Does prenatal screening for 5,10-methylenetetrahydrofolate reductase (MTHFR) mutations in high-risk neural tube defect pregnancies make sense?
Despite the fact that neural tube defects (NTDs) are the most common congenital malformations of the central nervous system, investigators have yet to identify responsible gene(s). Research efforts have been productive in the identification of environmental factors, such as periconceptional folic acid supplementation, that modulate risk for the development of NTDs. Studies of the folic acid biosynthetic pathway led to the discovery of an association between elevated levels of homocysteine and NTD risk. Researchers subsequently identified single nucleotide polymorphisms in the gene coding for the enzyme 5,10-methylenetetrahydrofolate reductase (MTHFR). Association studies suggested it was a potential risk factor for NTDs, because the thermolabile form of the enzyme led to elevated homocysteine concentrations when folic acid intake is low. Numerous studies analyzing MTHFR variants have resulted in positive associations with increased NTD risk only in certain populations, suggesting that these variants are not large contributors to the etiology of NTDs. With our limited understanding of the genes involved in regulating NTD susceptibility, the paucity of data on how folic acid protects the developing embryo, as well as the observed decrease in birth prevalence of NTDs following folic acid supplementation and food fortification, it makes little sense for prospective parents to be tested for MTHFR variants, or for variants of other known folate pathway genes.
Finnell
Richard H
RH
Institute of Biosciences and Technology, Texas A&M University System Health Science Center, Houston, TX 77030, USA. rfinnell@ibt.tamu.edu
Shaw
Gary M
GM
Lammer
Edward J
EJ
Volcik
Kelly A
KA
D000818:Animals; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis* / Q000201:enzymology / Q000235:genetics; D005492:Folic Acid / Q000378:metabolism; D020022:Genetic Predisposition to Disease; D005820:Genetic Testing; D006710:Homocysteine / Q000378:metabolism; D006801:Humans; D015201:Meta-Analysis as Topic; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D051379:Mice; D018345:Mice, Knockout; D009154:Mutation; D009436:Neural Tube Defects / Q000175:diagnosis* / Q000201:enzymology / Q000235:genetics; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000235:genetics*; D011110:Polymorphism, Genetic; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000009:adverse effects
D006710:Homocysteine; D005492:Folic Acid; D000587:Oxidoreductases Acting on CH-NH Group Donors; D042965:Methylenetetrahydrofolate Reductase (NADPH2)