Homocysteine,MTHFR gene polymorphisms, and cardio-cerebrovascular risk

Methylenetetrahydrofolate reductase C677T mutation in patients with alopecia areata in Turkish population

OBJECTIVE

Methylene-tetrahydrofolate reductase (MTHFR) is a key enzyme regulating folate metabolism and it is thought to influence DNA methylation and nucleic acid synthesis. Mutations in the MTHFR gene have been associated with several autoimmune disorders in previous studies. Alopecia areata (AA) is considered to be a tissue-specific autoimmune disease as the hair follicle has been targeted and antibodies to their own hair follicle structures have been developed. Since there is a common shared pathway between AA and other autoimmune disorders, we aimed to investigate a possible association between the MTHFR gene C677T mutation and AA susceptibility in the Turkish population.

METHODS

The study included 136 patients affected by AA and 130 healthy controls. Genomic DNA was isolated and genotyped using a polymerase chain reaction (PCR)-based restriction fragment length polymorphism (RFLP) assay for the MTHFR gene C677T mutation.

RESULTS

The distributions of genotype and allele frequencies of MTHFR gene C677T mutation were statistically different between AA patients and the control group (p=0.036 and p=0.011, respectively). High differences were also observed when the patients and controls were compared according to CC versus CT+TT (p=0.012). CT+TT genotypes and T allele of MTHFR gene C677T mutation were found to be a susceptibility factor for AA in the Turkish population.

CONCLUSION

The results suggest that MTHFR gene C677T mutation may have an effect on the risk of alopecia areata in the Turkish population. This is the first study reporting the association between the MTHFR (C677T) genotype and AA.

Genes and primary headaches: discovering new potential therapeutic targets

Genetic studies have clearly shown that primary headaches (migraine, tension-type headache and cluster headache) are multifactorial disorders characterized by a complex interaction between different genes and environmental factors. Genetic association studies have highlighted a potential role in the etiopathogenesis of these disorders for several genes related to vascular, neuronal and neuroendocrine functions. A potential role as a therapeutic target is now emerging for some of these genes. The main purpose of this review is to describe new advances in our knowledge regarding the role of MTHFR, KCNK18, TRPV1, TRPV3 and HCRTR genes in primary headache disorders. Involvement of these genes in primary headaches, as well as their potential role in the therapy of these disorders, will be discussed.

Methylenetetrahydrofolate Reductase C677T and A1298C Mutations in Women with Recurrent Spontaneous Abortions in the Northwest of Iran

Introduction. Recurrent spontaneous abortion (RSA) is a significant obstetrical complication that may occur during pregnancy. Various studies in recent years have indicated that two common mutations (C677T and A1298C) of the methylenetetrahydrofolate reductase (MTHFR) gene are risk factor for RSA. This study was carried out to determine the influence of (C677T and A1298C) of the methylenetetrahydrofolate reductase (MTHFR) gene mutations with RSA. Materials and Methods. A total of 139 women were included in this study: 89 women with two or more consecutive miscarriages and 50 healthy controls. Total genomic DNA was isolated from blood leukocytes. To determine the frequency of the two common C677T and A1298C MTHFR gene mutations in the patients and controls, we used two methods, amplification refractory mutation system-PCR and PCR-restriction fragment length polymorphism. Results. There is no significant difference in the prevalence of 677T/T genotype among women with RSA and healthy controls (P = 0.285). Also no statistically significant difference in the frequency of A1298C MTHFR gene mutation was detected between the two groups (P = 0.175 ). Conclusion. In conclusion, the results indicate that the Amplification Refractory Mutation System-PCR method was in complete concordance with the results obtained by standard PCR-restriction fragment length polymorphism method. The results also show no significant difference in MTHFR C677T/A1298C genotype distribution among the two groups; therefore, further studies on larger population and other genetic variants to better understand the pathobiology of RSA are needed.

