Neural tube defect

A neural tube defect will occur in human embryos if there is an interference with the closure of the neural tube that occurs around the 28th day after fertilization. The incidence of neural tube defects is 2.6 in 1,000 worldwide.^{[citation needed]}

Causes

Pregnant women taking medication for epilepsy have a higher chance of having a child with a neural tube defect. Research has shown that women with folic acid deficiencies also have a higher chance of having a child with a neural tube defect, but this is only one factor. Taking folic acid does not completely negate the risk of neural tube problems, but it does significantly reduce the risk. Folic acid deficiency leads to hyper-homocysteinemia,which in turn results in neural tube defects.

Other potential causes can include folate antimetabolites (such as methotrexate), maternal diabetes, maternal obesity, mycotoxins in contaminated corn meal, arsenic, and hyperthermia in early development^[1].

Prevention

In Canada, mandatory fortification of selected foods with folic acid has been shown to reduce the incidence of neural tube defects by 46%^[2].

Women who are or could become pregnant are advised to take daily supplements of folic acid, unless their dietary intake of this nutrient during pregnancy is already high. Lack of vitamin K can also cause an increase of neural tube defects^{[citation needed]}.

Detection

Neural tube defects may be detected by a variety of methods, including some prenatal screening tests and medical imaging. Often, these defects are apparent at birth, but occult defects may be not diagnosed until much later in life. Elevated levels of Alpha-fetoprotein (AFP) are seen in maternal blood or in the amniotic fluid when neural tube defects occur. Non pregnant women in child bearing age should consume about 400 mcg of folic acid daily. It is recommended that pregnant women consume 800 mcg.

Types of neural tube defects

• Anterior
  • Anencephaly
  • Encephalocele
• Posterior
  • Spina bifida including myelomeningocele and others

References

1. ^ eMedicine url=http://www.emedicine.com/NEURO/topic244.htm
2. ^ De Wals P, Tairou F, Van Allen MI, et al. (2007). "Reduction in neural-tube defects after folic acid fortification in Canada". N Engl J Med 357 (2): 135–142. doi:10.1056/NEJMoa067103. PMID 17625125. http://content.nejm.org/cgi/content/short/357/2/135?query=TOC. 

See also

• Neurulation

External links

• MedlinePlus

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