In this condition there is inversion of a segment of one of the chromosomes that results in neither gain nor loss of
genetic material. This means that a person carrying an inversion is almost always
healthy. There is a relatively small risk, however, of having a child with an unbalanced
chromosome arrangement where there may be gains or losses of
A significant number of such pregnancies abort spontaneously at the beginning of
the pregnancy. An inversion can be detected during pregnancy by amniocentesis or chorionic villus sampling.
There are a number of very common inversions in the population, especially in chromosomes
2, 9 and 17, which in most cases are transmitted unchanged from parent to child.
In these cases there is usually no reason to examine the fetus, because the likelihood
that there will be a problem in the fetus is very small.