The role of homocysteine and methylenetetrahydrofolate reductase, methionine synthase, methionine synthase reductase polymorphisms in the development of cardiovascular diseases and hypertension

Cardiovascular diseases (CVDs) are the leading causes of death in the developed countries. Elevated homocysteine level is as an independent risk factor of CVDs. The C677T and A1298C variants of methylenetetrahydrofolate reductase gene (MTHFR) have been shown to influence folate and homocysteine metabolisms. However, the relationship between MTHFR polymorphisms and hyperhomocysteinemia has not been well established yet. The gene variants were also reported to be associated with CVDs. In addition, the C677T polymorphisms may play a role in the development of hypertension. Recent research evidence has suggested that MTHFR variants might be independently linked to CVDs and hypertension, because of the involvement of the MTHFR enzyme product (5-methyl-tetrahydrofolate /5-MTHF) in the regulation of endothelial functions. Further research is required to investigate the association between gene polymorphisms of folate-metabolizing enzymes and CVDs, and to identify the possible role of the relevant gene variants in the molecular pathogenesis of hyperhomocysteinemia. Orv. Hetil., 2012, 153, 445–453.

Retrospective approach to methylenetetrahydrofolate reductase mutations in children

Methylenetetrahydrofolate reductase reduces methyltetrahydrofolate, a cosubstrate in the remethylation of homocysteine, from methylenetetrahydrofolate. Congenital defects, hematologic tumors, and intrauterine growth retardation can occur during childhood. This study evaluated clinical and laboratory treatment approaches in children diagnosed with methylenetetrahydrofolate reductase mutations. Our group included 23 boys and 14 girls, aged 103.4 ± 70.8 months S.D. Clinical findings of patients and homocysteine, vitamin B12, folate, hemogram, electroencephalography, cranial magnetic resonance imaging, and echocardiography data were evaluated in terms of treatment approach. Our patients' findings included vitamin B12 at 400.4 ± 224.6 pg/mL S.D. (normal range, 300-700 pg/mL), folate at 10.1 ± 4.5 ng/mL S.D. (normal range, 1.8-9 ng/mL), and homocysteine at 8.4 ± 4.7 μmol/L S.D. (normal range, 5.5-17 μmol/L). Eighty-eight percent of patients demonstrated clinical findings. In comparisons involving categorical variables between groups, χ(2) tests were used. No relationship was evident between mutation type, laboratory data, and clinical severity. All mothers who had MTHFR mutations and had babies with sacral dimples had taken folate supplements during pregnancy. To avoid the risk of neural tube defects, pregnant women with a MTHFR mutation may require higher than normally recommended doses of folic acid supplementation for optimum health.

Homocysteine enriched diet leads to prolonged QT interval and reduced left ventricular performance in telemetric monitored mice

BACKGROUND AND AIMS

Homocysteine (Hcy) is a sulfur-containing, non-protein amino acid produced in the metabolic pathway of methionine. Hyperhomocysteinemia is associated with cerebro- and cardiovascular disease in industrialized countries, mostly resulting from protein rich diet and sedentary life style. Matrix metalloproteinases are involved in cardiac remodeling, leading to degradation of intercellular junctions, cardiac connexins and basement membranes. The study was designed to investigate the relationship between Hcy, cardiac remodeling, cardiac performance, and rhythm disturbances in an animal model of hyperhomocysteinemia. We tested the hypothesis that induction of matrix metalloproteinase-2 and matrix metalloproteinase-9 leads to connexin 40, connexin 43, connexin 45 expression changes contributing to decreased cardiac performance and disturbed atrioventricular conduction.

METHODS AND RESULTS

Hcy was added to drinking water of male C57/BL6J mice to achieve moderate Hcy blood levels. ECG was monitored in conscious mice with a telemetric ECG device; echocardiography was used for assessment of left ventricular function. Immunoblotting was used to evaluate matrix metalloproteinase-2, matrix metalloproteinase-9, connexin 40, connexin 43, and connexin 45 expression in cardiac tissue. Animals fed Hcy showed significant prolongation of QRS, QTc, and PR intervals along with reduced left ventricular function. Western blotting showed increased expression of matrix metalloproteinase-2, matrix metalloproteinase-9 and decreased expression of connexin 40, 43, and 45.

