Association of combined GIF290T>C heterozygous mutation/FUT2 secretor variant with neural tube defects.

Folate and vitamin B12 are needed for the proper embryo-fetal development possibly through their interacting role in the 1-carbon metabolism. Folate fortification reduces the prevalence of complex birth defects, and more specifically neural tube defects (NTDs). GIF and FUT2 are 2 genes associated with the uptake and blood level of vitamin B12. We evaluated GIF and FUT2 as predictors of severe birth defects, in 183 aborted fetuses compared with 375 healthy newborns. The GIF290C allele frequency was estimated to 0.4% in healthy newborns and to 8.1% in NTD fetuses (odds ratio 17.8 [95% confidence interval CI: 4.0-77.6]). The frequency of FUT2 rs601338 secretor variant was not different among groups. The GIF 290C heterozygous/FUT2 rs601338 secretor variant combined genotype was reported in 6 of the 37 NTD fetuses, but not in other fetuses and healthy newborns (P < .0001). This GIF/FUT2 combined genotype has been previously reported in children with congenital gastric intrinsic factor (GIF) deficiency, with respective consequences on B12 binding activity and GIF secretion. In conclusion, a genotype reported in congenital GIF deficiency produces also severe forms of NTD. This suggests that vitamin B12 delivery to neural tissue by the CUBN/GIF pathway could play a role in the neural tube closure mechanisms.

A non-synonymous polymorphism in galectin-3 lectin domain is associated with allergic reactions to beta-lactam antibiotics.

Genetic predictors of beta-lactam (BL) allergy are mostly related to Immunoglobulin E (IgE) synthesis and atopy. Despite this context, little attention has been devoted to genes of IgE/FcɛRI pathway, such as galectin-3, a ß-galactoside-binding lectin, which binds to IgE. We evaluated the association of LGALS3 polymorphisms with BL allergy in 395 Spanish and 198 Italian cases, compared with 310- and 339-matched controls, respectively. The rs11125 predicted BL allergy with an odds ratio of 4.0 in Spanish population (P<0.0001). This association was replicated with an odds ratio of 5.1 in Italian population (P<0.0001); rs11125 predicted also increased serum level of total IgE in Spanish controls. These data are consistent with the predicted deleterious influence of Gln>His substitution produced by rs11125 on galactose-binding activity of galectin-3. In conclusion, LGALS3 is the strongest genetic predictor of BL allergy reported so far. This association reflects the influence of genes of IgE/FcɛRI pathway in this pathology.

Comparison of cytokine gene polymorphism in drug-induced maculopapular eruption, urticaria and drug reaction with eosinophilia and systemic symptoms (DRESS).

BACKGROUND: Polymorphisms of genes controlling cytokine production have not been studied in the genetic susceptibility to cutaneous adverse drug reactions (CADR). OBJECTIVES: The objective was to determine whether polymorphisms in nine cytokine genes were associated to the occurrence of drug reaction with eosinophilia and systemic symptoms (DRESS) compared to drug-induced maculopapular eruption or urticaria and to controls without drug intolerance. METHODS: Results from 118 patients with a well-defined CADR were compared to 236 controls without drug intolerance living in the same area of France. We assessed nine polymorphisms: interleukin (IL)1-alpha-889C>T (rs 1800587), IL1-beta-511C>T (rs 16944), IL1-RN intron-2-VNTR (rs2234663), IL2-330T>G (rs 2069762), IL4-33C>T (rs 2070874), IL5-745C>T (rs 2069812), IL10-592C>A (rs 1800872), IL16-295T>C (rs 4778889) and tumour necrosis factor-alpha-308G>A (rs 1800629). RESULTS: Three polymorphisms exhibited a significant association with CADR (P < 0.05). The combination of the IL1-RN-A2 and IL1-beta-511C alleles was statistically different between cases and controls (P = 0.007) and the A2C haplotype was associated with susceptibility to CADR, particularly in drug reaction with eosinophilia and systemic symptoms (DRESS) patients (odds ratio = 3.22; 95% confidence interval = 1.23-8.41; P = 0.016). The frequency of the IL10-592A allele was higher in DRESS patients than in controls (dominant model CC vs. CA + AA: P = 0.035). These abnormalities were not evident in maculopapular eruptions or urticaria. CONCLUSIONS: This is the first study showing that IL1-cluster polymorphisms and haplotypes and the IL10-592A allele (a low IL10 producer) are associated with DRESS. These gene variants may decrease drug tolerance and promote herpes virus reactivation.

