level in CC and CT having an inverse relationship with symptoms of mania, while there was no relationship in participants with TT genotype. There was no significant interaction between MTHFR genotype and folate level on the likelihood of meeting positive symptom criteria for psychosis on the PANSS (p = 0.86).

DISCUSSION

These data suggest that perhaps there is a relationship between MTHFR C677T, folate level and some symptoms of postpartum psychopathology.

Distribution of 1298A > C polymorphism of methylenetetrahydrofolate reductase gene in patients with bipolar disorder and schizophrenia

We investigated the genotype frequency of methylenetetrahydrofolate reductase (MTHFR) 1298A > C polymorphism in the group of patients with bipolar disorder type I (BDI) (n = 200) and schizophrenia (n = 200) and in the control group (n = 300). Odds ratio (OR) for patients with BD and schizophrenia in 1298CC homozygous state was 3.768 (95% CI = 1.752–8.104); P = 0.0003; (P = 0.0006 after Bonferroni correction) and 2.694; (95% CI = 1.207–6.013); P = 0.0123 (P = 0.0246 after Bonferroni correction), respectively. The stratification of patients based on gender revealed significant association of 1298CC genotype with female patients only with BDI (OR = 7.293; 95% CI = 2.017–26.363; P = 0.0005).

Our results confirm association of BD and schizophrenia with the 1p36.3 MTHFR locus and with the methyl group transfer using folate-dependent one-carbon pathway.

Transsulfuration Is a Significant Source of Sulfur for Glutathione Production in Human Mammary Epithelial Cells

The transsulfuration pathway, through which homocysteine from the methionine cycle provides sulfur for cystathionine formation, which may subsequently be used for glutathione synthesis, has not heretofore been identified as active in mammary cells. Primary human mammary epithelial cells (HMEC's) were labeled with S35-methionine for 24 hours following pretreatment with a vehicle control, the cysteine biosynthesis inhibitor propargylglycine or the gamma-glutamylcysteine synthesis inhibitor buthionine sulfoximine. Cell lysates were prepared and reacted with glutathione-S-transferase and the fluorescent labeling compound monochlorobimane to form a fluorescent glutathione-bimane conjugate. Comparison of fluorographic and autoradiographic images indicated that glutathione had incorporated S35-methionine demonstrating that functional transsulfuration occurs in mammary cells. Pathway inhibitors reduced incorporation by roughly 80%. Measurement of glutathione production in HMEC's treated with and without hydrogen peroxide and/or pathway inhibitors indicates that the transsulfuration pathway plays a significant role in providing cysteine for glutathione production both normally and under conditions of oxidant stress.

Clinical response to antipsychotic drug treatment: association study of polymorphisms in six candidate genes

Pharmacogenetic studies have demonstrated significant associations between several candidate genes (DRD2, DRD3, 5HTR2A and 5HTR2C, COMT and MTHFR) and antipsychotic drug response. The present study investigates the effect of nine polymorphisms in these genes for an association with antipsychotic treatment response. 329 Caucasian patients with a non-affective psychotic disorder using antipsychotics were included. All patients participated in the longitudinal GROUP-study in The Netherlands. We genotyped 9 SNPs in 6 candidate genes (DRD2: TaqI_A, -141C; DRD3: Ser9Gly; HTR2A: 102-T/C, His452Tyr; HTR2C: Cys23Ser; COMT: Val158Met; MTHFR: 677-C/T) using standard protocols. Polymorphisms were based on previous studies showing associations with positive symptoms treatment response. The Clinical Global Impression - Improvement (CGI-I) scale was used to assess improvement in positive psychotic symptoms since the start of current antipsychotic treatment. Ordinal regression was used for association analyses. Ninety percent of the patients used second generation antipsychotics, with olanzapine (28%) and risperidone (29%) being the most prescribed drugs. Ser9Gly of the dopamine D3 receptor gene (P value 0.034) and 677-C/T of MTHFR (P value 0.019) were tested statistically significant. Gly-carriers and T-carriers, respectively, showed more clinical improvement on the CGI-I. The other polymorphisms did not show a statistically significant association (P values>0.10). In conclusion, we replicated two out of nine of the previously reported associations between polymorphisms and treatment response. The direction and magnitude of the associations presented here in DRD3 (Ser9Gly) and MTHFR (677-C/T) are in line with previous association studies in Caucasian patients. These polymorphisms may be of value for predicting clinical response.