CONCLUSION

Hcy has been identified as a nutritional factor contributing to cardiovascular disease. Cardiac remodeling induced by matrix metalloproteinase-2 and matrix metalloproteinase-9 and decreased expression of connexin 40, 43, and 45 appears to play a role in the pathomechanism of atrioventricular conduction delay and ventricular dilatation in hyperhomocysteinemia.

Endothelial microparticle formation in moderate concentrations of homocysteine and methionine in vitro

Microparticles (MPs) are small membrane vesicles released by stimulated or apoptotic cells, including the endothelium. Hyperhomocysteinemia (HHcy) is a blood disorder characterized by an increase in the plasma concentrations of total homocysteine (Hcy). The plasma Hcy level is determined by environmental factors (dietary habits, i.e. the intake of folic acid, FA) and genetic factors (N (5),N (10)-methylenetetrahydro-folate reductase, MTHFR, polymorphism 677C>T). To evaluate whether moderate Hcy concentrations induce endothelial MP formation, the role of FA supplementation and the influence of MTHFR polymorphism were analysed. Human umbilical vein endothelial cells (HUVEC) were treated in vitro with 50 μM of Hcy and methionine (Met). The MP number and apoptotic phenotype were analyzed using flow cytometry. Increasing doses of FA (5, 15 and 50 μM) were used to reduce the HHcy effect. The MTHFR 677C>T polymorphism was determined. HUVEC stimulated by Hcy produced significantly more MPs than HUVEC under the control conditions: 3,551 ± 620 vs 2,270 ± 657 kMP (p = 0.02). Supplementation with FA at concentrations of 5, 15 and 50 μM reduced the MP count in the cell culture supernatant to 345 ± 332, 873 ± 329, and 688 ± 453 kMP, respectively (p = 0.03). MTHFR 677C>T heterozygosity was associated with a significant increase in MP formation after stimulation with Hcy compared to the control conditions: 3,617 ± 152 vs 1,518 ± 343 kMP (p = 0.02). Furthermore, the MTHFR genotype altered MP formation after Met loading. On average, 24% of the entire MP population was apoptotic (annexin V-positive). Endothelial function impairment due to HHcy is related to MP shedding, which may involve platelets and other blood and vascular cells. MP shedding is a physiological response to moderate HHcy.

MTHFR genotype and differential evolution of metabolic parameters after initiation of a second generation antipsychotic: an observational study

Most second-generation antipsychotics (SGAs) induce metabolic disturbances, but large differences exist in the degree to which individual patients develop these. Little is known about genetic factors associated with differential liability. Cross-sectional studies suggested an association between polymorphisms in 5,10-methylenetetraydrofolate reductase (MTHFR) and metabolic syndrome in patients with schizophrenia. This study aimed to assess whether the C677T (rs1801133) or A1298C (rs1801131) polymorphism in the MTHFR gene predict differential evolution of metabolic parameters over the course of a 3-month follow-up period after initiation of an SGA. One hundred and four patients with schizophrenia initiated on a SGA were measured at baseline, 6 weeks and 3 months. MTHFR A1298C, but not C677T, genotype predicted pos-baseline increases in weight [beta=2.5, standard error (SE)=0.92, P=0.006], waist circumference (beta=2.0, SE=1.0, P=0.050), fasting glucose (beta=2.8, SE=1.2, P=0.024) and glucose at 120 min during the Oral Glucose Tolerance Test (beta=10.7, SE=4.5, P=0.018) following a de novo metabolic challenge with a specific SGA. A1298C allele carriers consistently displayed the most unfavorable evolution of metabolic parameters. Thus, MTHFR A1298C genotype may explain part of the individual liability to metabolic disturbances in patients with schizophrenia.

