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How can one lab report mutated and one lab report unmutated? Should I consider repeat testing?

Ask the Lab Scientist Question:

I’m a newly diagnosed patient and my questions relates to disparities between lab results. The tests were done by ordered by two oncologists I’ve seen and were performed by two different labs.

The first lab (Cairo, White Plains) results show mutated IGHV (6.4% mutation rate) while the second (MSKCC) show bi-allelic/biclonal rearrangement with one productive and one unproductive but both unmutated (0% mutation frequency on both).

In addition, the Cairo lab reports deletion on 11q22.3 with ATM Deletion of 6.0% while the MSK lab reports CN-LOH in segment 11q13.2-q25, including the ATM gene.

  1. How can one lab report unmutated and one lab report unmutated? Should I consider repeat testing?
  2. Can you explain the 11q22 vs 11q13 difference?

Answer: By all means, get tested again. Afterall, you need to have a clear sense of what is going on before you and your physician decide how to proceed, Talk to him/her about that. It may be that different primers might have been used or there was some irregularity in the transport or processing of your specimen.

The test showing the 11q13.2-q25 reflect a loss of a large segment of chromosome 11 between loci 13.2 and 25, while the test showing 11q22.3 apparently could have been focused specifically on that portion of the chromosome. When the loss of heterozygosity involves the normal allele, it creates a cell that is more likely to show malignant growth if the altered gene is a tumor suppressor gene, also called LOH.