Chromosome 9 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome, as they normally do with all chromosomes.
Chromosome 9 spans about 145 million base pairs of nucleic acids (the building blocks of DNA) and represents between 4 and 4.5 percent of the total DNA in cells. Deletions of part or all of chromosome 9 are commonly found in bladder cancers. These chromosomal changes are seen only in cancer cells and typically occur early in tumor formation. Researchers believe that several genes that play a role in bladder cancer may be located on chromosome 9. They suspect that these genes may be tumor suppressors, which means they normally help prevent cells from growing and dividing in an uncontrolled way.