Chromosome 9 inversion

Chromosomes are the structures found in every cell of the body that contain our DNA, the instructions that tell our body what to do. Humans have 23 pairs of chromosomes, which means that each human cell contains 46 chromosomes. Each chromosome has a p and q arm; p is the short arm and q is the long arm. The p arm is always on the top and the q arm is on the bottom.

An inversion occurs when there are two breaks in one chromosome. The segment between the breakpoints flips around and reinserts back into the chromosome. Genetic material may of may not be lost as a result of the chromosome breaks. If both breaks occur in the same arm of the chromosome, this is called a paracentric inversion. If one break occurs in the short arm and the other in the long arm of the chromosome, then this is called a pericentric inversion.

 Chromosome 9 inversion is one of the most common structural balanced chromosomal variants, with an estimated incidence of about 3.5 percent. It remains unclear, however, if these rearrangements have clinical significance. In some cases, it has been associated with congenital anomalies, growth retardation, infertility, recurrent pregnancy loss, and cancer.