How to test your DNA (even if you've had a stem cell transplant)

How to test your DNA (even if you've had a stem cell transplant)

What happens to DNA when someone has a stem cell transplant?

Some people have had a stem cell transplant using their own stem cells. This type of transplant does not have any impact on DNA and DNA test results. Organ transplants also do not appear to impact DNA results, even though the organ has come from a different person whose DNA differs from you.

Those who have had stem cell transplants in which they’ve received a stem cell donation from another person run into challenges when having a DNA test on blood or saliva. After transplant, the white blood cells circulating through the body contain the DNA of the stem cell donor because the blood-producing cells of the bone marrow have been replaced by the donor’s. Red blood cells are essentially sacks of hemoglobin and don’t contain DNA, so only white blood cells are the issue.

GEDmatch & the Are Your Parents Related tool: What it means if you see a lot of blue

GEDmatch is a free website with tools that enable genealogists to use DNA and family trees to search for relatives. It has been in the news lately because it has recently been used to to identify criminal suspects. Tracing individuals based on their relatives DNA and family trees are only part of what GEDmatch allows DNA researchers to do. Other tools are available on GEDmatch, including one called "Are Your Parents Related?" (AYPR, for short). 

GEDmatch, raw data, and solving violent crimes with genetic genealogy

Kendra Nichols from abc27 News interviewed me about DNA testing, and we chatted a bit about the fine print you agree to when you submit a DNA sample to a consumer testing company.

Although it isn't named in the short news segment, a voluntary site created for genealogists called GEDmatch is the site law enforcement and others are using to solve crimes. Solving crimes has included finding suspected perpetrators and identifying victims (in other words, re-identifying deceased persons whose bodies were found and that police were previously unable to identify; these are referred to as John and Jane Doe cases).

DNA security: my thoughts in the wake of the Golden State Killer case development

The use of the genealogical DNA website called GEDmatch to solve a long history of crimes perpetrated by the Golden State Killer has a lot of people wondering, “Should I be concerned about the privacy and security of my DNA?” There is nuance to this question. One person who asks it might be asking whether a company might give away their information without permission. Another one might be more concerned about whether someone with ulterior motives could 'hack' the system at a company (or at an independent DNA sharing site) and take data not approved by customers or users.

Without getting into the weeds too deeply, my opinion on this in a nutshell is this:

Think of DNA security the way you think about credit cards. 

Some people opt out of using credit cards because they know of theft; it’s happened to them or someone they know. Or they are generally worried about it even if they've not yet been affected personally. Other people may weigh the risks of private information being stolen if they use a credit card (or other digital payment system like PayPal), but then decide the ease of using them is worth the risk. It has become culturally normal to use credit cards and online payment systems, and the risks are understood and accepted. 

It almost seems as if no one expects perfection in credit card security. So it is becoming for DNA testing as well.

There will always be a spectrum of how much risk people are willing to take, and that’s ok. We all are different and have had different experiences that attune us to what ought to be cause for worry. What concerns us is not the same as what concerns others. 

The reports of genetic information being 'stolen by bad guys' are non-existent at this point; however, law enforcement has tried to get genomics companies to turn over information, mostly unsuccessfully. The Golden State Killer case recently in the news was a situation in which the absence of laws and regulations around publicly-shared information about DNA matches meant law enforcement was free to use it in a way that helped them solve their case. This wasn't stolen information, per se, but few people who had uploaded their computerized DNA information to GEDmatch seem to have anticipated this use. Some are okay with it, some are not (and have reached out to request their data be deleted).

Are you okay with the use of DNA from family members by law enforcement to solve cases of murder and rape? There isn’t a right answer to this one, but we should still be asking it and discussing it.

What about DNA being held by private companies, like 23andMe and In comparison to third-party DNA sharing sites where 'user beware' is the expectation, genomics companies have it in their interest to keep your information as secure as they can -- their reputation hinges on it, in a way.

So they are trying, but in spite of all efforts including the employment of folks with titles like "Chief Security Officer", it might be possible in the future that their security fails. Or that they slip in some language into the terms of service agreement that gives them more freedom to use and share your DNA information than you fully understand.

So bottom line, do I think you should take a DNA test? 

You probably aren't surprised that my answer is the decision falls right back on you.

If you’re ok with the chance of your DNA being used in unique ways or in going farther than you imagined it would in order to answer other people’s questions, take the test. If not, testing might not be right for you. 


Interested in reading more about the Golden State Killer case and how genetic genealogy was involved? This blog post by genetic genealogy blogger Debbie Kennett compiles many relevant articles related to the case.

Want help in understanding the terms of service before you send in your DNA sample or share your computerized DNA file with a third-party website? I'm a licensed and certified genetic counselor, and "seek informed consent" is one of my mantras. Schedule a one-time session with me, and I'll be happy to help you go through the terms you're being asked to agree to.

DNA Testing After a Stem Cell Transplant: a Fascinating Case

When you have an allogeneic bone marrow or stem cell transplant, the blood-producing cells in your bone marrow are killed off by radiation or chemotherapy and then replaced with functioning cells from another person. The technical term for this process is allogeneic hematopoietic cell transplantation

"High ROH" in your DNA - what is it and what can you do next?

Sometimes in the course of testing DNA, we get a surprise with the results. A surprise we have found happening more often the more we test is the DNA feature of high levels of ROH, or "runs of homozygosity." This feature often reveals a recent close genetic relationship between the parents of the person tested. 

If you have used a tool to analyze your DNA like the "Are Your Parents Related?" tool on GEDmatch (or David Pike's tools), and the results show the probability of your parents being closely related is high, the "High ROH" information sheet is for you. Click the link below to see it. 

Sometimes only a small region of DNA (or only one chromosome) shows a high ROH result. Different biological reasons explain these findings. Reach out to Watershed DNA if you need more support.

If you could use support in the form of the story of someone else who discovered ROH, you can follow this link to John’s story about his ROH discovery here.

**This post was updated 12/29/18 to include the link to the updated version of John’s story and shared with his permission.