Neural tube defect

Neural tube defect
Illustration of a child with spina bifida, the most common NTD
Specialty	Medical genetics

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. When the neural tube does not close completely, an NTD develops.

Specific types include: spina bifida which affects the spine, anencephaly which results in little to no brain, encephalocele which affects the skull, and iniencephaly which results in severe neck problems.^[1]

NTDs are one of the most common birth defects, affecting over 300,000 births each year worldwide.^[2] For example, spina bifida affects approximately 1,500 births annually in the United States, or about 3.5 in every 10,000 (0.035% of US births),^[1][3] which has decreased from around 5 per 10,000 (0.05% of US births) since folate fortification of grain products was started.^[3] The number of deaths in the US each year due to neural tube defects also declined from 1,200 before folate fortification was started to 840.^[4]