Correlation of methylenetetrahydrofolate reductase polymorphisms with homocysteine metabolism in healthy Lebanese adults

Hyperhomocysteinemia is associated with several vascular and teratogenic conditions. Determinants of total homocysteine concentrations include genetic and nutritional factors. This study assesses the relation between homocysteine concentrations and MTHFR gene polymorphisms at two common alleles (C677T (rs1801133) and A1298C (rs1801131)) as well as other predictors of homocysteine (folate, vitamin B(12), body mass index (BMI), age, and gender) in a group of healthy Lebanese: 109 males and 124 females aged 17-55years. We used serum for the determination of homocysteine, folate and vitamin B(12) levels and blood drawn in EDTA tubes for molecular analysis of MTHFR polymorphisms. Hyperhomocysteinemia was present in 59/233 (25.3%) of the subjects, with male/female ratio of 1.95. Multivariable regression analysis showed that homocysteine levels were negatively related to folate and vitamin B(12) and positively related to male gender and C677T homozygosity; but not A1298C polymorphism, BMI or age. The prevalence of wild, heterozygous, and homozygous C677T genotypes was 45.0%, 43.3% and 11.6%, respectively; with a carrier frequency of 54.9% and allelic frequency of 33.3%. The A1298C genotypic prevalence was 39.5%, 30.9%, and 29.6% respectively; with a carrier frequency of 60.5% and allelic frequency of 45.1%. C677T/A1289C compound heterozygosity was present in 47/233 (20.2%) of volunteers. In this first pilot study, gender, folate, vitamin B(12) and C677T mutational status could explain around 32% of homocysteine variations. Future larger studies are recommended to investigate other predictors of homocysteine variation and combine them with markers explored in this and other studies, in order to evaluate their impact on vascular and/or congenital diseases.

Gene-wide association study between the methylenetetrahydrofolate reductase gene (MTHFR) and schizophrenia in the Japanese population, with an updated meta-analysis on currently available data

Methylenetetrahydrofolate reductase (MTHFR) is a critical molecule for single-carbon transfer reactions. Recent evidence suggests that polymorphisms of MTHFR are related to neural tube deficits and the pathogenesis of schizophrenia. While several studies have demonstrated associations between the gene encoding the MTHFR (MTHFR) polymorphisms and schizophrenia, these studies lack consistency. Therefore, we conducted a gene-wide association study (patients with schizophrenia = 696, control subjects = 747) and performed imputation analysis. Additionally, we performed meta-analysis on currently available data from 18 studies for two common functional polymorphisms (rs1801131 and rs1801133). There were no significant associations with schizophrenia in the single marker analysis for the seven tagging SNPs of MTHFR. In the haplotypic analysis, a nominally significant association was observed between the haplotypes, which included four SNPs (rs1801133, rs17421511, rs17037396, and rs9651118) and the schizophrenic patients. Additionally, the imputation analysis demonstrated there were several associated markers on the MTHFR chromosomal region. However, confirmatory analyses of three tagging SNPs (rs1801133, rs17037396, and rs9651118) and the top SNP (rs17421511) for the imputation results (patients with schizophrenia = 797, control subjects = 1025) failed to replicate the haplotypic analysis and the imputation results. These findings suggest that MTHFR polymorphisms are unlikely to be related to the development of schizophrenia in the Japanese population. However, since our meta-analysis results demonstrated strong support for association of rs1801133 with schizophrenia, further replication studies based on a gene-wide approach need to be considered.