Prevalence of IgE against neuromuscular blocking agents in hairdressers and bakers.

BACKGROUND: Allergic IgE-mediated reactions to neuromuscular blocking agents (NMBAs) are the main cause of immediate hypersensitivity reactions in anaesthesia; their predominant occurrence in the absence of previous exposure to NMBAs suggests a risk related to environmental exposure. OBJECTIVE: To investigate the prevalence of specific IgE to quaternary ammonium ions in two populations professionally exposed to quaternary ammonium compounds, in the north-eastern France. METHODS: The study had a retrospective follow-up design whereby apprentices were assessed after their 2-year training period as apprentices. The professionally exposed hairdresser populations (n = 128) were compared with baker/pastry makers (n = 108) and 'non-exposed' matched control subjects (n = 379). RESULTS: We observed a 4.6-fold higher frequency of positive IgE against quaternary ammonium ions in hairdressers (HD), compared with baker/pastry makers (BP) and control (C) groups. The competitive inhibition of quaternary ammonium Sepharose radioimmunoassay (QAS-IgE RIA) with succinylcholine was significantly higher in HD, compared with BP and C groups, with inhibition percentage of 66.2 ± 7.4, 39.7 ± 6.0 and 43.8 ± 9.9, respectively (P < 0.001). The specific IgE against quaternary ammonium ions recognized also two compounds widely used by hairdressers, benzalkonium chloride and polyquaternium-10, in competitive inhibition of IgE RIA. When considering the whole study population, hairdresser professional exposure and total IgE > 100 kU/L were the two significant predictors of IgE-sensitization against quaternary ammonium ions in the multivariate analysis of a model that included age, sex, professional exposure, increased concentration of total IgE (IgE > 100 kU/L) and positive IgE against prevalent allergens (Phadiatop(®) ; P = 0.019 and P = 0.001, respectively). CONCLUSION AND CLINICAL RELEVANCE: The exposure to hairdressing professional occupational factors increases IgE-sensitization to NMBAs and quaternary ammonium ion compounds used in hairdressing. Besides the pholcodine hypothesis, our study suggests that repetitive exposure to quaternary ammonium compounds used in hairdressing is a risk factor for NMBAs sensitization.

Advanced phenotyping in hypersensitivity drug reactions to NSAIDs.

Non-steroidal anti-inflammatory drugs (NSAIDs) are the medications most frequently involved in hypersensitivity drug reactions. Because NSAIDs are prescribed for many conditions, this is a world-wide problem affecting patients of all ages. Various hypersensitivity reactions have been reported, mainly affecting the skin and/or the respiratory airways. The most frequent of these is acute urticaria, which can be induced by several different NSAIDs. Both specific and non-specific immunological pathways have been proposed as underlying mechanisms. This review presents the clinical phenotypes and the drugs involved in NSAID hypersensitivity. Five major clinical syndromes can be distinguished: aspirin-exacerbated respiratory disease (AERD), aspirin-exacerbated cutaneous disease (AECD), multiple NSAID-induced urticaria/angioedema (MNSAID-UA), single NSAID-IgE reactions and single NSAID T cell responses. However, further classification is possible within these five major entities, by detailed descriptions of the clinical characteristics enabling more phenotypes to be defined. This detailed differentiation now seems required in order to undertake appropriate pharmacogenetic studies.

Allergy to betalactams and nucleotide-binding oligomerization domain (NOD) gene polymorphisms.

BACKGROUND: Polymorphisms of interleukin genes related to IgE production and inflammation are predictors of hypersensitivity to betalactam, but nothing is known on the influence of NOD genes, despite their association with inflammation and atopy. OBJECTIVE: To evaluate the association of NOD2 and NOD1 polymorphisms with betalactam allergy. METHOD: We genotyped 3 polymorphisms of NOD2 and 1 of NOD1 in 368 Italian and 387 Spanish patients, compared with 368 and 326 controls, respectively. RESULTS: CT/TT genotypes of rs2066845 of NOD2 predicted a lower risk in Italy (P = 0.003), while WT/insC genotype of rs5743293 (also in leucine-rich repeat domain) predicted a higher risk in Spain (P = 0.007). G allele of rs2066845 was associated with a higher level of IgE in the Italian population. CONCLUSION: The mirrored influence of these NOD2 polymorphisms on betalactam allergy in two populations suggests a link with pathways of inflammation and/or atopy through mechanisms, which need to be clarified.