Hyperhomocysteinemia Prevalence Among Patients With Venous Thromboembolism

The aim of this study is to evaluate the plasma total homocysteine level in patients with venous thromboembolism (VTE) and to investigate the effect of different risk factors on plasma levels. Ninety-three-patients with VTE and 37-control participants diagnosed with other than VTE were included in the study. Plasma homocysteine levels and the factors affecting plasma homocysteine levels were evaluated. Plasma homocysteine level was higher among patients with VTE compared to the controls independent from vitamin B12 and folate levels. The prevalence of hyperhomocysteinemia in VTE was 63%. Plasma homocysteine level was higher in patients with PE than deep venous thrombosis (DVT; 23 ± 13.7 vs 16 ± 5.8 μmol/L, P = .018). With regression analysis hyperhomocysteinemia was found to be associated with a 4.8-fold increased risk of VTE. Hyperhomocysteinemia is a common and possibly modifiable risk factor that should be considered when screening patients with VTE. Secondary causes of hyperhomocysteinemia especially vitamin B12 deficiency should be monitored in patients with VTE to prevent recurrences.

Effect of enalapril on plasma homocysteine levels in patients with essential hypertension

OBJECTIVE

To investigate the effect of enalapril on plasma homocysteine (Hcy) levels and the association of methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism with the changes of Hcy levels in response to enalapril among patients with essential hypertension.

METHODS

A total of 130 patients with mild-to-moderate essential hypertension were enrolled and enalapril was orally administered at a dose of 10 mg/d for eight weeks. Plasma Hcy levels were measured by denaturing high-performance liquid chromatography (DHPLC) at baseline and after eight weeks of treatment. Genotyping of MTHFR C677T polymorphism was performed by TaqMan probe technique.

RESULTS

Compared with baseline, plasma Hcy levels did not change significantly after eight weeks (P=0.81). Stratified by baseline Hcy levels, a significant increase in plasma Hcy levels (P=0.02) among those with Hcy <10 micromol/L was observed, in contrast to no significant changes in plasma Hcy levels (P=0.54) among those with Hcy > or =10 micromol/L. No significant association was observed between MTHFR C677T polymorphism and changes in Hcy levels in response to enalapril.

CONCLUSIONS

Enalapril may cause an increase in plasma Hcy levels among the hypertensives with low baseline Hcy levels. There was no significant association between MTHFR C677T genotypes and changes in Hcy levels in response to enalapril among subjects with essential hypertension.

[Determinants and relationship of homocysteinemia with cardiometabolic risk factors. A study in Benin, West Africa]

INTRODUCTION

Elevated circulating homocysteine (Hcy) is considered as an independent cardiovascular disease risk factor. Hyperhomocysteinaemia (HHcy) is influenced by nutritional, genetic, and environmental factors. The purpose of the study was to assess HHcy prevalence in Benin, its association with intakes of B-vitamins (B2, B6, B9, B12), alcohol intake, and socio-economic status (SES), and its links with other factors of cardio-metabolic risk.

METHODS

The cross-sectional study included 541 apparently healthy subjects, aged 25 to 65 years, from three sites: the main city, a small city and a rural area. Hcy was measured with an ELISA test kit. The HHcy cut-off was 12 μmol/L. Dietary intake was assessed with three 24-hour recalls. We used a structured questionnaire to assess alcohol consumption, demographics, and SES according to education and an amenity score as income proxy. Criteria for obesity, hypertension, dyslipidemia and hyperglycemia were primarily those of World Health Organization (WHO) and the International Diabetes Federation.

RESULTS

Mean age was 38.1 ± 10.1 years. The prevalence of HHcy was 52.2% in men and 24.7% in women. In multiple linear regression models, Hcy in men was positively associated with alcohol intake, but only alcohol in beer. In women, Hcy was negatively related to vitamin B12 intake. According to multivariate models of cardio-metabolic risk factors, HHcy was associated in women with more than twice the odds of hypertension and with high TC/HDL-c ratio. In men, Hcy was positively and independently associated with diastolic blood pressure and with LDL-cholesterol and total cholesterol in linear regression models.

