There are a number of reasons why a saliva sample may not meet our quality assurance standards, meaning that Helix is not able to sequence the sample. Some reasons may be resolved by collecting another sample. Other reasons may be due to some other underlying variation in a person’s health or DNA.
Here are some of the more common reasons why Helix may not be able to sequence a person’s DNA:
- All saliva samples contain some bacteria, this is normal. However, for a variety of reasons some samples may have too much bacteria, which can trigger the need to provide another sample.
- Similarly, if a sample has other contaminants, like food particles, the sample will not pass our standards, and this would also trigger the need to provide another sample.
- Less common is that some people have a condition that affects their ability to provide enough saliva for collection.
- Since the cells in the saliva sample that contain DNA are what we call “white blood cells”, someone who has had a condition or treatment, like recent chemotherapy, bone marrow transplant, or active diagnosis of a hematological cancer, that impacts their white blood cells may not be able to be sequenced.
- In other cases there may be an underlying variation in a person’s DNA, such as the number of chromosomes, that would cause a sample to fail our checkpoints. While most people with such a difference in the number of chromosomes are likely aware of their condition, some may not be.
It is important to understand that the Helix lab is not intended to identify or diagnose the reasons why a sample fails. If your sample does not pass our quality processes, we will let you know that it cannot be sequenced, but we will not be able to tell you the specific reason why.