Which poses less risk of passing an inherited disorder, transplants of adult bone marrow or infant cord blood?

Answer: This is a toss-up. More and more diseases are now recognized to have a genetic basis. We have always known that some diseases are passed by inheritence. Now we also recognize that some genetic mutations confer a greater predisposition to disease. For example, the “Philadelphia chromosome (translocation)” is associated with a predisposition to developing leukemia at some point in life. Many of these inherited predispositions do not manifest until adulthood. Plus, if the donor has one of these predispositions, some of the drugs that transplant patients take could trigger a malignancy in the donor cells.

On the one hand, older donors are better because they have more medical history to rule out inherited mutations. On the other hand, older donors are worse because they are more likely to have an acquired mutation, from exposure to disease or chemicals, etc. At this time, it is not clear whether older or younger donors are better.

It is possible to test donor cells for inherited mutations, which would be present in every cell. But with hundreds of known mutations, only a limited number can be screened with a reasonable amount of blood.

References:

• McMilin, K., 4/1/2002 Transfusion vol.42(issue 4):495
• Fraser, CJ etal. 23 Aug 2005 Blood;  “First report of donor cell derived acute leukemia as a complication of umbilical Cord Blood transplantation”.