DISCUSSION

The prevalence of HHcy is high in Benin, when compared with other studies, and it was as expected higher in men than in women. Elevated Hcy was associated with inadequate intake of vitamin B12 in women, whereas alcohol consumption and its negative correlation with B12 intake was also involved in men. Although HHcy was independently associated with hypertension (in women) and more adverse cholesterol profile, no inference can be made because of the cross-sectional design of the study.

Lack of carotid stiffening associated with MTHFR 677TT genotype in cardiorespiratory fit adults

The TT genotype of C677T polymorphism in 5,10-methylenetetrahydrofolate reductase (MTHFR) induces elevation of homocysteine level and leads to atherosclerosis and arterial stiffening. Furthermore, cardiorespiratory fitness level is also associated with arterial stiffness. In the present study, a cross-sectional investigation of 763 Japanese men and women (18-70 yr old) was performed to clarify the effects of cardiorespiratory fitness on the relationship between arterial stiffness and MTHFR C677T gene polymorphism. Arterial stiffness was assessed by carotid beta-stiffness with ultrasonography and tonometry. The study subjects were divided into high-cardiorespiratory fitness (High-Fit) and low-cardiorespiratory fitness (Low-Fit) groups based on the median value of peak oxygen uptake in each sex and decade. The plasma homocysteine level was higher in the TT genotype of MTHFR C677T polymorphism compared with CC and CT genotype individuals. MTHFR C677T polymorphism showed no effect on carotid beta-stiffness, but there was a significant interaction effect between fitness and MTHFR C677T polymorphism on carotid beta-stiffness (P = 0.0017). In the Low-Fit subjects, carotid beta-stiffness was significantly higher in individuals with the TT genotype than the CC and CT genotypes. However, there were no such differences in High-Fit subjects. In addition, beta-stiffness and plasma homocysteine levels were positively correlated in Low-Fit subjects with the TT genotype (r = 0.71, P < 0.0001), but no such correlations were observed in High-Fit subjects. In CC and CT genotype individuals, there were also no such correlations in either fitness level. These results suggest that the higher cardiorespiratory fitness may attenuate central artery stiffening associated with MTHFR C677T polymorphism.

Polymorphism of genes encoding homocysteine metabolism-related enzymes and risk for cardiovascular disease

The aim of this review is to present a general overview of the relationships among homocysteine metabolism, polymorphism of the genes encoding homocysteine metabolism-related enzymes, and the nutrients influencing the plasma homocysteine level. Combining these factors creates a profile of an individual's susceptibility to complex diseases associated with hyperhomocysteinemia. Homocysteine is an amino acid derived from the demethylation of methionine. Hyperhomocysteinemia is associated with an increased risk of several complex diseases, including cardiovascular diseases. The level of plasma homocysteine depends on the combined effects of genetic and environmental factors. Polymorphisms of genes encoding homocysteine metabolism-related enzymes, such as methylenetetrahydrofolate reductase, methionine synthase, methionine synthase reductase, and cystathionine beta-synthase, influence plasma homocysteine concentration and thereby cardiovascular health. On the other hand, homocysteine metabolism may be modulated by dietary intake of the nutrients involved in homocysteine metabolism (ie, folates, vitamin B(6), and vitamin B(12)). Thus, the appropriate health-promoting doses of these nutrients may vary among certain groups of individuals, depending on their genotypes and other risk factors for complex diseases. Better understanding of the relationship between genotype and nutrition influencing the plasma total homocysteine level and cardiovascular health may improve the cardiovascular diagnostic tests (ie, measurement of biologic markers). It could be possible to define the level of progression, severity, and susceptibility to disease much earlier than it is done now. In conclusion, the introduction of combined dietary and pharmacologic treatment would be possible at the initial stages of disease.