Dietary folate intake, blood folate status, and urinary folate catabolite excretion in Korean women of childbearing age

This study assessed folate intake, folate concentrations in plasma and erythrocytes, plasma total homocysteine (tHcy) concentrations, and urinary excretion of folate metabolites in Korean women of childbearing age. A total of 36 women voluntarily participated in this study. Precise dietary intake for 3 consecutive days was determined by weighing all foods consumed, and folate intake was calculated with a computer-aided dietary analysis system. Folate concentrations in plasma and erythrocytes were determined via microbiological methods and in plasma by HPLC. Urine excreted over the same period of time was collected and assayed for folate catabolites, para-aminobenzoylglutamate (pABG) and para-acetamidobenzoylglutamate (ApABG) by reverse-phase HPLC after affinity chromatography. The mean folate intake was 206.9+/-90.8 microg DFE/d, and the mean concentrations in plasma and erythrocytes were 10.5+/-3.7 and 249.9+/-77.8 ng/mL, respectively. Erythrocyte folate concentration was low in 2.8% of the subjects (<140 ng/mL) and was marginal in 5.5% (140-156 ng/mL). The mean plasma tHcy concentration was 12.7+/-0.2 nmol/mL, and 11% of the subjects evidenced hyperhomocysteinemia (>or=15 nmol/mL). The mean urinary excretion levels of pABG and ApABG were 10.7+/-3.8 and 89.1+/-19.5 nmol/d, respectively. The means of folate reserve and folate turnover rate were 26.2+/-11.6 and 10.5+/-3.9, respectively. We noted positive relationships between folate intake and the folate concentrations in plasma and erythrocytes, as well as the urinary excretions of ApABG and total folate catabolites. In addition, the erythrocytic folate concentrations were positively associated with the urinary excretions of ApABG and total folate catabolites. In conclusion, the folate status of Korean women of childbearing age was marginally deficient with inadequate concentrations of erythrocyte folate and elevated plasma tHcy, largely due to insufficient folate intake. The marginally deficient folate status was confirmed by the low excretion of folate catabolites in urine.

Polymorphic variants of genes encoding MTHFR, MTR, and MTHFD1 and the risk of depression in postmenopausal women in Poland

OBJECTIVE

Disturbances in the folate-dependent one-carbon metabolism have been reported in depression. Polymorphic variants of genes encoding key enzymes of folate and methionine metabolism may have an impact on catecholamine catabolism conducted by catechol-O-methyltransferase.

METHODS

The distribution of polymorphisms of genes encoding methylenetetrahydrofolate reductase (MTHFR); methionine synthase (MTR); 5,10-methylenetetrahydrofolate dehydrogenase, 5,10-methenyltetrahydrofolate cyclohydrolase and 10-formyltetrahydrofolate synthetase (MTHFD1) was examined in postmenopausal women with (n=83) and without depression (n=89).

RESULTS

We found a significant contribution of the MTHFR 677C>T polymorphic variants to depression in postmenopausal women. Odds ratio (OR) for women with depression and MTHFR TT genotype was 3.478 (95% CI=1.377-8.783), P=0.0096 and OR of the TT and CT genotypes was 2.345 (95% CI=1.258-4.373), P=0.0086. Moreover, after stratification based on depression severity in postmenopausal women, we found that the MTHFR TT genotype displayed a 4.831-fold increased risk of moderate and severe depression (95% CI=1.975-11.820, P=0.0008). We did not observe statistical differences in the distribution of MTR 2756A>G and MTHFD1 1958G>A polymorphic variants in groups of postmenopausal women with and without depression. However, the MTR GG genotype exhibited a 5.750-fold increased risk of moderate and severe depression in postmenopausal women (95% CI=1.547-21.379, P=0.013).

CONCLUSIONS

Our findings indicate a significant role of folate and possible methionine metabolism involvement in the development of depression in postmenopausal women.

