We often focus on the pharmacological aspects of personalized medicine, but understanding a patient's complete genetics can yield benefits beyond the pill bottle.

Graft-Versus-Host Disease (GVHD) is a painful, sometimes serious complication that occurs after a bone marrow or stem cell transplant. These kinds of transplants are often performed in patients with immune systems damaged by leukemia, myeloma, or certain immunodeficiency syndromes. Ideally the transplant will produce new immune cells, however differences in cellular proteins between the host and transplanted cells sometimes cause the new immune system to regard host's cells not as a healthy body, but as foreign invaders. The new immune cells attack the host's tissues and organs, causing cramps, fatigue, and in some cases organ damage.

Because GVHD is caused by differences in the cellular proteins, transplant doctors carefuly try to match donor and host. The safest transplants use a patient's own bone marrow (which is called an autologous transplant) but this isn't always feasable.  Doctor's then usually ask related individuals to donate, since they naturally share most of the protein-producing genes, or try to match patients based on genetic profiles.  The more closely a doctor can match patient and host, the less likely GVHD.

A new study from the Fred Hutchinson Cancer Research Center may make this matching process even more precise. The Fred Hutchinson is already famous for pioneering bone marrow transplants in the 1970's. This new study identifies two single-nucleotide polymorphisms (SNPs) in the MHC cellular proteins that can be used to predict GVHD likelihood. These SNPs, mutations to a single 'letter' of DNA, had been previously unexamined, but it seems that patients with identical forms of these polymorphisms were much less likely to develop GVHD.

It's hoped that adding these SNPs, and their associated genes, to a donor search could reduce the prevalance of GVHD and help improve the overall quality of life for transplant patients.