Fetal placental thrombosis and neonatal implications

We present the neonatal complications of two premature newborn infants whose placentas demonstrated placental thrombosis in the fetal circulation. Both mothers presented with a 3-day history of decreased fetal movements before delivery. The first infant presented with thrombocytopenia and disseminated intravascular coagulation. The second infant had extended bilateral extended hemorrhagic venous infarctions. Severe fetal placental vascular lesions seem to be a predisposing factor for some adverse neonatal outcomes. We present these two cases with a brief review of the literature.

Hyperhomocysteinemia in uremia--a red flag in a disrupted circuit

Hyperhomocysteinemia is an independent cardiovascular risk factor, according to most observational studies and to studies using the Mendelian randomization approach, utilizing the common polymorphism C677T of methylene tetrahydrofolate reductase. In contrast, the most recent secondary preventive intervention studies, in the general population and in chronic kidney disease (CKD) and uremia, which are all negative (with the possible notable exception of stroke), point to other directions. However, all trials use folic acid in various dosages as a means to reduce homocysteine levels, with the addition of vitamins B6 and B12. It is possible that folic acid has negative effects, which offset the benefits; alternatively, homocysteine could be an innocent by-stander, or a surrogate of the real culprit. The latter possibility leads us to the search for potential candidates. First, the accumulation of homocysteine in blood leads to an intracellular increase of S-adenosylhomocysteine (AdoHcy), a powerful competitive methyltransferase inhibitor, which by itself is considered a predictor of cardiovascular events. DNA methyltransferases are among the principal targets of hyperhomocysteinemia, as studies in several cell culture and animal models, as well as in humans, show. In CKD and in uremia, hyperhomocysteinemia and high intracellular AdoHcy are present and are associated with abnormal allelic expression of genes regulated through methylation, such as imprinted genes, and pseudoautosomal genes, thus pointing to epigenetic dysregulation. These alterations are susceptible to reversal upon homocysteine-lowering therapy obtained through folate administration. Second, it has to be kept in mind that homocysteine is mainly protein-bound, and its effects could be linked therefore to protein homocysteinylation. In this respect, increased protein homocysteinylation has been found in uremia, leading to alterations in protein function.

Gene polymorphisms in association with emerging cardiovascular risk markers in adult women

Background

Evidence on the associations of emerging cardiovascular disease risk factors/markers with genes may help identify intermediate pathways of disease susceptibility in the general population. This population-based study is aimed to determine the presence of associations between a wide array of genetic variants and emerging cardiovascular risk markers among adult US women.

Methods

The current analysis was performed among the National Health and Nutrition Examination Survey (NHANES) III phase 2 samples of adult women aged 17 years and older (sample size n = 3409). Fourteen candidate genes within ADRB2, ADRB3, CAT, CRP, F2, F5, FGB, ITGB3, MTHFR, NOS3, PON1, PPARG, TLR4, and TNF were examined for associations with emerging cardiovascular risk markers such as serum C-reactive protein, homocysteine, uric acid, and plasma fibrinogen. Linear regression models were performed using SAS-callable SUDAAN 9.0. The covariates included age, race/ethnicity, education, menopausal status, female hormone use, aspirin use, and lifestyle factors.

Results

In covariate-adjusted models, serum C-reactive protein concentrations were significantly (P value controlling for false-discovery rate ≤ 0.05) associated with polymorphisms in CRP (rs3093058, rs1205), MTHFR (rs1801131), and ADRB3 (rs4994). Serum homocysteine levels were significantly associated with MTHFR (rs1801133).

Conclusion

The significant associations between certain gene variants with concentration variations in serum C-reactive protein and homocysteine among adult women need to be confirmed in further genetic association studies.

