Myelodysplasia is one type of neural tube defect (NTD). In a child born with myelodysplasia, there is an open defect on the back. The neural plate fails to become rounded and the backbone, muscles and skin fail to take their proper place over the spinal cord.

Around the third week of pregnancy, a line of cells, called the neuro plate, appear on the back of the embryo. The neural plate will become the brain and the spinal cord. Around the fourth week of pregnancy, the neural plate changes shape. It becomes rounded into a tube called the neural tube. As it changes from a flat to a rounded shape, the neural tube is covered with tissue. This tissue will become the backbone, muscle, fat and skin. A NTD, such as myelodysplasia, occurs when the neural tube or its overlying tissue doesn’t develop properly.

Causes of myelodysplasia

Myelodysplasia is influenced by genetics. Although it can run in families—it occurs most frequently in those of Welsh or Irish descent—there is not one single gene that causes it. It is now thought to be caused by the action of several genes, along with the influence of some external factors.

No single environmental cause has been linked to NTDs, but research shows that folic acid can reduce the chance of NTDs. Folic acid must be taken before conception to be effective in the early weeks of pregnancy. Medical care before and during pregnancy is important. The dose of folic acid should be discussed with an obstetrician, since a higher dose is recommended for women who have had a baby with an NTD than for women who have never had an affected child.

There are tests to determine whether or not an unborn child is affected. These include tests on the mother's blood, tests on amniotic fluid from around the fetus or ultrasound of the fetus. These tests are recommended, since NTDs are not completely prevented by taking folic acid.

Chances of myelodysplasia occurring in another pregnancy

If you have a child with myelodysplasia, the chance of having another child with myelodysplasia is approximately three percent if two children of the same parents are affected, the risk increases to about 10 percent for a third child.

Planning for another child

You may have concerns if you are considering having another child. Doctors recommended that you have a consultation with a geneticist, who can give you specific information about risk and prevention. Research into the cause and prevention of myelodysplasia is ongoing.