Test failure of the deletion/duplication, also known as Copy Number Variation (CNV), analysis occurs in a very small percentage of cases. The specific cause for CNV test failures is speculative and it is likely due to a variety of specific scenarios that have accumulated to affect the DNA quality/quantity in a manner that caused the failure. These factors may include more severe and/or metastatic disease. underlying hematological malignancy, age of sample, sample conditions, etc. Recent chemotherapy, or other treatments that may have decreased white blood cell counts and/or caused DNA damage, may also cause test failure. If the failure occurred with a blood or saliva sample, we recommend submitting a new, preferably blood, sample.
For more information about the prevalence of deletions and duplications, please review this article.