The effects of maternal protein restriction on the growth of the rat fetus and its amino acid supply

Maternal protein deficiency causes fetal growth retardation which has been associated with the programming of adult disease. The growth of the rat fetus was examined when the mothers were fed on diets containing 180, 90 and 60 g protein/kg. The numbers of fetuses were similar in animals fed on the 180 and 90 g protein/kg diets but the number was significantly reduced in the animals fed on the 60 g protein/kg diet. The fetuses carried by the mothers fed on the 90 g protein/kg diet were 7·5% heavier than those of mothers fed on 180 g protein/kg diet on day 19 of gestation, but by day 21 the situation was reversed and the fetuses in the protein-deficient mothers were 14% smaller. Analysis of the free amino acids in the maternal serum showed that on day 19 the diets containing 90 and 60 g protein/kg led to threonine concentrations that were reduced to 46 and 20% of those found in animals fed on the control (180 g/kg) diet. The other essential amino acids were unchanged, except for a small decrease in the branched-chain amino acids in animals fed on the 60 g protein/kg diet. Both low-protein diets significantly increased the concentrations of glutamic acid+glutamine and glycine in the maternal serum. On day 21 the maternal serum threonine levels were still reduced by about one third in the group fed on the 90 g protein/kg diet. Dietary protein content had no effect on serum threonine concentrations in non-pregnant animals. Analysis of the total free amino acids in the fetuses on day 19 showed that feeding the mother on a low-protein diet did not change amino acid concentrations apart from a decrease in threonine concentrations to 45 and 26% of the control values at 90 and 60 g protein/kg respectively. The results suggest that threonine is of particular importance to the protein-deficient mother and her fetuses. Possible mechanisms for the decrease in free threonine in both mother and fetuses and the consequences of the change in amino acid metabolism are discussed.

Childbearing women of twenty and under are at greater risk than those of twenty-five and over for compromised folate status

This study assessed folate intakes, folate concentrations in plasma and erythrocytes, plasma total homocysteine (tHcy) concentration, and urinary excretion of folate metabolites in Korean women with childbearing potential. A total of 23 women voluntarily participated in this study. Precise dietary intakes for 3 consecutive days were determined by weighing all foods consumed and folate intake was calculated using a computer-aided dietary analysis system. Folate concentration of plasma and erythrocytes was determined by a microbiological method. Plasma tHcy concentration was assayed using an HPLC analysis method. Urine excreted over the same period of time was collected and folate catabolites, para-aminobenzoylglutamate (pABG) and para-acetamidobenzoylglutamate (ApABG), were evaluated using a reverse-phase HPLC method after affinity chromatography. Young women of 20 and under were likely to consume less folate with low energy intake, had lower folate concentration in plasma and erythrocytes, and excreted a lesser amount of ApABG and total folate catabolites than women of 25 years and over. The results of this study confirmed that young Korean women with childbearing potential, especially those under 21 years of age, might be at risk for compromised folate status due to insufficient folate intakes from inadequate energy consumption.

Association of 677C>T polymorphism of methylenetetrahydrofolate reductase (MTHFR) gene with bipolar disorder and schizophrenia

Methylenetetrahydrofolate reductase (MTHFR) gene polymorphism 677C>T has been shown to be a risk factor for psychiatric disorders. We investigated the genotype and allelic frequencies of MTHFR 677C>T polymorphism in the group of patients with bipolar disorder type I (BDI) (n=200) and schizophrenia (n=200), and in the control group (n=300). Odds ratio (OR) for patients with BD and schizophrenia with 677T allele was 1.988 ((95% CI=1.370-2.883); P=0.0003 (P=0.0006 after Bonferroni correction)) and 1.796 ((95% CI=1.237-2.609); P=0.0020 (P=0.0040 after Bonferroni correction)), respectively. The stratification of patients based on gender revealed significant association of 677T allele with male patients with BDI and schizophrenia (OR=2.393; 95% CI=1.429-4.006; P=0.0008 and OR=2.036; 95% CI=1.207-3.433; P=0.0073, respectively). This finding indicates possible association of BD and schizophrenia with the 1p36.3 MTHFR locus.