Maternal opioid addiction: A potential cause of elevated 17-OH progesterone in neonatal screening.

BACKGROUND: Congenital adrenal hyperplasia (CAH) is a disease that is part of neonatal screening. There are many causes of false-positive results on neonatal screening, and maternal opioid consumption during pregnancy is suspected to increase 17-hydroxyprogesterone (17-OHP) levels at birth. The aim of this study was to determine the effect of maternal drug consumption on 17-OHP values on neonatal screening. MATERIAL AND METHODS: We studied 17-OHP levels of term newborns with reported maternal drug consumption born at the Maternity Hospital of Nancy between 2002 and 2018. These infants were matched with newborns of mothers without drug addiction. The 17-OHP levels, withdrawal syndromes, birth parameters, and maternal characteristics were compared between the two groups. RESULTS: The study included 241 patients (121 in the drug-exposed group, 120 in the control group). The mean 17-OHP levels in newborns of mothers with substance addiction were 9.83 nmol/L compared to 4.90 nmol/L (p=0.0001) in the control group. Newborns exposed to drugs were smaller (p=0.0001), lighter (p=0.0001), had smaller head circumference (p=0.0001), and had lower Apgar scores (p=0.004 at 1 min and p=0.0001 at 5 min). The 17-OHP level did not differ in cases of withdrawal syndrome in drug-exposed newborn (p=0.911). CONCLUSION: A significant increase in 17-OHP levels was observed in newborns exposed to drugs, with no influence of withdrawal syndrome on 17-OHP levels. Maternal substance addiction may be associated with moderately increased 17-OHP levels during neonatal screening.

Genetic variants of the arachidonic acid pathway in non-steroidal anti-inflammatory drug-induced acute urticaria.

BACKGROUND: To date, genetic studies of hypersensitivity reactions to non-steroidal anti-inflammatory drugs (NSAIDs) have been carried out mainly in aspirin-induced asthma and to a lesser extent in chronic urticaria, with no studies in patients with acute urticaria (AU), the most common entity induced by these drugs. OBJECTIVE: In this work, we analysed the association of common variants of 15 relevant genes encoding both enzymes and receptors from the arachidonic acid (AA) pathway with NSAID-induced AU. METHODS: Patients were recruited in several Allergy Services that are integrated into the Spanish network RIRAAF, and diagnosed of AU induced by cross-intolerance (CRI) to NSAIDs. Genotyping was carried out by TaqMan allelic discrimination assays. RESULTS: A total of 486 patients with AU induced by CRI to NSAIDs and 536 unrelated controls were included in this large Spanish case-control study. Seven variants from 31 tested in six genes were associated in a discovery study population from Malaga (0.0003 ≤ p-value ≤ 0.041). A follow-up analysis in an independent sample from Madrid replicated three of the SNPs from the ALOX15 (rs7220870), PTGDR (rs8004654) and CYSLTR1 (rs320095) genes (1.055x10(-6) ≤meta-analysis p-value ≤ 0.003). CONCLUSIONS AND CLINICAL RELEVANCE: Genetic variants of the AA pathway may play an important role in NSAID-induced AU. These data may help understand the mechanism underlying this disease.

Biological and genetic determinants of atopy are predictors of immediate-type allergy to betalactams, in Spain.

BACKGROUND: Betalactam (BL) immediate-type allergy is influenced by environmental and genetic determinants, as illustrated by differences in worldwide prevalence and ethnicity from a same area and by associations with genes related to atopy. AIMS: To evaluate the association of atopy with BL allergy. MATERIALS AND METHODS: We measured specific Immunoglobulin E (IgE) against prevalent allergens and genetic predictors of atopy, IL13, IL4, IL4RA, IL4, and TNFA, in 340 patients and 340 controls from South of Spain. RESULTS: Total IgE and IgE against mites were at higher concentration in patients. Patients with high total IgE and IgE against prevalent allergens had a slower decrease in BL IgE than nonatopic patients. IL4RA I50V and Q551R were associated with IgE against prevalent allergens and total IgE, respectively, and were also predictors of BL allergy. CONCLUSION: Interacting determinants of atopy, total IgE, IgE against prevalent allergens, and IL4RA polymorphisms, contribute to the high prevalence of BL allergy in South of Spain.

Recognition of iodixanol by dendritic cells increases the cellular response in delayed allergic reactions to contrast media.

