Reduced Folate Carrier 1 A80G Research Articles

Folate gene polymorphisms CBS 844ins68 and RFC1 A80G and risk of Down syndrome offspring in young Iranian women: A cross-sectional study

Background: Cytogenetics and association studies showed that folate gene polymorphisms can increase the risk of chromosomal nondisjunction and aneuploidies. The folate-metabolizing gene polymorphisms in Down syndrome mothers (DSM) have been assessed in a variety of populations. Reduced folate carrier 1 (RFC1) and cystathionine beta-synthase (CBS) are key enzymes in folate metabolism.
 Objective: 2 common polymorphisms, CBS 844ins68 and RFC1 A80G, were analyzed to determine their probable risk for having Down syndrome (DS) babies in young mothers of Khuzestan province, Iran.
 Materials and Methods: This study was conducted on 100 mothers who had trisomy 21 DS children. 100 age- and ethnic-matched mothers with at least 2 healthy children and no history of abnormal pregnancies were considered as control. The samples were collected from all the mothers from June 2019 to April 2021. Genomic DNA was extracted from peripheral blood. The CBS-844ins68 and RFC1-A80G were genotyped using polymerase chain reaction-electrophoresis and restriction fragment length polymorphism, respectively.
 Results: The frequency of RFC1 AG and GG genotypes in DSM was significantly higher than the control mothers (odds ratio [OR] of 2.38 and 3.07, respectively). The heterozygote genotype of CBS 844ins68 was significantly more prevalent among DSM than the control (OR: 2.419). The OR was significantly increased to 6.667 when the homozygote of both variants was found together.
 Conclusion: Studying polymorphisms possibly increases the susceptibility of having a DS child. However, ethnicity, nutrition, and epistatic interactions are considerable factors to be evaluated in future studies.
 Key words: Down syndrome, Folic acid, Polymorphism, CBS, RFC1.

The Roles of Reduced Folate Carrier-1 (RFC1) A80G (rs1051266) Polymorphism in Congenital Heart Disease: A Meta-Analysis

BackgroundWe performed the present study to better elucidate the correlation of reduced folate carrier-1 (RFC1) A80G (rs1051266) polymorphism with the risk of congenital heart disease (CHD).Material/MethodsAccording to the designed search strategy, a systematic literature search was performed through the PubMed, Cochrane Library, Web of Science, EMBASE, CNKI, VIP, and Wan Fang databases to collect published case-control studies on the correlation between RFC1 A80G polymorphism and CHD. All relevant studies up to October 1, 2019 were identified. The odds ratio (OR) and 95% confidence interval (CI) of the genotype distribution were used as the effect indicators.ResultsA total of 6 eligible studies was finally included in our meta-analysis, including 724 children with CHD, 760 healthy children, 258 mothers of the children with CHD, and 334 mothers of healthy control children. The meta-analysis revealed that for fetal analysis, only in the heterozygous model (GA vs GG, OR=1.36, 95% CI [1.06, 1.75], P=0.02) was RFC1 A80G polymorphism associated with risk of CHD. In maternal analysis, 3 genetic models of RFC1 A80G polymorphism increased the risk of CHD: the allelic model (A vs G, OR=1.36, 95% CI [1.07, 1.71], P=0.01), the homozygote model (AA vs GG, OR=2.99, 95%CI [1.06, 8.41], P=0.04), and the dominance model (GA+AA vs GG, OR=1.53, 95%CI [1.08, 2.16], P=0.02).ConclusionsThe maternal RFC1 A80G polymorphism has a strong correlation with CHD. Compared with the G allele, the A allele increases the risk of CHD by 0.36-fold.

