18q Loss of Heterozygosity (LOH)


To determine the presence of loss of heterozygosity (LOH) of the long arm of chromosome 18 (18q) that results in inactivation of tumor suppressor genes and is often associated with hereditary non-polyposis colon cancer (HNPCC). The presence of 18q LOH has been associated with adverse outcomes in patients with Stage II and Stage III colon cancers and in conjunction with other molecular tests, is able to assist in the diagnosis and prognosis of patients with HNPCC.


Detection of LOH is performed using multiplex PCR products and capillary electrophoresis. A panel of five fluorescent-labeled markers, D18S55, D18S58, D18S61, D18S64, and D18S69 is used in assessing the loss of heterozygosity of 18q. An additional marker D18S1147F is available for additional clarification of cases with a number of non-informative alleles.

Test Parameters

Both samples from tumor and normal (uninvolved) samples must be analyzed to assess for loss of heterozygosity.

Turnaround Time

Seven to 10 working days

Sample Requirements

  • Sections of microdissected, paraffin-embedded tissue fixed on five to six slides (with clear indication of tumor and normal areas)

  • Frozen tissue samples (separated into normal and tumor)

Please provide a copy of the corresponding pathology report.

CPT Codes


Additional charges will apply for tissue extraction.

The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.