BACKGROUND: Delayed reactions to iodine contrast media (CM) account for 1-3% of patients with adverse reactions to iodine CM. The cellular and molecular mechanisms of these reactions remain poorly documented. Although most of these reactions are T cell mediated, the involvement of dendritic cells (DC) has not been investigated sufficiently. OBJECTIVE: To determine whether the T cell response to iodixanol requires DC as antigen-presenting cell and, more particularly, to evaluate the changes induced by iodixanol on DC maturation and in vitro production of cytokines after drug stimulation in patients with maculopapular exanthema. METHODS: Peripheral blood lymphocytes, immature monocyte-derived DC (imDC) and skin biopsies were obtained from patients with delayed reactions to iodixanol and tolerant subjects. We studied the consequences of the interaction between DC, lymphocytes and iodixanol by phenotype analysis, proliferation and cytokine production. RESULTS: A T-cell-mediated reaction was evidenced in patient biopsies, with a lymphocyte-rich, peri-vascular infiltrate. Iodixanol induced maturation of imDC from patients but not from controls, with expression of the co-stimulatory markers CD83, CD86 and CD40 and an increase in mean fluorescence intensity of CD80, CD86 and HLA-DR. In the absence of DC, positive cell proliferation to iodixanol was detected in only one patient while the addition of DC produced a positive test in five of the six patients. Similarly, the increase in cytokines (IFN-γ, IL-2, IL-6, IL-1b and TNF-α) was higher when imDC were introduced into the culture together with the culprit drug. CONCLUSION AND CLINICAL RELEVANCE: These results provide evidence for a DC-mediated mechanism in delayed allergic reactions to CM, influencing T cell proliferation and cytokine production. These new insights will be helpful for designing immunotherapeutic strategies and in vitro diagnostic tests of CM-delayed reactions.

Association of tumor necrosis factor-alpha -308G>A polymorphism with IgE-mediated allergy to betalactams in an Italian population.

Tumor necrosis factor-alpha (TNF-alpha) is released from mast cells via an immunoglobulin E (IgE)-dependent mechanism. The variant G>A at -308 of TNFA is part of an extended haplotype HLA-A1-B8-DR3-DQ2 and influences the gene expression. We evaluated this variant in relation to IgE-mediated reactions to betalactams, in 427 subjects, including 167 cases and 260 age- and gender-paired controls. TNFA GG genotype was a significant independent predictor of the primary risk of betalactam allergy, concurrently with total IgE level, with an age- and sex-adjusted odds ratio estimated at 2.45 (95% confidence interval: 1.18-5.08, P=0.0163). Cases with -308AA genotype had a higher serum level of specific IgE than those with -308GA/GG genotype, with median levels (relative units) of 4.6 (inter-quartiles: 3.9-10.6) and 2.2 (1.4-4.3), respectively (P=0.0046). In conclusion, our results suggest an ambivalent influence of a genetic determinant of pro-inflammatory pathways on IgE-mediated hypersensitivity to betalactams.

Left ventricular systolic dysfunction is an independent predictor of homocysteine in angiographically documented patients with or without coronary artery lesions.

BACKGROUND: Elevated plasma homocysteine is a risk factor for coronary artery disease (CAD) and thromboembolic disorders that seems also to be associated with chronic heart failure. OBJECTIVE: To evaluate the association between homocysteine and left ventricular dysfunction and to assess whether it is independent of CAD. PATIENTS AND METHODS: A prospective study evaluated this relationship in 709 patients referred for diagnostic coronary angiography, including 515 CAD and 194 patients without evidence of coronary artery lesions. RESULTS: The homocysteine level was significantly higher in the 187 patients with a left ventricular ejection fraction (LVEF) dysfunction < 40% (P < 0.0001) than in those without ventricular dysfunction. LVEF, NYHA functional class II or III and CAD, stable angina and hypertension were clinical characteristics that influenced total homocysteine level in univariate analysis. Homocysteine was significantly associated with LVEF and N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) in univariate regression (r = -0.267, 95% CI -0.33 to -0.19, P < 0.0001, and r = 0.381, 95% CI 0.28-0.47, P < 0.0001, respectively) and in multiple regression (P = 0.0022 and P = 0.0001, respectively). Other determinants were creatinine and vitamin B(12), but not folate. LVEF was a predictor of homocysteine > 15 micromol L(-1) in the whole population (P for trend < or = 0.0001) and in patients without documented CAD (P for trend = 0.0058). CONCLUSION: Our results showed an association of homocysteine with left ventricular systolic dysfunction and NT-pro-BNP that existed independently of documented CAD. Whether this association reflects a causative factor or a consequence of CHF and influences the prognosis of the disease remains an open question.