Association of methylenetetrahydrofolate reductase C677T and reduced-f carrier-1 G80A gene polymorphism with preeclampsia in Sudanese women

ABSTRACT Purpose To assess the associations between preeclampsia, methylenetetrahydrofolate reductase (MTHFR) C677T, and reduced folate carrier-1 (RFC-1) G80A gene polymorphism in Sudanese women. Methods A matched (for age and parity) case–control study was conducted in a tertiary hospital (Saad Abualila) in Khartoum, Sudan during February to September 2018. The cases were women with preeclampsia and healthy pregnant women were the controls (160 women in each arm of the study). Genotyping for MTHFR C677T and RFC-1 G80A was performed by polymerase chain reaction–restriction fragment length polymorphism. Results . . The MTHFR C677T variation was significantly more frequent in women with preeclampsia (16.2%) than in healthy pregnant women (1.8%) (OR = 10.1, 95% CI = 3.0–34.2, P < 0.001). There was borderline significance in the RFC-1 G80A variation, which was present in 2.50% of women with preeclampsia, but was not found in healthy pregnant women (P = 0.052). Conclusion s: A higher prevalence of MTHFR C677T polymorphism in women with preeclampsia compared with healthy pregnant women suggests involvement of this variation in preeclampsia in Sudan.

Association between RFC1 A80G polymorphism and the susceptibility to nonsyndromic cleft lip with or without cleft palate: a meta-analysis.

Reduced folate carrier 1 (RFC1) gene is a candidate for susceptibility to nonsyndromic cleft lip with or without cleft palate (NSCL/P). Association between RFC1 A80G polymorphism and NSCL/P have been studied. The published results are conflicting. A meta-analysis of the association between RFC1 A80G polymorphism and NSCL/P was carried out using Stata13.0. A systematic literature search was performed through the PubMed, EMBASE, the Cochrane Library, Web of Science, ScienceDirect, EBSCOhost, China Biology Medicine databases, China National Knowledge Infrastructure and the Wanfang databases. All relevant studies up to 9 September 2019 were identified. Nine case-control studies including 4,229 total participants (1,334 NSCL/P children, 1,515 healthy children, 656 mothers of the NSCL/P children, and 724 mothers of healthy control children) were included in this study. The meta-analysis revealed that two genetic models of RFC1 A80G polymorphism in NSCL/P children increased risk of NSCL/P: the homozygote model (GG vs. AA, OR =2.346, 95% CI: 1.127-4.884) and the recessive model (GG vs. AG + AA, OR =1.503, 95% CI: 1.049-2.152). Further sensitivity analysis indicated that the frequency of G allele and GG genotype in NSCL/P children was significantly higher than those in the control. However, there was no significant statistical differences after Bonferroni correction. Subgroup analyses indicated the presence of the association of all the model with NSCL/P risk in the Indian children. RFC1 A80G polymorphism in the maternal population of NSCL/P children was not significantly associated with children NSCL/P. The RFC1 A80G polymorphism was a candidate for susceptibility to NSCL/P in the Indian pediatric population. More studies with larger samples are necessary to reach more conclusive outcomes.

PREVALENCE OF GLUTAMATE CARBOXYPEPTIDASE II C1561T, REDUCED FOLATE CARRIER 1 A80G, AND METHIONINE SYNTHASE A2756G GENE POLYMORPHISMS IN PATIENTS WITH TYPE 2 DIABETES MELLITUS AMONG SOUTH INDIANS

Objective: Glutamate carboxypeptidase II (GCPII), reduced folate carrier 1 (RFC1), and methionine synthase (MTR) genes involved in the folate metabolic pathway may play a key role in the pathogenesis of diabetes and its complications. The present study aimed to investigate the prevalence of genetic polymorphisms of GCPII C1561T, RFC1 A80G, and MTR A2756G in individuals with type 2 diabetes mellitus (T2DM) among South Indians.&#x0D; Methods: The study subjects consisted of 100 healthy individuals and 200 patients with T2DM. Genetic polymorphisms (GCPII C1561T, RFCI A80G, and MTR A2756G) in the folate metabolic pathway were analyzed by polymerase chain reaction-restriction fragment length polymorphism method. Statistical analysis was performed to test the level of significance.&#x0D; Results: With regard to GCPII C1561T and MTR A2756G gene polymorphisms, significant differences were not found when diabetic patients (with and without complications) and controls were compared according to different statistical models (dominant, recessive, and overdominant) p&gt;0.05. A case–control genetic association analysis of RFC1 A80G gene polymorphism has shown that there was 3.7-fold increased risk for patients without complications and 4.9-fold increased risk for diabetic patients with complications.&#x0D; Conclusions: Our findings suggest that the GCPII C1561T and MTR A2756G gene polymorphisms were not significantly associated with diabetes and its complications. Whereas, the RFCI A80G gene polymorphism involved in folate metabolism confers increased risk for diabetes and its complications in South Indian population.

