title: Analysis of the MTHFD1 promoter and risk of neural tube defects.
abstract: Genetic variants in MTHFD1 (5,10-methylenetetrahydrofolate dehydrogenase/5,10-methenyltetrahydrofolate cyclohydrolase/ 10-formyltetrahydrofolate synthetase), an important folate metabolic enzyme, are associated with a number of common diseases, including neural tube defects (NTDs). This study investigates the promoter of the human MTHFD1 gene in a bid to understand how this gene is controlled and regulated. Following a combination of in silico and molecular approaches, we report that MTHFD1 expression is controlled by a TATA-less, Initiator-less promoter and transcription is initiated at multiple start sites over a 126 bp region. We confirmed the presence of three database polymorphisms (dbSNP) by direct sequencing of the upstream region (rs1076991 C > T, rs8010584 G > A, rs4243628 G > T), with a fourth (dbSNP rs746488 A > T) not found to be polymorphic in our population and no novel polymorphisms identified. We demonstrate that a common SNP rs1076991 C > T within the window of transcriptional initiation exerts a significant effect on promoter activity in vitro. We investigated this SNP as a potential risk factor for NTDs in a large homogenous Irish population and determined that it is not an independent risk factor, but, it does increase both case (chi (2) = 11.06, P = 0.001) and maternal (chi (2) = 6.68, P = 0.01) risk when allele frequencies were analysed in combination with the previously identified disease-associated p.R653Q (c.1958 G > A; dbSNP rs2236225) polymorphism. These results provide the first insight into how MTHFD1 is regulated and further emphasise its importance during embryonic development.
authors.affiliation: Dublin City University, Ireland.
authors.forename: Nicola
authors.initials: N
authors.lastname: Carroll
authors.forename: Faith
authors.initials: F
authors.lastname: Pangilinan
authors.forename: Anne M
authors.initials: AM
authors.lastname: Molloy
authors.forename: James
authors.initials: J
authors.lastname: Troendle
authors.forename: James L
authors.initials: JL
authors.lastname: Mills
authors.forename: Peadar N
authors.initials: PN
authors.lastname: Kirke
authors.forename: Lawrence C
authors.initials: LC
authors.lastname: Brody
authors.forename: John M
authors.initials: JM
authors.lastname: Scott
authors.forename: Anne
authors.initials: A
authors.lastname: Parle-McDermott
mesh_terms: D000483:Alleles; D001483:Base Sequence; D016022:Case-Control Studies; D019295:Computational Biology; D017931:DNA Primers / Q000235:genetics; D005260:Female; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D007231:Infant, Newborn; D007494:Ireland; D008754:Methylenetetrahydrofolate Dehydrogenase (NADP) / Q000235:genetics*; D008969:Molecular Sequence Data; D009436:Neural Tube Defects / Q000201:enzymology* / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D011247:Pregnancy; D011401:Promoter Regions, Genetic; D012307:Risk Factors; D024363:Transcription Initiation Site
chemical_list: D017931:DNA Primers; D008754:Methylenetetrahydrofolate Dehydrogenase (NADP)