Transcobalamin and methionine synthase reductase mutated polymorphisms aggravate the risk of neural tube defects in humans.

The pathogenic mechanism of neural tube defects may involve genetic polymorphisms and nutritional factors related to homocysteine metabolism. We evaluated the association of polymorphisms of three genes affecting vitamin B12-dependent remethylation of homocysteine, transcobalamin (TC), methionine synthase (MTR) and MTR reductase (MTRR), combined or not with methylenetetrahydrofolate reductase (MTHFR), with the risk of having neural tube defect in 40 children with spina bifida and 58 matched controls from South Italy. MTR 2756 AG/GG, TC 777 CG/GG /MTHFR 677 CC and MTRR 66 GG /MTHFR 677 CC genotypes increased the risk with odds ratios of 2.6 (P=0.046), 2.4 (P=0.028) and 4.5 (P=0.023), respectively. In contrast, MTHFR 677 TT was protective (odds ratio=0.11, P=0.009). In conclusion, genetic determinants affecting the cellular availability or MTRR-dependent reduction of B12 may increase the risk of spina bifida.

Homocysteine predicts increased NT-pro-BNP through impaired fatty acid oxidation.

BACKGROUND: The deficiency in methyl donors, folate and vitamin B12, increases homocysteine and produces myocardium hypertrophy with impaired mitochondrial fatty acid oxidation and increased BNP, through hypomethylation of peroxisome-proliferator-activated-receptor gamma co-activator-1α, in rat. This may help to understand better the elusive link previously reported between hyperhomocysteinemia and BNP, in human. We investigated therefore the influence of methyl donors on heart mitochondrial fatty acid oxidation and brain natriuretic peptide, in two contrasted populations. METHODS: Biomarkers of heart disease, of one carbon metabolism and of mitochondrial fatty acid oxidation were assessed in 1020 subjects, including patients undergoing coronarography and ambulatory elderly subjects from OASI cohort. RESULTS: Folate deficit was more frequent in the coronarography population than in the elderly ambulatory volunteers and produced a higher concentration of homocysteine (19.3 ± 6.8 vs. 15.3 ± 5.6, P<0.001). Subjects with homocysteine in the upper quartile (≥ 18 µmol/L) had higher concentrations of NT-pro-BNP (or BNP in ambulatory subjects) and of short chain-, medium chain-, and long chain-acylcarnitines, compared to those in the lower quartile (≤ 12 µmol/L), in both populations (P<0.001). Homocysteine and NT-pro-BNP were positively correlated with short chain-, medium chain-, long chain-acylcarnitines and with acylcarnitine ratios indicative of decreased mitochondrial acyldehydrogenase activities (P<0.001). In multivariate analysis, homocysteine and long chain acylcarnitines were two interacting determinants of NT-pro-BNP, in addition to left ventricular ejection fraction, body mass index, creatinine and folate. CONCLUSIONS: This study showed that homocysteine predicts increased NT-pro-BNP (or BNP) through a link with impaired mitochondrial fatty oxidation, in two contrasted populations.

Perioperative anaphylaxis.

The incidence of immune-mediated anaphylaxis during anesthesia ranges from 1 in 10,000 to 1 in 20,000. Neuromuscular blocking agents are most frequently incriminated, followed by latex and antibiotics, although any drug or substance used may be a culprit. Diagnosis relies on tryptase measurements at the time of the reaction and skin tests, specific immunoglobulin E, or basophil activation assays. Treatment consists of rapid volume expansion and epinephrine administration titrated to symptom severity.

Perioperative anaphylaxis.

The incidence of immune-mediated anaphylaxis during anesthesia ranges from 1 in 10,000 to 1 in 20,000. Neuromuscular blocking agents represent the most frequently involved substances, followed by latex and antibiotics, but every drug or substance used may be involved. Diagnosis relies on tryptase measurements at the time of the reaction and skin tests and specific IgE or basophil activation assays.

Pharmacogenetic determinants of immediate and delayed reactions of drug hypersensitivity.