Association of MTHFR and RFC1 gene polymorphisms with methotrexate efficacy and toxicity in Chinese Han patients with rheumatoid arthritis.

ObjectiveThe objective was to explore the association of methylene tetrahydrofolate reductase (MTHFR) C667T and A1298C and reduced folate carrier 1 (RFC-1) A80G single nucleotide polymorphisms (SNP) with rheumatoid arthritis (RA) and efficacy and toxicity of methotrexate (MTX) treatment in Chinese Han patients in Henan, China.MethodsTwo hundred ninety-six patients with RA were enrolled (cases) and 120 healthy individuals served as controls. The genotypes of MTHFR C667T and A1298C SNP and RFC-1 A80G SNP were detected by restriction fragment length polymorphism-PCR and compared between cases and controls. We analyzed correlations of clinical effect, toxicity, and SNPs after 6 months of MTX treatment.ResultsWe detected no significant differences in MTHFR C677T and A1298C and RFC-1 A80G SNPs between cases and controls. The RFC-1 A80G SNP differed between RA patients with good and poor efficacy after 6 months of MTX, and was an independent factor of MTX efficacy. The MTHFR C677T SNP was differently distributed in the adverse drug reaction (ADR) and non-ADR groups and was an independent factor of MTX toxicity.ConclusionsIn Chinese Han patients with RA, the MTHFR C667T SNP may correlate with MTX toxicity, whereas the RFC-1 A80G SNP may correlate with MTX efficacy rather than toxicity.

Contribution of genetic polymorphism of methylene tetrahydrofolate reductase on the effect of methotrexate in ectopic pregnancy patients.

BackgroundMethotrexate (MTX) is the prior drug in ectopic pregnancy (EP). However, approximately 10% of patients suffer from failure by MTX therapy. Reduced folate carrier 1 (RFC1), methylene tetrahydrofolate reductase (MTHFR), and dihydrofolate reductase (DHFR) are involved in the transport and effects of MTX in vivo. In the present study, we aim to investigate the relationship between the genetic polymorphisms of RFC1, MTHFR, and DHFR and the clinical efficacy of MTX in tubal pregnancies.Methods100 patients of EP were enrolled in this study. Polymorphisms of RFC1 G80A, MTHFR C677T, and DHFR A‐317G were genotyped. β‐hCG level was detected in day 0, 4, and 7 after MTX injection. Association of MTX efficacy and genetic polymorphisms was analyzed.ResultsMethylene tetrahydrofolate reductase C677T was associated with MTX treatment (P = .017). The success rate of first MTX injection was superior in patients with harboring mutation allele of MTHFR gene than that in patients with wild‐type gene (P = .001). However, there was no significant association between the polymorphisms of RFC1 G80A, DHFR A‐317G, and surgical treatment (P = .709 and .476, respectively). In addition, β‐hCG level decrement was not significantly changed by MTX injection with different polymorphisms of RFC1, MTHFR, and DHFR on either day 4 (P = .214, 0.197 and 0.270, respectively) or day 7 (P = .172, .554, and .726, respectively).ConclusionOur results suggested that the reliable indicator was polymorphism of MTHFR C677T in failure by MTX injection.

The association between reduced folate carrier-1 gene 80G/A polymorphism and methotrexate efficacy or methotrexate related-toxicity in rheumatoid arthritis: A meta-analysis

