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Molecular genetic analysis of the gene encoding the trifunctional enzyme MTHFD (methylenetetrahydrofolate‐dehydrogenase, methenyltetrahydrofolate‐cyclohydrolase, formyltetrahydrofolate synthetase) in patients with neural tube defects
Author(s) -
Hol Frans A,
Put Nathalie MJ,
Geurds Monique PA,
Heil Sandra G,
Trijbels Frans JM,
Hamel Ben CJ,
Mariman Edwin CM,
Blom Henk J
Publication year - 1998
Publication title -
clinical genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.543
H-Index - 102
eISSN - 1399-0004
pISSN - 0009-9163
DOI - 10.1111/j.1399-0004.1998.tb02658.x
Subject(s) - methylenetetrahydrofolate reductase , thermolabile , genetics , biology , neural tube , spina bifida , single strand conformation polymorphism , neural tube defect , population , mutation , gene , genotype , medicine , biochemistry , enzyme , embryo , environmental health
It is now well recognized that periconceptional folic acid or folic acid containing multivitamin supplementation reduces the risk of neural tube defects (NTDs). Recently we were able to show that homozygosity for a thermolabile variant of the enzyme methylenetetrahydrofolate reductase is associated with an increased risk for spina bifida in patients recruited from the Dutch population. However, this genetic risk factor could not account for all folic acid preventable NTDs. In an attempt to identify additional folate related enzymes that contribute to NTD etiology we now studied the methylenetetrahydrofolate dehydrogenase gene on chromosome 14q24 which encodes a single protein with three catalytic properties important in the folate metabolism. The cDNA sequence of 38 familial and 79 sporadic patients was screened for the presence of mutations by single strand conformation polymorphism (SSCP) analysis followed by sequencing. Two amino acid substitutions were identified. The first one (R293H) was detected in a patient with familial spina bifida and not in 300 control individuals. The mutation was inherited from the unaffected maternal grandmother and was also present in two younger brothers of the index patient, one of them displaying spina bifida occulta and the other being unaffected. The second change turned out to be an amino acid polymorphism (R653Q) that was present in both patients and controls with similar frequencies. Our results so far provide no evidence for a major role of the methylenetetrahydrofolate‐dehydrogenase (MTHFD) gene in NTD etiology. However, the identification of a mutation in one family suggests that this gene can act as a risk factor for human NTD.