Collaborative Stage

Note 1: This is a special molecular diagnostic test performed on tumor tissue to identify loss of genetic material normally found on the long arm of one of the patient's two copies of chromosome 18. A normal cell will contain two complete copies of each chromosome, one from each parent, and this normal state is termed heterozygous. Loss of heterozygosity (LOH) is an abnormal state reflecting damage to the chromosome.
Note 2: Other terms for loss of heterozygosity include gene deletion and allelic loss.

Code	Description
010	Test positive for loss of heterozygosity
020	Test negative for loss of heterozygosity
988	Not applicable: Information not collected for this case
997	Test ordered, results not in chart
998	Test not done (test was not ordered and was not performed)
999	Unknown or no information Not documented in patient record

CS Site-Specific Factor 10
18q Loss of Heterozygosity (LOH)