Methotrexate (MTX), the most commonly used anti-rheumatic drug against RA, enters the cell via the action of the reduced folate carrier 1(RFC1). A major polymorphism of the RFC1 gene, 80G/A, has been reported to influence the activity of RFC1, resulting in variable intracellular MTX-polyglutamate (MTX-PG) levels. However, the association studies addressing the RFC1 80G/A polymorphism and MTX efficacy or toxicity in Rheumatoid arthritis (RA) has yielded conflicting results. In the present meta-analysis, we aimed to evaluate the association between the RFC1 80G/A polymorphism and MTX efficacy or toxicity in RA patients. A total 17 studies met our inclusion criteria. Among them, 12 studies with 2049 subjects reported the association between the RFC1 80G/A and MTX response, and 12 studies involving 2627 subjects were on MTX-related toxicity. Meta-analysis revealed significant association between RFC1 80G/A polymorphism and MTX efficacy (odds ratio (OR) for the A allele=1.29, 95% confidence interval (CI) 1.05–1.67, P=0.02; for AA genotype: OR=1.49, 95%CI 1.17–1.907, P=0.001). However, no association could be detected in the analysis of MTX-related toxicity. Stratification by ethnic population also indicated an association between this polymorphism and MTX efficacy in Asian group (P=0.002 for A allele; P=0.003 for AA genotype), but not in the Caucasian group (P=0.15 for A allele; P=0.05 for AA genotype). In both Asian and Caucasian sub-groups, no influence of the RFC1 80G/A polymorphism on MTX toxicity can be detected. In conclusion, the RFC1 G80A polymorphism is associated with responsiveness to MTX therapy, but may not be associated with MTX toxicity in RA patients.

The association between RFC1 G80A polymorphism and cancer susceptibility: Evidence from 33 studies

Aberrant folate metabolism is closely related to tumorigenesis. Genetic variations in the Reduced folate carrier 1 (RFC1) may alter the progress of folate metabolism, and thereby cause the initiation and progress of the cancer. Considerable studies have performed to investigate the association between RFC1 G80A (rs1051266) polymorphism and cancer susceptibility, but the conclusions were conflicting. Therefore, we conducted a meta-analysis to reevaluate the association of RFC1 G80A polymorphism with cancer risk. PubMed and EMBASE were searched for eligible studies. The association of RFC1 G80A polymorphism and cancer risk was evaluated by the pooled odds ratios (ORs) and corresponding 95% confidence intervals (CIs). The significant association was found between RFC1 G80A polymorphism and hematological malignance susceptibility (A vs. G: OR=1.11, 95%CI=1.003-1.23, P=0.045; GA vs. GG: OR=1.18, 95%CI=1.06-1.31, P=0.002; AA+GA vs. GG: OR=1.18, 95%CI=1.07-1.29, P=0.001). Stratified analysis by ethnicity indicated that the association became more prominent among Caucasians (GA vs. GG: OR=1.28, 95%CI=1.12-1.45, P<0.001; AA+GA vs. GG: OR=1.21, 95%CI=1.08-1.36, P=0.001). In term of the cancer type, this polymorphism significantly increased the risk of acute lymphoblast leukemia (GA vs. GG: OR=1.13, 95%CI=1.001-1.28, P=0.048; AA+GA vs. GG: OR=1.28, 95%CI=1.13-1.46, P<0.001) and acute myeloid leukemia (GA vs. GG: OR=2.57, 95%CI=1.37-4.85, P=0.003). No significant association between RFC1 G80A polymorphism and overall solid cancer risk was observed, but a protective association with digestive cancer risk was found (GA vs. GG: OR=0.89, 95%CI= 0.81-0.99, P=0.030). The comprehensive meta-analysis encouraged the notion that RFC1 G80A polymorphism may play an important role in hematopoietic system malignance. These findings need further validation in the large multicenter investigations.

Relationship between reduced folate carrier gene polymorphism and non-syndromic cleft lip and palate in Indian population

Objective: Folate metabolism involves absorption, transport, modifications and interconversions of folates. The reduced folate carrier does not participate directly in folate metabolism but plays a major role in intracellular transport of metabolically active 5-methyltetrahydrofolate and maintains the intracellular concentrations of folate. The purpose of this study was to identify the prevalence of reduced folate carrier 1 (RFC1) A80G polymorphism and to further delineate its association with non-syndromic cleft lip and palate (NSCLP) in a south Indian population.Methods: In the present case-control study, we studied RFC1 gene A80G polymorphism to evaluate its impact on NSCLP risk in south Indian population. Blood samples of 142 cases with NSCLP and 141 controls were collected and genotyped using PCR-RFLP.Results: The genotype distribution in the control group followed Hardy–Weinberg equilibrium (p = 0.633). The G allele frequency of cases was 64.8% (184/284) and was significantly lower than that found in the control group 56.4% (160/282). The genotype distributions between NSCLP cases and controls was not significantly different (p = 0.131). The allelic model significantly increased the risk of NSCLP (G versus A; OR = 1.40; 95% CI: 1.00–1.97; p = 0.050). In subgroup analysis, the A80G variant showed significant association for the CLP group in dominant and allelic models.Conclusions: Altogether, our findings support the hypothesis that RFC1 A80G variant may contribute to NSCLP susceptibility in a south Indian population.

