21. As with an amniocentesis, analysis can detect neural tube defects and genetic disorders. 22. There are genetic as well as dietary factors that cause neural tube defects. 23. Neural tube defects are among the most common and most destructive birth defects.24. The neural tube gives rise to both brain and spinal cord. 25. Hyperhomoscyteinemia has also been associated with early pregnancy loss and with neural tube defects. 26. These are the most common forms of what are known as neural tube defects. 27. Both originate from the embryonic neural tube and are located between the two siphons. 28. In spina bifida, the neural tube fails to close properly at the lower end. 29. Higher-than-normal levels are associated with neural tube defects, and lower-than-normal levels with Down syndrome. 30. In the central nervous system, glia develop from the ventricular zone of the neural tube .
