I am 29 and getting ready to start planning for a family. My sister would have been 42 today, but she was stillborn with spina bifida. My mother's father had scoliosis and my mother's brother had a daughter that had steel rod in her back. Is this genetic and will I need counseling, or is this something I can help prevent by taking folic acid?
The common group of birth defects called neural tube defects includes spina bifida. The vast majority of these defects arise as a consequence of the interaction between susceptibility genes and some environmental trigger. Which particular genes make a couple susceptible to having an affected child are not yet fully recognized.
At least one outside trigger is now well known: Folic acid (vitamin B complex) has proved to be an extremely important factor. We now know that women who take folic acid supplements or multivitamins containing at least 400 mcg of folic acid daily, while planning pregnancy and continuing through the first six weeks, avoid some 70 percent of cases with spina bifida. I was pleased to read that you are probably taking folic acid already and am amazed how many women appear not to know this critical information.
Given your history, your personal risk approximates one percent or less for having a child with a neural tube defect, like spina bifida. The minimum recommendations for you would be to take 400 mcg of folic acid daily while planning pregnancy and through at least the first six weeks of pregnancy, have the routine maternal serum quadruple screening test (for spina bifida and Down syndrome) at 16 weeks, and have a high-resolution targeted ultrasound study between 16 and 18 weeks of pregnancy.
As long as you can be assured that high quality ultrasound studies are available to you, amniocentesis may not be necessary, but they remain a consideration and an option you have.
Seeing a clinical geneticist for genetic counseling may prove of additional help to you. The scoliosis issue is entirely separate and due to either a single gene or multiple genes unrelated to the spina bifida history.