Gene--nutrition interactions in coronary artery disease: correlation between the MTHFR C677T polymorphism and folate and homocysteine status in a Korean population

INTRODUCTION

Elevated plasma total homocysteine is a major risk for coronary artery disease (CAD). Methyltetrahydrofolate reductase (MTHFR) is a main regulatory enzyme in homocysteine metabolism; a common C677T mutation in the MTHFR gene results in decreased enzyme activity, and contributes to increased homocysteine levels and decreased folate levels. We investigated the frequency of MTHFR C677T alleles in a Korean population, determined the genotype-specific threshold levels of folate or vitamin B12, and investigated the relationship between the TT genotype and the risk of CAD.

MATERIALS AND METHODS

We enrolled a study population of 163 CAD patients and 50 control subjects, and screened the MTHFR C677T polymorphism using real-time PCR with melting point analysis. Levels of plasma homocysteine, folate and vitamin B12 were also determined. We then defined the genotype-specific threshold values of folate and vitamin B12 required to keep homocysteine levels in a normal range for individuals of each MTHFR C677T genotype.

RESULTS

The frequency of the TT genotype was 18% in control subjects and 26% in patients group (P>0.05). Individuals homozygous for the TT genotype had significantly elevated homocysteine levels (P<0.05). The genotype-specific folate threshold level was significantly higher in TT individuals than in the CC or CT genotypes. The OR of individuals with low folate status and the TT genotype to estimate the relative risk of CAD was 2.2 and the OR of those with high folate status and the TT genotype was 1.5 (95% CI, 0.5-9.6 and 0.7-3.2, respectively).

CONCLUSION

We were able to define a gene-nutrient interaction that shows a higher risk for CAD based on specific threshold folate levels required by different MTHFR C677T genotypes in a Korean population.

Serum homocysteine levels after preterm premature rupture of the membranes

OBJECTIVE

Preterm premature rupture of the membranes (PPROM) is believed to be caused, in part, by abnormalities of collagen and increased levels of oxidative stress. Elevated homocysteine levels have been shown to induce these same pathophysiologic changes. We tested the hypothesis that serum homocysteine levels would be higher in women with PPROM when compared with matched control women.

STUDY DESIGN

A secondary analysis derived from 2 previously completed studies performed in the National Institutes of Child Health and Human Development Maternal-Fetal Medicine Units (MFMU) Network. We identified 99 study cases with PPROM (24 to 32 weeks' gestation) and matched them with 99 asymptomatic control women from an observational study of preterm birth prediction. Cases and control women were matched for race, gestational age at sampling, and MFMU Network center. Serum homocysteine levels were determined by immunoassay in batch fashion by personnel masked to study arm and clinical outcomes. Serum homocysteine levels were compared between groups, as were the baseline characteristics of maternal age, cigarette smoking, nulliparity, infections during pregnancy, and body mass index (BMI) <19.8 kg/m 2. Serum homocysteine levels were dichotomized as >75th, 90th, and 95th %ile of control women, and the likelihood of elevated homocysteine levels was determined in women who smoked, had a BMI <19.8 kg/m 2, or who had PPROM. Statistical analyses included the Wilcoxon rank sum, chi-square, and Pearson correlation coefficient, where appropriate. Baseline characteristics were controlled with a logistic regression model.

RESULTS

Serum homocysteine levels measured in patients with PPROM were not significantly different from matched control women: median and (25th to 75th %ile): 4.9 (3.5-6.2) vs 4.8 (3.9-6.2 micromol/L), P =.73. In our population, neither the number of cigarettes smoked ( r = -0.08, P =.57), nor BMI ( r = -0.08, P =.24) correlated with serum homocysteine levels. The strongest association was seen in women with PPROM having serum homocysteine levels >95th %ile of control women (odds ratio [OR] 2.7, P =.10). After adjusting for baseline characteristics, no correlation between serum homocysteine level and the presence of PPROM was seen, OR 1.0 (.9-1.1); P =.99.

CONCLUSION

Women presenting with PPROM did not have significantly increased serum homocysteine levels when compared with control women.

