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BLOOD BASICS
or "Being O Negative in Singapore"

This page gives a basic introduction to the study of blood typing and considers its implications for ME: a person with blood type O-ve living in Asia. Well OK not just for me but that's an easy starting point for me to take.

What makes blood rare? Where are the various blood groups most predominant? Why are there different blood groups? Am I at risk? Are you? Well from what I've discovered, if you are -ve blood type, whether O, A, B or AB, you just might be.
Find out more.

GREAT QUOTE (The Economis June 3rd 1999):
"For the second time since December, a committee of scientists advised America's Food and Drug Administration to BAN BLOOD DONATIONS from anyone who has visited Britain since 1980 because of fears that they could be carriers of mad-cow disease."

 

INTRO

Every so often I receive an e-mail along the lines of:
"My father is dying. He needs O-ve blood. Please Donate!"

I don't usually tend to doubt the authenticity of the request, but I do wonder if it is a current one. Said father may have met his fate favourably or otherwise years ago.

And then I started thinking...

If O-ve blood group is in such short supply, what happens when I am in need?! I shall certainly have to take a bit more care or at least be prepared in case I may need to be on the receiving end of a transfusion one day.

 AM
I
AT RISK?


So why is blood type O-ve such gold dust?
There appear to be two key factors.

The combination of these two factors is such that those with O-ve blood have the smallest pool from which they can receive a donation IE, in the US, only about 6% of the population has compatible blood. On top of that, other blood groups may be dipping into our resources because our blood can be donated to almost anyone!

From the American Red Cross:
"44 percent of the population has type "O" blood making it the most common blood type. However there are often shortages of "O", especially "O" negative, because more than half the patients needing blood transfusions require "O" negative - and in most cases, they use more than one pint. Supply does not equal demand since donors can only give once every 56 days.

A shortage of type "O" blood is the worst of all blood shortages, because type "O" must be available to treat trauma patients as well as meet the transfusion needs of all type "O" patients. A shortage of type "O" blood is responsible for most emergency appeals."

So does that mean O negative blood is officially Rare? IT IS IN SINGAPORE!

  1. A blood type is considered rare when more than 200 donors have to be screened to find one compatible donor.
  2. Strictly speaking as O-ve constitutes up to 6% of the population in some places, it is not always rare.
  3. Usually, when we say someone has a rare blood type, what we really mean is that there is something special about their blood that goes beyond the ABO blood typing system (learn more about rare blood types here).
  4. But in Singapore, -negative blood of all types is very uncommon so you may be at risk!

 

So how? What can I do?

Donate Regulalry: if everyone did this, we would all have less worries about supply shortages!

Donate to Yourself. This is known as autologous transfusion.
But note:

  1. refrigerated blood only keeps for 42 days self donation is therefore not altogether practical: you would tend to only do it before an operation where there is potential for significant blood loss.
  2. If you truly have a very rare blood type then it might be possible to get your blood frozen as this keeps for up to 10 years.
  3. However the local blood transfusion service (blood bank) will not entertain such a suggestion except in extremely rare cases. I know I've asked them without success! (At the time I asked they said "Don't worry. We have 32 pints of O-Negative blood which is plenty."... that's for the entire nation!).

Direct Donation: Line up your donors. Now here's an idea!

  1. A directed donor is one who wishes his or her unit of blood to go to a specific patient.

  2. All directed donors must meet all regular donor criteria without exception.

  3. Basically what we're talking about is a short list that you compile of people with the same blood type. You can probably start with your family because it is likely (though not certain) that you have siblings or a parent who have the same blood type. Then you can move on to canvassing your friends. If you are really desperate, you can resort to finding people on the net.

  4. A WORD OF CAUTION - just because another person is O negative doesn't guarantee compatibility as in some cases other rare factors may come in to play.

 

 

If this intro leaves you wanting more detailed info,
then proceed to the facts and research section...
(there are some cool maps here!)
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GENETICS		 blood.jpg (2354 bytes)
ALLELE FREQUENCY		 blood.jpg (2354 bytes)
COMPATIBLE?		 blood.jpg (2354 bytes)
SINGAPORE

 

Facts and Quotes

ABO Blood group system:
The most important of blood-typing systems, the ABO blood group is the determinant for transfusion reactions and organ transplantation. Unlike the other blood-typing systems, the ABO blood types have far-ranging significance other than transfusion or transplantation, including the determination of many of the digestive and immunological characteristics of the body. The ABO blood group is comprised of four blood types: O, A, B and AB. Type O has no true antigen, but carries antibodies to both A and B blood. Type A and type B carry the antigen named for their blood type and make antibodies to each other. Type AB does not manufacture any antibodies to other blood types because it has both A and B antigens. Anthropologists use the ABO blood types extensively as a guide to the development of early peoples. Many diseases, especially digestive disorders, cancer, and infection, express preferences, choosing between the ABO blood types. These expressions are not generally understood or appreciated by either physicians or the general population. And if you think this is an oversimplification then click here smarty pants.

Why so many types?
"... Certain blood types are known to be more vulnerable to certain diseases, probably because the body can more readily recognize certain invading organisms. For instance O individuals seem relatively resistant to syphilis .... This may explain why virtually all American Indians (except for Eskimos and some northern Amerind groups) are type O, since syphilis is believed to have been introduced into the Old World by Columbus. Individuals with type A are more vulnerable to smallpox. Tuberculosis (pulmonary) is believed to be more virulent in A individuals than in O or B. Malaria shows a preference for A  individuals. Thus, it appears that balancing selection may exist for the ABO blood group." - Tracing the Genetic History of Modern Man (Web Source now broken).

What tests are performed on donated blood? After blood is drawn, it is tested for blood type and Rh type (positive or negative), as well as for any unexpected red blood cell antibodies that may cause problems in the recipient. Screening tests also are performed for evidence of infection with hepatitis viruses B and C, human immunodeficiency virus (HIV) 1 and 2, human T-lymphotropic viruses I and II and syphilis. The donor will usually be contacted if s/he tests positive for any of these factors.

How is blood stored and used?
Each unit of blood is separated into several components. Red blood cells may be refrigerated for up to 42 days or frozen for up to 10 years. Red cells carry oxygen and are commonly used to treat anemia.

Platelets are important in the control of bleeding and are generally used in patients with leukemia and other forms of cancer. Platelets are stored at room temperature and may be kept for up to five days.

 

Links

Misc References & Links

Blood Type Basics

Advanced Study

Blood Group Frequency

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This page was created 06-Aug-1999 by
 R.A.Rheaume