Umbilical cord blood donation allows a type of stem cell transplant. This is my third post specifically about stem cell transplants and ancestry testing and it’s the first that focuses specifically on umbilical cord blood. You can read the first two about a case of bone marrow transplantation affecting an ancestry test result and how to try to go about DNA testing if you have already received a stem cell donation:
I am adding to the series because of this recent story published in the Chicago Tribune. DNA from a donated sample of umbilical cord blood 20 years ago led to ancestry testing connecting the recipient of the donation to the family whose baby’s cells were donated. Since first posting this blog post, Sarah Zhang who writes on the topic of DNA for the Atlantic also wrote about the story.
The short version for those who are unable to read it (I hear the site is blocked for Europeans) is this:
Two decades ago, a mother who had just given birth agreed to donate her newborn’s cord blood to a public bank; she promptly forgot about this. She never told her son his stem cells (via the umbilical cord blood) were donated. A stranger going through cancer treatment received the donated stem cells and lived (which is undeniably the best part of the story).
Fast forward to present day, the cancer survivor ordered a DNA test for ancestry and family finding purposes, not expecting that the cord blood donation those years ago would have an impact. The results came back matching her to a strange family; someone else showed up as a close match, either her mother or daughter. They messaged back and forth and figured out they’re a DNA match because one of them is the mother to the baby whose umbilical cord blood donation saved the life of the other. The DNA from that umbilical blood sample is now affecting who the cancer survivor matches by DNA.
This would be 100% a feel-good story if the implications of it were not so wide-reaching and concerning.
A little more background about umbilical cord donation…
At some hospitals, programs are in place to allow the umbilical cord blood from a baby’s afterbirth to be donated and used in the medical treatment of other people. The other options are to store the sample away for one’s own family’s use (privately, for a fee) or discard it as medical waste.
Within umbilical cord blood is a high concentration of a type of universal body cell (stem cell) that has the amazing ability to become almost any other type of cell needed. We all have stem cells throughout our entire lives, but the younger we are the more stem cells we have. Stem cells are important because they help our bodies bounce back from injury and the effects of aging. This is why umbilical cord blood is a golden opportunity to preserve the miracle of stem cells.
Donated stem cells graft themselves into the bone marrow of the person who is ill (typically after a course of chemotherapy is given) and from that point on, continue to grow and reproduce indefinitely. The rest of the person’s body cells remain the same, and contain the original DNA they were born with. But blood cells (white blood cells, to be specific, which are produced in the bone marrow) make their way into the saliva of the person, thus are transported along with other body cells (specifically epithelial cheek cells) when that person spits in a tube for a DNA test.
Many parents have opted to donate to a public bank rather than discarding it, if they don’t have the financial means or interest in privately banking it. After consenting, many parents forget all about it, which is understandable given how many decisions are made around the delivery of a child followed by the all-consuming care of infants after that. Parents may easily forget that they chose to donate their child’s umbilical cord blood and even if they remember at some point, they might not pass that important detail along to their child.
This means there are many people who have cells with their DNA living on inside the body of someone else where it is undetectable until DNA testing is done. We’ve known about bone marrow transplants (in which adults consent for their own stem cells to be shared with another person), but this Chicago Tribune story seems to be the first that indicates that cord blood donations can also have the same effects on DNA obtained from a saliva sample, like that which is tested by consumer genomics companies.
If the world were entirely benign, and if ancestry testing did not exist, this wouldn’t be a story. Here are a few reasons this story reveals we have new challenges to get ahead of.
Imagine your parent donated your stem cells:
If a recipient of your donated stem cells has a DNA test, YOUR results rather than result based on their inborn DNA might come back. The stranger will now match your family members. If you do not figure out the reason they are matching is because the DNA from your cord blood stem cells are inside their body, this might look like you’ve discovered a newfound family member, or that you have uncovered a family secret (sperm donation, infidelity, etc.).
Now imagine your DNA shows up at a crime scene and genetic genealogists working for law enforcement track the DNA back to your family…and say you happen to live in proximity to where the crime was committed or where the recipient of your anonymous cord blood donation also lives. Did you commit a crime or did they? What if you do not even know the other person (who has your DNA in their bone marrow) exists? U.S. law says a new DNA sample can be collected on you without your consent (from a discarded coffee cup in the trash at a fast food restaurant, for example) if you’re a criminal suspect. How will you be able to argue back against the DNA evidence, especially if you are not aware of another explanation (such as your cord blood was donated)?
There is no doubt that many people are alive today because of the miracle of stem cell donation, from cord blood samples and bone marrow. I have an uncle who had years added to his life after his leukemia diagnosis because a sibling was a match. I understand why this story was published by the Chicago Tribune as a happy and exciting story.
But ancestry testing has turned the world upside-down.
Everyone needs to know where their DNA came from and where it has gone.
Call me overly concerned about consent if you want. That is the Genetic Counselor in me. But it doesn’t take any special degree or title to know that everyone has a right to know what has been done with their own DNA and from whom they originate. This includes openness and honesty with children if they were conceived using egg, sperm, or zygote donation. Adopted persons and NPEs (children conceived from relationships other than what they believe as their true parentage) need support to learn their genetic identity.
And now, it seems, who has had their umbilical cord blood donated anonymously matters as well.