Plasma homocysteine and retinal artery occlusive disease: a case-control study

BACKGROUND

Previous studies have documented that elevated plasma homocysteine is a risk factor for cardiovascular, cerebrovascular and peripheral vascular disease. In a case-control study, we sought to determine whether elevated homocysteine (HCY) is a risk factor for retinal artery occlusive disease PATIENTS AND METHODS. Study subjects consisted of 20 patients (12 male, 8 female) (mean age, 55.8; range 42-70 years) with clinical and objective evidence of retinal vascular occlusive disease and 20 age-matched control subjects (9 males, 11 females) (mean age, 55.3 years; range 50-68 years). Hyperhomocysteinemia was defined as a plasma HCY level >15 micromol/L by HPLC. We also measured concentrations of triglycerides, and total cholesterol, LDL cholesterol, and HDL cholesterol.

RESULTS

The mean plasma HCY level in the patient group was 21.23+/-9.53 micromol/L (range, 8.00-43.99 micromol/L) compared with 12.59+/-4.97 micromol/L (range, 6.38 to 22.88 micromol/L) in the control group (P<0.008). There was no correlation between HCY and serum triglycerides or cholesterol levels within each group. We conclude that high plasma HCY level may be a risk factor for retinal artery occlusive disease.

The effect of folic acid, vitamin B6 and vitamin B12 on the homocysteine levels in rabbits fed by methionine-enriched diets

Atherosclerosis is an important cause of cardiovascular morbidity and mortality in recent years. Hyperhomocysteinemia is recognized as an independent risk factor for premature atherosclerosis and venous thrombosis. It is suggested that administration of folic acid, vitamin B6 and vitamin B12 may decrease homocysteine levels. In our study, we induced hyperhomocysteinemia in rabbits by giving methionine and studied the effects of folic acid, vitamin B6 and vitamin B12 on homocysteine levels. A total of 40 (20 female, 20 male New Zealand rabbits) were divided into four groups, each consisting of 10 rabbits. Methionine (100 mg/kg/day), methionine (100 mg/kg/day) plus vitamin B6 (30 mg/kg/day), methionine (100 mg/kg/day) plus vitamin B12 (80 mg/kg/day) and methionine (100 mg/kg/day) plus folic acid (20 mg/kg/day) were given to the first, second, third and forth groups respectively. These rabbits were followed up for two months. We studied homocysteine levels on the 0, 20th, 40th and 60th days in all groups. In rabbits we induced hyperhomocysteinemia by giving methionine for 2 months. The decreases of homocysteine levels in the forth group were significant with respect to the second and third groups. Folic acid supplementation clearly resulted in a reduction of plasma homocysteine levels, whereas vitamin B12 was little effective and vitamin B6 failed to show an effect. We conclude that even folic acid treatment alone may be sufficient for decreasing negative effects of homocysteine.

Maternal plasma homocysteine levels in women with preterm premature rupture of membranes

Homocysteine is a sulfur-containing amino acid produced by the breakdown of methionine. Plasma homocysteine levels can be elevated due to a variety of genetic and nutritional factors. Poor nutrition from diets low in folate and vitamin B12 can lead to hyperhomocysteinemia. Mildly elevated levels of homocysteine have been implicated in a number of disease processes such as atherosclerotic vascular disease and adverse obstetrical outcomes. High levels of plasma homocysteine are also associated with abnormal collagen cross-linking. Due to homocysteine's effects on connective tissue integrity, it is hypothesized that hyperhomocysteinemia in pregnancy is associated with preterm premature rupture of membranes (PPROM). Hyperhomocysteinemia, therefore, could be a treatable cause of this important public health concern.

Folic acid: influence on the outcome of pregnancy

The periconceptional use of folic acid-containing supplements reduces the first occurrence, as well as the recurrence, of neural tube defects. Women of populations in which adverse pregnancy outcomes are prevalent often consume diets that contain a low density of vitamins and minerals, including folate. Folate intake may need to be sustained after complete closure of the neural tube to decrease the risk of other poor pregnancy outcomes. A central feature of embryonic and fetal development is widespread cell division; folate is central because of its role in nucleic acid synthesis. During gestation, marginal folate nutriture can impair cellular growth and replication in the fetus or placenta. Folate deficiency can occur because dietary folate intake is low or because the metabolic requirement for folate is increased by a particular genetic defect or defects. During pregnancy, low concentrations of dietary and circulating folate are associated with increased risks of preterm delivery, infant low birth weight, and fetal growth retardation. A metabolic effect of folate deficiency is an elevation of blood homocysteine. Likewise, the presence of maternal homocysteine concentrations have been associated both with increased habitual spontaneous abortion and pregnancy complications (eg, placental abruption and preeclampsia), which increase the risk of poor pregnancy outcome and of decreased birth weight and gestation duration.

