I am now a chimera!

That sounds very exciting, but what exactly does it mean?

Wikipedia describes a chimera from Greek mythology: ‘The Chimera was a monstrous fire-breathing female creature, composed of the parts of three animals: a lion, a serpent and a goat. Usually depicted as a lion, with the head of a goat arising from its back, and a tail that ended in a snakes’s head. The term chimera has also come to describe any mythical or fictional animal with parts taken from various animals.’

In genetic terms, Wikipedia puts it like this: ‘chimera is a single organism that is composed of two or more different populations of genetically distinct cells. Each population of cells keeps its own character and the resulting organism is a mixture of tissues. This condition is either inherited, or is acquired through the infusion of allogeneic hematopoietic cells during transplantation or transfusion.’

I quite like the idea of being a monstrous fire-breathing creature, but I think the genetic description is a little more relevant.

Apparently, on the inherited side, if non-identical twins exist at embryo stage and one dies, it is possible for the cells to be subsumed by the other twin, which would be born as a single baby with a mixture of tissues, and the parents or child being none the wiser.

From Wikipedia again: ‘In 1953 a human chimera was reported in the British Medical Journal. A woman was found to have blood containing two different blood types. Apparently this resulted from cells from her twin brother living in her body. More recently, a study found that such blood group chimerism is not rare. Another report of a human chimera was published in 1998, where a male human had some partially developed female organs due to chimerism. In 2002, a woman was denied public assistance when DNA evidence showed that she was not related to her children. After hearing of a human chimera in New England, it was eventually found that she too was a chimera and thus had two sets of DNA.

Obviously, for me it has been acquired through the transplant. I know very little about my donor, only that she is a 19 year old British woman. As I know that the Anthony Nolan do recruitment drives at universities, particularly among medical students, I imagine her to be a medical student. And as I am Jewish, and therefore from a different genetic background from the majority of Anglo-Saxon British people, I also imagine that she may be Jewish too, from an Eastern European ethnic background like myself. This is all conjecture on my part, but I found this, so it is quite likely:

From Ezer Mizion (an Israeli Health support organisation): ‘Chances for a match increase significantly if the patient and potential donor share the same ethnic background. Because Jews in the past lived in isolated communities, they are today more genetically related to each other than to non-Jews. There are over 10 million potential donors registered in the International Bone Marrow Registry (BMDW), but only a very small percentage are of Jewish descent.

Anthony Nolan operates a two year confidentiality period between patients and donors to ensure that no one feels under pressure. Initial contact has to come from the patient. I have been told that I could send a thank you card, with just my first name on it. After two years, if both parties wish, they can exchange contact details and make direct contact. Occasionally a transplant patient might choose to meet with their donor. I have no idea if I will want to retain/make contact, but I will definitely be sending a thank you card.

I had thought that my whole DNA would change and I’ve shared jokes with fellow transplant buddies that we could commit a crime prior to transplant and get away with it, as they wouldn’t be able to trace us. However, what I came to understand and has been confirmed by my consultant, is that only my ‘population of blood cells’ is from the donor, but the rest of me is still the original article. So my whole blood system is genetically distinct from the rest of my body. If a DNA swab was taken from inside my mouth, my skin, fingernails or hair, it would show up as a completely different person (original me!) to a DNA test taken from my blood (donor).

I find this science absolutely mind-blowing!

Every few weeks, they do a blood test for chimerism. This is to see how much of my blood/marrow/immune system is my original system and how much is of the donor. At present, it is 100% donor. The consultant said that this can change, which startled me. If it’s 100%, how can it change without some input? She explained that although they say 100%, it is probably 99.999999%, leaving room for a bit of my original blood to exist and potentially push back against the incoming cells. So they will continue to take chimerism tests for some time… possibly forever. I shall have to ask about that.

Of the people who need a stem cell or bone marrow transplant (people with leukaemia, lymphoma or myeloma), only 30% find a match within their families. The other 70% turn to the register to find them an unrelated donor. Sadly, they can only find a match for around half the people who need one, despite the fact that they don’t just check in the UK, but worldwide.

One of my myeloma buddies is in remission following her auto stem cell transplant, but she was advised that her chance of a long remission is poor due to a chromosome abnormality. For this reason, her consultant suggested a follow-up donor transplant, which after some deliberation she agreed to do. Sadly though, neither of her siblings was a match, nor could one be found on a bone marrow register.

Even though I am not yet ready to consider working, I am now feeling well enough to want to contribute in some way. I would like to do something meaningful within my abilities, so from my own experience and with my friend in mind, I have contacted the Anthony Nolan Trust to volunteer in helping to organise or participate in a recruitment event. They hold recruitment events at all sorts of venues around the country to recruit new potential donors, usually large organisations or meeting places. In fact they are holding an event this Friday at Nottingham Forest Of course I shall blog about it if and when it happens.

I am now a chimera and so far doing well with my donor stem cells, but others may not be able to find a match. Just think if it was someone in your family or a close friend…

So, I’d like to use this forum to encourage anyone reading this to consider doing something amazing that could save someone’s life, with no financial cost, but huge rewards…

The Anthony Nolan Trust recruits potential donors aged 16-30, as younger people make the most successful donors. The British Bone Marrow Registry however, will take donors aged 18-49. They are particularly keen to have donors from black and other ethnic minority groups. Even if you’re not eligible, you could encourage a young friend, son or daughter to consider registering. The initial test is simply a spit, but if you want to know more, the Anthony Nolan Trust have this helpful video that explains the whole process, with no gory bits:


If you don’t live in the UK, there will be an organisation in your country where you can find out more about being a donor. They seem to have slightly different age eligibilities. Here are a few:
USA: National Marrow Donor Program
Canada: Canadian Blood Services
The Netherlands: Nederlandse Stamceldonorbank
New Zealand: New Zealand Bone Marrow Donor Registry
Australia: Australian Bone Marrow Donor Registry
Israel: Ezer Mizion Bone Marrow Donor Registry

Do something amazing and help someone else
become a monstrous fire-breathing creature!