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 19. 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 LOH include gene deletion and allelic loss.
Note 3: For brain tumors, tests for LOH of chromosomes 1p and 19q may be performed at the same time and reported on a single report. See also CS Site-Specific Factor 5.

Code	Description
010	Test positive for loss of heterozygosity (LOH)
020	Test negative for LOH
888	OBSOLETE DATA CONVERTED V0200 See code 988 Not applicable for this site
988	Not applicable: Information not collected for this case (May include cases converted from code 888 used in CSv1 for "Not applicable" or when the item was not collected. If this item is required to derive T, N, M, or any stage, use of code 988 may result in an error.)
997	Test ordered, results not in chart
998	No histologic examination of primary site Test not done (test not ordered and not performed)
999	Unknown or no information Not documented in patient record

CS Site-Specific Factor 6
Chromosome 19q: Loss of Heterozygosity (LOH)