Association between the methylenetetrahydrofolate reductase 677C-->T missense mutation and schizophrenia

The schizophrenia phenotype is heterogeneous with respect to clinical presentation, long-term response to medication, and outcome, possibly reflecting genetic heterogeneity and/or the presence of modifier genes. Compared to non-responders, schizophrenic patients who are responders to neuroleptic medications are characterized by a high female/male ratio, a better long-term outcome and more frequently disturbed dopamine neurotransmission. In this study, we compared two groups of schizophrenic patients selected on the basis of their long-term response to neuroleptics (excellent responders and non-responders) and a group of healthy volunteers, with regard to a missense mutation (677C-->T) in the methylenetetrahydrofolate reductase (MTHFR) gene. This polymorphism was chosen because it is functional and was previously associated with schizophrenia. The present study revealed a significant association between schizophrenia and allele T of this gene. This association was entirely due to an over-representation of allele T in responder patients compared to controls; nonresponder patients did not differ from controls. Genotype TT was more frequent in responder patients compared to controls, thus replicating the findings of Arinami et al. These results strongly suggest that the MTHFR gene is involved in the pathogenesis of schizophrenia characterized by a rapid and sustained therapeutic response to typical neuroleptics and/or a good long-term prognosis/favorable therapeutic outcome.

A common mutation A1298C in human methylenetetrahydrofolate reductase gene: association with plasma total homocysteine and folate concentrations

Methylenetetrahydrofolate reductase (MTHFR) is one of the main regulatory enzymes of homocysteine metabolism. Previous studies revealed that a common mutation in MTHFR gene C677T is related to hyperhomocysteinemia and occlusive vascular pathology. In the current study, we determined the prevalence of a newly described mutation in the human MTHFR gene A1298C, and the already known C677T mutation, and related them to plasma total homocysteine and folate concentrations. We studied 377 Jewish subjects, including 190 men and 186 women aged 56.8 +/- 13 y (range 32-95 y). The frequency of the homozygotes for the A1298C and the C677T MTHFR mutations was common in the Jewish Israeli population (0.34 and 0.37, respectively). Subjects homozygous (TT) for the C677T mutation had significantly greater plasma total homocysteine concentrations (P < 0.01) than subjects without the mutation (CC). Homozygotes (CC) for the A1298C mutation did not have elevated plasma total homocysteine concentrations. Our study indicated that subjects with the 677CC/1298CC genotype had significantly lower concentrations (P < 0. 05) than those with a 677CC/1298AA genotype. Neither mutation (the A1298C and the C677T) was associated with established cardiovascular risk factors such as hypertension, elevated total cholesterol or body mass index.

Plasma total homocysteine response to oral doses of folic acid and pyridoxine hydrochloride (vitamin B6) in healthy individuals. Oral doses of vitamin B6 reduce concentrations of serum folate

Plasma total homocysteine response was compared in four groups of healthy individuals given orally divided doses of vitamin supplementations for a duration of 5 weeks. The vitamin supplements; A, 0.3 mg folic acid; B, 120 mg vitamin B6; C, combination of 0.3 mg folic acid and 120 mg vitamin B6 or D, 0.6 mg folic acid reduced the concentrations of plasma total homocysteine 20, 17, 32 and 24%, respectively. However, the intergroup comparisons did not show a significant difference in the effects of vitamin supplements. Multivariate analysis with correction for differences in pre-supplement values indicated a significant effect of vitamin B6 supplementation on plasma total homocysteine and serum folate. Our data show that plasma total homocysteine concentrations are reduced with low to medium divided doses of folic acid alone or in combination with vitamin B6.