Polymorphisms in genes RFC-1/CBS as maternal risk factors for Down syndrome in China

To explore the relationship between genetic polymorphisms in reduced folate carrier 1 (RFC-1), cystathionine b-synthase (CBS), two key genes in folate metabolism, and the risk of Down syndrome in China. Genomic DNA was isolated from the peripheral lymphocytes of 104 mothers born children with Down syndrome and 184 age-matched control mothers. Polymerase chain reaction and restriction-fragment length polymorphism were used to examine the polymorphisms of RFC-1 A80G, CBS T833C and the relationship between these genotypes and the risk of Down syndrome was analyzed. We found that there were significant differences between RFC-1 G80G, CBS C833C polymorphisms among mothers of children with Down syndrome than among control mothers, with odds ratio of 1.51 (95 % CI 1.05-2.18), 1.53 (95 % CI 1.07-2.18) respectively. The combined presence of RFC1 mutant alleles and the CBS homozygous mutant allele (15/104) was associated with a 4.81-fold increased risk of having a child with Down syndrome (95 % CI 1.82-12.68, P = 0.0007). We concluded that RFC-1 and CBS gene mutation alleles are related to Down syndrome, and women with mutation RFC-1 G80G, CBS C833C OR combined with RFC-1 A80G and CBS 833TT genotype increase the risk of Down syndrome in China.

Abstract 1874: The role of functional polymorphisms in folate metabolism on 6-mercaptopurine-mediated hematological toxicity in children with acute lymphoblastic leukemia

Abstract Purpose: Defective S-methylation of 6-mercarptopurine (6-MP) either due to reduced activity of thiopurine s-methyltransferase (TPMT) or due to reduced synthesis of S-adenosyl methionine (SAM) induces hematological toxicity in children undergoing 6-MP treatment for acute lymphoblastic leukemia (ALL). Recently, we have demonstrated the genetic variants of TMPT results in hematological toxicity when on 6-MP. In the current study, we have aimed to explore the role of seven functional polymorphisms in folate metabolism as pharmacogenomic determinants of 6-MP mediated toxicity. Experimental Procedures: In 126 children with ALL being treated with 6-MP, Glutamate carboxypeptidase II (GCPII) C1561T, Reduced folate carrier 1 (RFC1) G80A, cytosolic serine hydroxymethyl transferase (cSHMT) C1420T, Thymidylate synthase (TYMS) 3′-UTR ins6/del6, Methylene tetrahydrofolate reductase (MTHFR) C677T, Methionine synthase (MTR) A2756G polymorphisms were analysed by PCR-RFLP method while TYMS 5′-UTR 28 bp tandem repeat analysis was done by PCR-AFLP method. Summary: Univariate analysis showed positive association of GCPII C1561T (r= 0.23) and cSHMT C1420T (r=0.15) variants with hematological toxicity. Multi dimensionality reduction analysis confirmed synergetic gene-gene interaction between these two loci (×2=5.9, p=0.02) apart from showing an interesting tri-variate interaction i.e, RFC1 G80A/cSHMT C1420T/TYMS 5′-2R3R. RFC1 G80A showed additive interaction with cSHMT while TYMS 2R alleles showed counteracting interaction. Toxicity grade prediction model was developed using multiple linear regression approach, which showed moderate predictability of aberrations in folate metabolism and TPMT*3C (Area under the receiver operating characteristic curve=0.69) thus explaining 36% variation in toxicity. Conclusion: Aberrations in folate metabolism and TPMT*3C contribute to 36% 6-MP mediated toxicity. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1874. doi:1538-7445.AM2012-1874

Aberrations in one-carbon metabolism induce oxidative DNA damage in sporadic breast cancer

