The Geneticist and Myelodysplasia
The geneticist at Children's Healthcare of Atlanta is a specialist who studies the genes we inherit from our parents and how those genes affect our development. He can explain how myelodysplasia develops before birth. Through family histories and other means, he can also inform you of the risks and other factors involved in planning additional children. Because the field of genetics is advancing every day, the geneticist keeps up with recent research into the causes and prevention of myelodysplasia and other conditions.
Below are answers to some of the most common questions that parents ask the geneticist at Children's.
How does myelodysplasia develop?
Around the third week of pregnancy, a line of cells appears on the back of the embryo (the earliest development of the baby). These cells are called the neural plate. The neural plate will become the brain and the spinal cord. In about 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 overlying tissue. This tissue will become the backbone, muscle, fat and skin. A neural tube defect (NTD), such as myelodysplasia, occurs when the neural tube or its overlying tissue fails to develop properly.
Myelomeningocele is one type of NTD. In a child born with myelomeningocele, 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.
What causes myelodysplasia? Can it be prevented?
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 occurring again in affected families. It also appears to be effective in reducing the occurrence in the general population. Folic acid is a B-vitamin found naturally in green vegetables, fresh fruit and liver. It must be taken before conception to be effective in the early weeks of pregnancy. (Conception is the very earliest stage of pregnancy.)
Medical care before and during pregnancy is important. The dose of folic acid should be discussed with an obstetrician (OB), 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 also medical 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 and/or ultrasound examination of the fetus. These tests are recommended, since NTDs are not completely prevented by taking folic acid.
What are the chances that it will re-occur?
If you have a child with myelodysplasia, the chance of having another child with myelodysplasia is approximately three out of 100 (3 precent). If two children of the same parents are affected, the risk increases to about one out of 100 (10 precent) for a third child.
How can we plan for another child?
You may have concerns if you are considering having another child. If so, it is recommended that you have a consultation with a geneticist. A geneticist can give you current information about incidence and prevention. Research into the cause and prevention of myelodysplasia is ongoing. One leading research center is the Centers for Disease Control and Prevention (CDC) in Atlanta.