Genetics of homocysteine metabolism and associated disorders

Homocysteine is a sulfur-containing amino acid derived from the metabolism of methionine, an essential amino acid, and is metabolized by one of two pathways: remethylation or transsulfuration. Abnormalities of these pathways lead to hyperhomocysteinemia. Hyperhomocysteinemia is observed in approximately 5% of the general population and is associated with an increased risk for many disorders, including vascular and neurodegenerative diseases, autoimmune disorders, birth defects, diabetes, renal disease, osteoporosis, neuropsychiatric disorders, and cancer. We review here the correlation between homocysteine metabolism and the disorders described above with genetic variants on genes coding for enzymes of homocysteine metabolism relevant to clinical practice, especially common variants of the MTHFR gene, 677C>T and 1298A>C. We also discuss the management of hyperhomocysteinemia with folic acid supplementation and fortification of folic acid and the impact of a decrease in the prevalence of congenital anomalies and a decline in the incidence of stroke mortality.

Plasma homocysteine in adolescents depends on the interaction between methylenetetrahydrofolate reductase genotype, lipids and folate: a seroepidemiological study

Background

Many publications link high homocysteine levels to cardiovascular disease. In Spain there is little information on the prevalence of hyperhomocysteinaemia and associated vitamin factors among the general population, and less still among children. Cardiovascular risk factors in the childhood population may be related to the appearance of cardiovascular disease at adult age. The aim of this study is to establish a definition of hyperhomocysteinaemia in adolescents and to analyze the influence of vitamin and metabolic factors in homocysteine levels in this population group.

Methods

Descriptive, cross-sectional epidemiological study to estimate serum homocysteine, vitamin B12 and folate levels, as well as plasma total, HDL- and LDL- cholesterol in a schoolgoing population aged 13 to 17 years in Madrid, Spain.

Spearman correlation analysis was performed to ascertain quantitative comparison, Pearson's χ2 test (frequency < 5, Fisher) was used for comparison of prevalences, Mann-Whitney U and Kruskal-Wallis test were used for comparison of means and Bonferroni correction was used for post-hoc tests. A multivariate logistic regression model was performed in the multivariate analysis.

Results

Based on the classic values for definition of hyperhomocysteinaemia in adults, prevalence of hyperhomocysteinaemia in the study population was: 1.26% for 15 μmol/L; and 2.52% for 12 μmol/L.

Deficits in HDL cholesterol and serum folate levels yielded adjusted Odds Ratios (OR) for hyperhomocysteinemia of 2.786, 95% CI (1.089-7.126), and 5.140, 95% CI (2.347-11.256) respectively. Mutation of the methylenetetrahydrofolate reductase (MTHFR) C677T genotype also raises the risk of hyperhomocysteinaemia (CC→CT: OR = 2.362; 95% CI (1.107-5.042) CC→TT: OR = 6.124, 95% CI (2.301-16.303))

Conclusion

A good definition of hyperhomocysteinaemia in adolescents is the 90^th percentile, equivalent to 8.23 μmol/L. Risk factors for hyperhomocysteinaemia are cHDL and folate deficiency, and the MTHFR C677T mutant genotype. No significant effect could be assessed for vitamin B₁₂. Coexistence of all three factors increases the risk of suffering from hyperhomocysteinaemia 87-fold.

Pharmacogenetics of the neurodevelopmental impact of anticancer chemotherapy

Pharmacogenetics holds the promise of minimizing adverse neurodevelopmental outcomes of cancer patients by identifying patients at risk, enabling the individualization of treatment and the planning of close follow-up and early remediation. This review focuses first on methotrexate, a drug often implicated in neurotoxicity, especially when used in combination with brain irradiation. The second focus is on glucocorticoids that have been found to be linked to adverse developmental effects in relation with the psychosocial environment. For both examples, we review how polymorphisms of genes encoding enzymes involved in specific mechanisms of action could moderate adverse neurodevelopmental consequences, eventually through common final pathways such as oxidative stress. We discuss a multiple hit model and possible strategies required to rise to the challenge of this integrative research.