The authors investigated the role of dietary micronutrients and eight functional polymorphisms of one-carbon metabolism in modulating oxidative stress in sporadic breast cancer. PCR-restriction fragment length polymorphism (RFLP) and PCR-amplified fragment length polymorphism (AFLP) methods were used for genetic analysis in 222 sporadic breast cancer cases and 235 controls. Standardized food frequency questionnaire was used for dietary micronutrient assessment. 8-oxo-2'-deoxyguanosine (8-oxodG), folate, and estradiol were estimated using commercial ELISA kits. Reverse-phase HPLC coupled with fluorescence detector was used for plasma homocysteine analysis. Total glutathione was estimated using Ellman's method. Reduced folate carrier 1 (RFC1) G80A and methylenetetrahydrofolate reductase (MTHFR) C677T were associated with risks of 1.34 (95% CI 1.01-1.79)- and 1.84 (95% CI 1.14-3.00)-folds, respectively, for sporadic breast cancer while cytosolic serine hydroxymethyl transferase (cSHMT) C1420T was associated with reduced risk (OR 0.71, 95% CI 0.53-0.94). Significant increase in plasma 8-oxo-2'-deoxyguanosine (P < 0.004) and homocysteine (P < 0.0001); and significant decrease in total glutathione (P < 0.01) and dietary folate (P = 0.006) was observed in cases than in controls. Oxidative DNA damage showed direct association with menopause (P = 0.02), RFC1 G80A (P < 0.05) and homocysteine (P < 0.0001); and inverse association with dietary folate (P < 0.0001), plasma folate (P < 0.0001), cSHMT C1420T (P < 0.05) and glutathione (P < 0.001). To conclude, the aberrations in one-carbon metabolism induce oxidative stress in sporadic breast cancer either by affecting the folate pool or by impairing remethylation.

A80G polymorphism of reduced folate carrier 1 (RFC1) gene and head and neck squamous cell carcinoma etiology in Brazilian population

Reduced folate carrier is an essential folate transporter and the A80G polymorphism in reduced folate carrier 1 gene (rs1051266) has been shown to be associated with alterations in folate metabolism and consequently cancer development. We evaluated the association of this polymorphism with head and neck squamous cell carcinoma risk in a case-control study of 322 head and neck carcinoma patients and 531 individuals without cancer in a Brazilian population and association of this polymorphism with clinical histopathological parameters, and gender and lifestyle factors. The PCR-RFLP technique was used to genotype the polymorphism and multiple logistic regression was used for comparison between the groups and for interaction between the polymorphism and risk factors and clinical histopathological parameters. We observed association between the RFC1 A80G polymorphism and the risk of this disease. Male gender, tobacco habit and RFC1 AG or GG genotypes may be predictors of this disease (P < 0.05). The genotype, 80AG or GG was associated with for >50 years, male gender and non alcohol consumption (P ≤ 0.05). The polymorphism did not show any association with the primary site, aggressiveness, lymph node involvement or extension of the tumor. In conclusion tobacco and male gender are associated with etiology of this disease and our data provide evidence that supports an association between the RFC1 A80G polymorphism and head and neck squamous cell carcinoma risk, male gender, alcohol non consumption and age over 50 years. However, further studies of folate and plasma concentrations may contribute to the better understanding of the factors involved in the head and neck squamous cell carcinoma etiology.

A80G polymorphism of reduced folate carrier 1 (RFC1) and C776G polymorphism of transcobalamin 2 (TC2) genes in Down's syndrome etiology

There is evidence that polymorphisms of genes involved in folate metabolism may be associated with higher risk that mothers may bear a Down's syndrome (DS) child. This study therefore had the objective of investigating the A80G polymorphism of the reduced folate carrier 1 (RFC1) gene and the C776G polymorphism of the transcobalamin 2 (TC2) gene as maternal risk factors for DS among Brazilian women. Analytical cross-sectional study with control group, at Faculdade de Medicina de São José do Rio Preto (Famerp). Sixty-seven mothers of DS individuals with free trisomy 21, and 113 control mothers, were studied. Molecular analysis of the polymorphisms was performed by means of the polymerase chain reaction with restriction fragment length polymorphism (PCR-RFLP), followed by electrophoresis on 2% agarose gel. The frequencies of the polymorphic alleles were 0.51 and 0.52 for RFC1 80G, and 0.34 and 0.34 for TC2 776G, in the case and control groups, respectively. Thus, there were no differences between the groups in relation to either the allele or the genotype frequency, for both polymorphisms (P = 0.696 for RFC1 A80G; P = 0.166 for TC2 C776G; P = 0.268 for combined genotypes). There was no evidence of any association between the RFC1 A80G and TC2 C776G polymorphisms and the maternal risk of DS in the sample evaluated.

