Dear Dr. Roach: I had a blood transfusion in 2000. Would the fact that someone else’s blood was used affect the results of a DNA test for ethnic breakdown for genealogical purposes? — H.P.S.

Answer: Mature red blood cells do not contain DNA, but early red cells do. Although it is possible to find a few persistent cells in some people within a week after blood transfusion using sophisticated testing, it is vanishingly unlikely that it would have any effect on commercial genetic testing for the purpose of mapping ancestry, which uses the cells from saliva. Even people with an organ transplant, with many cells from someone else, should have accurate results using this technique.

Dear Dr. Roach: I suffer with numerous cysts in my pancreas and from rough bouts of diarrhea and stomach bloating. Do you know of a physician that removes cysts from the pancreas, or are there other measures that I can take? The only thing my physician suggests is to take Creon, which I have been on for two or three years. — N.H.

Answer: It sounds like the primary problem with your pancreas is that it isn’t doing its major job, which is to secrete digestive enzymes into the intestines. Without those enzymes, you can’t properly digest foods, causing bloating and diarrhea (largely from fat not being absorbed). This condition is called pancreatic insufficiency. Creon is a brand of replacement pancreatic enzymes: These can reduce pain and dramatically improve digestion.

Cysts in the pancreas can be asymptomatic, but I am concerned that you may have chronic pancreatitis, which can cause not only the pancreatic insufficiency but also cystic structures in and around the pancreas (these usually are not actual cysts inside the pancreas, but pseudocysts outside it). A surgeon would be the person to evaluate whether pseudocysts need treatment. I would recommend that you get more complete information from your physician about the diagnosis and future management.