amniocentesis

Question

Hello, I had a son diagnosed with CF (homozygot delta F508). If we decide to have another child, will the amniocentesis test all the chromosomes or just the chromosome responsible for CF. Is it possible that we, the parents, might have other mutations besides deltaF508? How many mutations exist in CF? Is the deltaF508 the most severe? At what gestational age do we have to take this test and how long does it take before we know the result?

Answer

Hello, in case of another pregnancy, there are 25% chances that your future baby is perfectly healty and 50% chances to be just carrier of one pathologic mutation; of course he could also be sick (25% risk). Amniocentesis can establish the child’s genotype. This is usually performed at 13-15 weeks of gestation; some of the couples that have had babies with CF had the genetic test, and in 5 years only one couple from our patients had a genetic test positive for CF. The result of the test is available in the same amount of time as any genetic test, depending on every laboratory. In your case, you are only carriers for this mutation; if you would have one more, you would be sick. A sick person has genotype compound for two mutations, each one inherited from each parent. Until now there are more than 1800 CF specific mutations, deltaF508 beeing the most frequent of all; it is a 2nd class mutation, considered to be severe. Best regards,
Prof. Pop

22.03.2012