Reduced folate carrier 1 (RFC1) is associated with cleft of the lip only

In this report, we have reanalyzed genotyping data in a collection of families from South America based on maternal origin. Genotyping analysis was performed at the Craniofacial Anomalies Research Center at the University of Iowa. These genotypes were derived from genomic DNA samples obtained from blood spots from children born with isolated orofacial clefts in 45 hospitals located in eight countries (Argentina, Bolivia, Brazil, Chile, Ecuador, Paraguay, Uruguay, and Venezuela) collaborating with ECLAMC (Latin American Collaborative Studies of Congenital Malformations) between January 1998 and December 1999. Dried blood samples were sent by regular mail to the Laboratory of Congenital Malformations, Federal University of Rio de Janeiro. Previous findings suggested that mitochondrial haplotype D is more commonly found among cleft cases born in South America. We hypothesized that association of certain genes may depend upon the ethnic origin, as defined by population-specific markers. Therefore, we tested if markers in MTHFR (5,10-methylenetetrahydrofolate reductase) and RFC1 (reduced folate carrier 1) were associated with oral clefts, depending on the maternal origin defined by the mitochondrial haplotype. Transmission distortion of alleles in MTHFR C677T and RFC1 G80A polymorphic variants was tested in 200 mother/affected child pairs taking into consideration maternal origin. RFC1 variation was over-transmitted to children born with cleft lip only (P = 0.017) carrying mitochondrial DNA haplotypes other than haplotype D. Our results provide a new indication that variation in RFC1 may contribute to cleft lip only. Future studies should investigate the association between oral clefts and RFC1 based on more discrete phenotypes.

Genetic polymorphisms involved in folate metabolism and elevated plasma concentrations of homocysteine: maternal risk factors for Down syndrome in Brazil

The aim of the present study was to investigate the effect of polymorphisms C677T and A1298C in the methylenetetrahydrofolate reductase (MTHFR) gene, A2756G in methionine synthase reductase (MTR) gene and A80G in reduced folate carrier 1 (RFC1) gene, and plasma homocysteine (Hcy), on the maternal risk for Down syndrome (DS). Seventy-two DS mothers and 194 mothers who had no children with DS were evaluated. The investigation of the MTHFR C677T, MTR A2756G and RFC1 A80G polymorphisms was performed by polymerase chain reaction and enzyme digestion and the MTHFR A1298C polymorphism by allele-specific polymerase chain reaction. Hcy quantification was carried out by liquid chromatography-tandem mass spectrometry. The median number of polymorphic alleles for the four loci tested was greater in DS mothers compared to the control group, and the presence of three or more polymorphic alleles increased the risk for having a child with DS 1.74 times. Elevated maternal risk for DS was also observed when plasma Hcy concentration was higher than 4.99 micromol/L. In conclusion, the presence of three or more polymorphic alleles for MTHFR C677T, MTHFR A1298C, MTR A2756G, and RFC1 A80G, and plasma Hcy concentrations higher than 4.99 micromol/L are maternal risk factors for DS.

METHYLENETETRAHYDROFOLATE REDUCTASE AND REDUCED FOLATE CARRIER-1 GENOTYPES AND METHOTREXATE SERUM CONCENTRATIONS IN PATIENTS WITH RHEUMATOID ARTHRITIS

We investigated the genotypes of methylenetetrahydrofolate reductase (MTHFR) and reduced folate carrier-1 (RFC-1), and the serum concentrations of methotrexate (MTX) in 100 outpatients with rheumatoid arthritis (RA). Frequencies of MTHFR C677T and A1298C were similar to those reported in Japanese RA patients, while frequencies of RFC-1 G80A genotypes differed from those reported in RA patients in the United States. No correlations were found between these genotypes and serum MTX levels.

