Ask Dr. H: Type B-blood parents can have type-O son

Posted: August 01, 2011

Question: Recently, our son needed an operation and had his blood identified as type O. My wife and other son, as well as myself, are type B. How can parents with the same blood type produce a child with a completely different type?

Answer: It's totally possible for you and your wife to be type B and to have a son who's type O. When we refer to blood types like A, B, and O, we're describing the presence or absence of A or B "antigens" - protein substances found on the surface of your red blood cells.

A person who is type O has no A or B antigens on his red blood cells. "Rh" is another antigen that may or may not be on the surface of red blood cells. Someone with that antigen is "Rh positive"; without it, "Rh negative." A, B, and Rh are the major antigens that may be present on red blood cells, but there are nearly 600 other minor antigens to which some people might react during a blood transfusion.

When people get their blood typed, it's either A+ (the "+" means Rh is present) or A-, B+, B-, O+, O-, AB+, or AB-. Every person inherits half the genetic information that determines his or her blood type from the mother and half from the father.

A person who is type A may have inherited an A antigen from each parent (genetically AA) or a single A antigen from one parent and no antigen from the other (AO). Both AA and AO are considered type A. The same scenario applies if a person is type B.

If a person is type O, however, there are two possibilities: 1) both parents are type O and genetically OO (meaning no A or B antigens on the red blood cell surface); or 2) neither parent is pure genetic A or B, but genetically AO or BO, with each passing on an O so that their child ended up as type O (genetically OO).

In your case, you and your wife presumably are both type B and genetically BO. So each of you passed on genetic information for one of your O's to your son - and he is genetically type OO.

With diverticulitis, still a need to forgo seeds?

Q: When I was diagnosed with diverticulitis, I was advised against eating any nuts, popcorn, or seeds. My doctor at the time advised me to stay away from hard seeds as well as soft seeds. Now I see there's controversy regarding the need to avoid seeds. What is your opinion?

A: First, a point of clarification: Diverticulosis refers to the nooks and crannies that are tiny, fingerlike pockets ballooning out through the colon's muscular wall. Some people have none; others have dozens. Diverticulitis is an infection of one or more of those diverticuli sacs.

Diverticuli don't empty well; stool can get trapped in the sacs, which can become infected and inflamed. This causes abdominal pain, typically in the left lower abdomen because diverticuli usually are present on that side.

For someone with diverticulosis, eating large amounts of fiber and roughage helps to keep the pipes clean. In fact, it's a Western, low-fiber diet that increases the chances of developing diverticular disease. But when diverticulitis is present, the last thing you'd want to do is consume high amounts of fiber or roughage. That will further inflame and injure the colon.

For years, doctors have said nuts, popcorn, and anything with seeds should be avoided for both diverticulosis and diverticulitis. Because obstruction of the diverticular sac is associated with complications, it has been suggested that avoiding foods with seeds or nuts (such as popcorn, pomegranates, or strawberries) will reduce the risk of complications.

Although this makes sense, there is no research evidence that the risk of complications is reduced by avoiding seeds. In fact, a Harvard School of Public Health study of 47,228 male health professionals between the ages of 40 and 75 who had no history of diverticulosis/diverticulitis found that men who ate nuts, corn, or popcorn frequently had no greater risk for developing diverticulitis than men who rarely ate those foods.

A general rule is that small amounts of these foods are probably fine. If you know certain foods aggravate your diverticular condition, however, just avoid them.

Mitchell Hecht specializes in internal medicine. Send questions to him at: "Ask Dr. H.," Box 767787, Atlanta, Ga. 30076. Because of the l volume of mail received, personal replies are not possible.

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