As many of us have mixed race kids I thought this would be of interest.

Skynews has a story on problems finding a matching donor for a mixed Thai/Chinese/Italian girl diagnosed with leukaemia.

http://news.sky.com/story/1628051/bale-and-rowling-back-womans-donor-appeal

None of the 26 million people on bone marrow registers around the world are a match for Lara, who is of Thai and Italian heritage.

Those with caucasian heritage have a 60% chance of finding a suitable donor but those of mixed-ethnicity only have a 20% chance.

That is partly because of a lack of mixed-race people on international registers but also because it is less likely that a willing donor shares the specific combination of a mixed-race patient's ethnicities.

Lara said: "It was my family that looked into it really and found out that only 3% on the worldwide registers are of mixed-race origin which makes it much harder to find a match.

I never realized that race would be a factor in marrow transplants. Presumably siblings from the same parents would be a possibility.

Compared to organ transplants, bone marrow donations need to be even more genetically similar to their recipients. Though there are exceptions, the vast majority of successful matches take place between donors and patients of the same ethnic background. Since all the immune system's cells come from bone marrow, a transplant essentially introduces a new immune system to a person. Without genetic similarity between the donor and the patient, the new white blood cells will attack the host body. In an organ transplant, the body can reject the organ, but with marrow, the new immune system can reject the whole body.