Methylenetetrahydrofolate-dehydrogenase 1958G→A polymorphism is a genetic determinant of NTD risk for Italian mothers

Neural Tube Defects (NTDs) have a well-established genetic basis, although specific genetic predisposing factors had not been identified until now. Genetic variants of enzymes involved with folate pathway might be expected to have impact on NTD risk. Given its key role in folate metabolism, the methylenetetra-hydrofolate dehydrogenase (MTHFD1) could represent an attractive candidate in NTD etiology. MTHFD1 is a trifunctional protein and mediates the interconversion of 5,10-MTHF; 5,10-methenylTHF; and 10-formylTHF. 10-formyl THF and 5,10methenylTHF are the donor cofactors for de novo purine and pyrimidine biosynthesis and, thus, the biosynthesis of DNA. Recently, a polymorphism, G1958A, in the MTHFD1 gene was suggested as maternal genetic risk factor for NTD in the Irish population. In this study, we examined the impact of the MTHFD1 G1958A polymorphism on NTD risk in the Italian population by a casecontrol study and family-based studies. The study population consisted of 95 unrelated Italian NTD children, 42 mothers and 40 fathers who were recruited from the Spina Bifida Center of the Gaslini Hospital, Genoa. A total of 145 healthy individuals were recruited from a blood donors accessible bank and used as control group. The presence of the MTHFD1 1958G→A, MTHFR (methylenetetrahydrofolate reductase) 1298A→C and RFC-1 (reduced folate carrier 1) 80A→G polymorphisms was investigated by PCR-RFLP methods. We found no increased risk for MTHFD1 mutant genotypes of the children and fathers. On the contrary, significant risk estimates resulted for the homozygous 1958AA genotype of the mothers (OR = 3.05; P = 0.046). This maternal effect was confirmed by transmission disequilibrium test (TDT) that showed no preferential transmission of 1958A allele to the affected children from informative parents. Since our previous study has shown that the MTHFR A1298C and RFC-1 A80G polymorphisms are genetic determinant of NTD risk for Italian mothers, potential gene-gene interactions were examined. We found a significant interaction between the MTHFD1 G1958A polimorphism and both MTHFR A1298C (4.46-fold increased risk) and RFC-1 A80G (9.14-fold increased risk) mutant alleles in the mothers. We conclude that a common genetic variant of MTHFD1 gene, the G1958A, is a maternal genetic risk factor for NTD. These findings highlight the importance of further considering maternal genotype when evaluating NTD susceptibility loci. from 48th Annual Meeting of the Society for Research into Hydrocephalus and Spina Bifida Dublin, Ireland, 23–26 June 2004 Published: 23 December 2004

Maternal periconceptional vitamin use, genetic variation of infant reduced folate carrier (A80G), and risk of spina bifida.

Women who consume folic acid in early pregnancy reduced their risks for delivering offspring with neural tube defects (NTDs). The underlying process by which folic acid facilitated this risk reduction is unknown. Investigating genetic variation that influences cellular absorption, transport, and metabolism of folate will help fill this data gap. We focused our studies on a candidate gene that is involved in folate transport, the reduced folate carrier 1 (RFC1). Using data from a California population-based case control interview study (1989-1991 birth cohorts), we investigated whether spina bifida risk was influenced by an interaction between a polymorphism of infant RFC1 at nucleotide 80 (A80G) and maternal periconceptional use of vitamins containing folic acid. Allelic variants of RFC1 were determined by genotyping 133 live-born spina bifida case infants and 188 control infants. The percentages of case infants with the A80/A80, G80/G80, and G80/A80 genotypes were 27.2%, 28.0%, and 44.7%, respectively. The percentages of control infants were similar: 26.1%, 29.3%, and 44.7%. Odds ratios of 1.0 (95% confidence interval 0.5-2.0) for the G80/G80 genotype and 1.1 (0.6-2.0) for the G80/A80 genotype were observed relative to the A80/A80 genotype. Among mothers who did not use vitamins, spina bifida risk was 2.4 (0.8-6.9) for infants with genotype G80/G80 compared to those with A80/A80 genotype. Among mothers who did use vitamins, the risk was 0.5 (0.1-3.1) for infants with the G80/G80 genotype. Although this study did not find an increased spina bifida risk for infants who were heterozygous or homozygous for RFC1 A80G, it did reveal modest evidence for a gene-nutrient interaction between infant homozygosity for the RFC1 G80/G80 genotype and maternal periconceptional intake of vitamins containing folic acid on the risk of spina bifida.