Rare Blood Donor

Your Red Blood Cell Type is Inherited

Genes that we inherit from our parents determine which of the many subtypes (tiny protein factors) that we have on our red blood cells. These subtypes sometimes have names that may come from the original patient where they were discovered, such as K for Kell, Fy for Duffy and Jk for Kidd. Other names are derived from the alphabet, just as are A, B, O and AB. Some subtypes are so rare that only a few people in the whole world are known to have that subtype. We know of about 400 subtypes at this time.

You may have a Rare Blood Subtype!

The American Red Cross helps hospitals and doctors find suitable rare blood for patients who have had many transfusions and have reactions to routine blood transfusions. We need to match the donor blood to the patient's blood in many of the subtypes that are found in blood. Donors whose blood has been subtyped in our laboratories is often designated as "Rare" if all the subtypes it contains are not present very often in most donors.

We must test many donors to find the rare blood that our patients need. This takes many hours and sometimes we must call the American Rare Donor Program in Philadelphia if we cannot find the subtype of rare blood that we need. We will send you a letter and a special card if your blood is very rare.