Drug allergy refers to a hypersensitivity reaction for which either an IgE or T-cell-mediated mechanism is demonstrated. The recognition of the drug by B and T cells is influenced by variants of HLA genes. The genetic factors involved in IgE-mediated mechanisms have been studied mainly in beta-lactam reactions, and they appear to be related to human leukocyte antigen presentation (HLA A2 and DRw52), TNFA -308G>A, class switching to IgE by B cells (variants of IL-13 and of IL-4RA), and expression of IgE receptors on target cells (variant of the FcepsilonRIbeta gene). Delayed T-cell-mediated reactions are also associated with HLA alleles. Studies have reported an association of HLA-B*1502 and HLA-B*5801 in patients with the Stevens-Johnson syndrome or toxic epidermal necrolysis provoked by carbamazepine, as well as of HLA-B*5701 with abacavir hypersensitivity. HLA-B*5701 seems to be a strong predictor in whites, but not in Hispanics or Africans. Carbamazepine hypersensitivity is also influenced by gene variants of cytochrome P450 enzymes on the generation of reactive metabolites, while CYP2C9*2 and CYP2C9*3 polymorphisms influence the bioactivation of sulfamethoxazole in prohapten. Pharmacogenetic studies on aspirin hypersensitivity have identified distinct types of predictors, such as HLA genotypes, a polymorphism in the promoter of the FcepsilonRIalpha gene, and variants in genes of enzymes from the arachidonic acid pathway. In the future, identification of genetic predictors will benefit from genomewide association studies that also take ethnic differences into account. Ideally, predictors will help to prevent adverse reactions, as suggested by a recent study on the effectiveness of prospective HLA-B*5701 screening to prevent hypersensitivity reactions to abacavir in HIV patients.

Hypersensitivity reactions to neuromuscular blocking agents.

Neuromuscular blocking agents are the leading drugs responsible for immediate hypersensitivity reactions during anaesthesia. Most hypersensitivity reactions represent IgE-mediated allergic reactions. Their incidence is estimated to be between 1 in 3,000 to 1 in 110,000 general anaesthetics. However striking variations have been reported among countries. The mechanism of sensitisation seems to implicate the presence of a substituted ammonium ion in the molecule. Due to lack of exposure prior to the reaction in a large number of reactors, it has been hypothesised that sensitisation may involve other, as yet undefined, substituted (quaternary and tertiary) ammonium ion containing compounds such as pholcodine, present in the environment of the patient. This hypothesis is still under investigation. The mechanism of non-IgE mediated hypersensitivity reactions is less well known. Identified mechanisms correspond to direct histamine release or interactions with muscarinic and nicotinic receptors. Allergic reactions cannot be clinically distinguished from non-IgE-mediated reactions. Therefore, any suspected hypersensitivity reaction must be investigated using combined pre and postoperative testing. Because of the frequent but not systematic cross-reactivity observed with muscle relaxants, every available neuromuscular blocking agent should be tested, using intradermal tests to confirm the responsibility of the suspected drug which should be definitely excluded. Cross-sensitivity investigation will also try to identify the safety of drugs that can be potentially used in future anaesthesia. The determination of basophil activation investigations using direct leukocyte histamine release test or flow cytometry would be of particular interest to investigate cross sensitisation in complement to skin tests. There is no demonstrated evidence supporting systematic pre-operative screening in the general population at this time. However, since no specific treatment has been shown to reliably prevent anaphylaxis, allergy assessment must be performed in all high-risk patients. In view of the relative complexity of allergy investigation, and of the differences between countries, an active policy to identify patients at risk and to provide any necessary support from expert advice to anaesthetists and allergologists through the constitution of allergo-anaesthesia centres in every country should be promoted.

Impact of folate and homocysteine metabolism on human reproductive health.

Folates belong to the vitamin B group and are involved in a large number of biochemical processes, particularly in the metabolism of homocysteine. Dietary or genetically determined folate deficiency leads to mild hyperhomocysteinemia, which has been associated with various pathologies. Molecular mechanisms of homocysteine-induced cellular dysfunction include increased inflammatory cytokine expression, altered nitric oxide bioavailability, induction of oxidative stress, activation of apoptosis and defective methylation. Whereas the involvement of folate metabolism and homocysteine in ageing-related diseases, in several developmental abnormalities and in pregnancy complications has given rise to a large amount of scientific work, the role of these biochemical factors in the earlier stages of mammalian reproduction and the possible preventive effects of folate supplementation on fertility have, until recently, been much less investigated. In the present article, the possible roles of folates and homocysteine in male and female subfertility and related diseases are systematically reviewed, with regard to the epidemiological, pathological, pharmacological and experimental data of the literature from the last 25 years.