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Neural tube defects (NTDs) are a group of birth defects in which an opening in the spine or cranium remains from early in human development. In the third week of pregnancy called gastrulation , specialized cells on the dorsal side of the embryo begin to change shape and form the neural tube .
It is the process of formation of a flat neural plate which then convolutes to form the hollow neural tube. [8] It is considered to be one of the main targets of developmental toxicity and defects in neurulation is a common consequence of toxicant exposure and results in large proportion of human defects. [9]
Before folic acid fortification, about 4,100 pregnancies were affected by a neural tube defect each year in the United States. The Centers for Disease Control and Prevention reported in 2015 that since the addition of folic acid in grain-based foods as mandated by the FDA, the rate of neural tube defects dropped by 35%. This translates to an ...
Women who have already had a baby with spina bifida or other type of neural tube defect, or are taking anticonvulsant medication, should take a higher dose of 4–5 mg/day. [69] However, the daily requirement of folate and the recommended folate blood levels to prevent neural tube defects are not well established. [59]
Anencephaly is the absence of a major portion of the brain, skull, and scalp that occurs during embryonic development. [1] It is a cephalic disorder that results from a neural tube defect that occurs when the rostral (head) end of the neural tube fails to close, usually between the 23rd and 26th day following conception. [2]
For a short time, the neural tube is open both cranially and caudally. These openings, called neuropores, close during the fourth week in humans. Improper closure of the neuropores can result in neural tube defects such as anencephaly or spina bifida. The dorsal part of the neural tube contains the alar plate, which is associated primarily with ...
For example, a lack of folic acid, a B vitamin, in the diet of a mother can cause cellular neural tube deformities that result in spina bifida. Congenital disorders such as a neural tube deformity can be prevented by 72% if the mother consumes 4 mg of folic acid before the conception and after twelve weeks of pregnancy. [70]
The most common congenital diseases are heart defects, Down syndrome, and neural tube defects. Trisomy 21 is the most common type of Down Syndrome. About 95% of infants born with Down Syndrome have this disorder and it consists of 3 separate copies of chromosomes.