What’s my blood type?

In con­junc­tion with World Blood Donor Day yes­ter­day, we take a look at the im­por­tance of your blood group.

The Star Malaysia - Star2 - - Health -

I FI­NALLY tested my blood type in school dur­ing a health screen­ing. They told me that I am A pos­i­tive. How many blood types are there?

It de­pends on the clas­si­fi­ca­tion you use.

Most peo­ple com­monly use two types of clas­si­fi­ca­tions: the ABO blood group clas­si­fi­ca­tion and the Rh­e­sus blood group clas­si­fi­ca­tion.

So, our blood types are usu­ally clas­si­fied ac­cord­ing to both these sys­tems.

There are ac­tu­ally 35 dif­fer­ent blood group clas­si­fi­ca­tions that have evolved over time!

How are these clas­si­fi­ca­tions made?

Take your red blood cells. They are spher­i­cal cells that carry oxy­gen and nu­tri­ents to your en­tire body.

But they also have 30 dif­fer­ent sub­stances on their sur­faces that make up all sorts of blood group anti­gens.

Your blood type is de­ter­mined by one of the many pos­si­ble com­bi­na­tions of these anti­gens.

Over 600 dif­fer­ent blood group anti­gens have been doc­u­mented, which are utilised in dif­fer­ent com­bi­na­tions in the 35 blood group clas­si­fi­ca­tions.

Nev­er­the­less, we usu­ally use the ABO and Rh­e­sus clas­si­fi­ca­tions, as they are the most com­monly-ac­cepted ones, so as not to com­pli­cate mat­ters, es­pe­cially when it comes to blood do­na­tion.

Some rarer blood group types are linked to cer­tain dis­eases.

For ex­am­ple, if your blood type lacks a cer­tain anti­gen called the Duffy anti­gen, you will be re­sis­tant to cer­tain species of malaria.

What is the ABO clas­si­fi­ca­tion?

In this clas­si­fi­ca­tion, there are two anti­gens in your red blood cells called anti­gen A and anti­gen B.

There are also two an­ti­bod­ies called an­ti­body A and an­ti­body B, which are present in your blood serum.

The type of anti­gen(s) you have de­ter­mines your blood group, as fol­lows:

Anti­gen A – Blood group A

● Anti­gen B – Blood group B

● Both anti­gen A and anti­gen B – Blood group AB

Nei­ther anti­gen A nor anti­gen B – Blood group O

When you have a cer­tain anti­gen, you will usu­ally have the op­po­site an­ti­body present.

For ex­am­ple, if you have anti­gen A, you will have an­ti­body B.

If you have both anti­gen A and B, you will have no an­ti­bod­ies.

And if you have no anti­gens, you will have both an­ti­bod­ies A and B present.

Why are these an­ti­bod­ies im­por­tant?

It is im­por­tant to know that these an­ti­bod­ies ex­ist be­cause this is the ba­sis of blood trans­fu­sion.

Blood trans­fu­sion is safe for you as long as the donor’s blood does not con­tain an­ti­bod­ies against your blood anti­gen.

Oth­er­wise, the anti­gen and an­ti­body will “fuse to­gether” in a re­ac­tion called ag­glu­ti­na­tion, which will cause a trans­fu­sion re­ac­tion and pos­si­bly re­sult in the per­son go­ing into shock.

For ex­am­ple:

If you are blood group A, you will have anti­gen A and an­ti­body B.

An­ti­body A will ag­glu­ti­nate anti­gen A.

So, only a donor’s blood with­out an­ti­body A will be safe for you.

There­fore, you can only re­ceive blood from donors who have blood group A or O.

Peo­ple with blood group AB can tech­ni­cally re­ceive blood from all other blood groups.

And peo­ple with blood group O can only re­ceive blood from other peo­ple with blood group O.

But it gets more com­pli­cated be­cause we also have to take into ac­count the Rh­e­sus clas­si­fi­ca­tion!

What is the Rh­e­sus clas­si­fi­ca­tion?

The Rh­e­sus sys­tem ac­tu­ally has 50 anti­gens!

But the most im­por­tant anti­gen you have to re­mem­ber is the D anti­gen, be­cause it is the one most likely to pro­voke an im­mune re­sponse when you trans­fuse the wrong blood type.

You are ei­ther D-pos­i­tive (mean­ing you have the D anti­gen), or D-neg­a­tive (mean­ing that you don’t).

Usu­ally, this is writ­ten as just “+” or “-”.

Com­bine this with the ABO clas­si­fi­ca­tion, and you have the eight blood group types that we com­monly use to­day:

● A+

● A

● B+

● B

● AB+

● AB

● O+

● OPeo­ple with the O- blood group can do­nate blood to any­one. They are called uni­ver­sal donors.

But those with the AB+ blood group can­not do­nate blood to any­one ex­cept other peo­ple with AB+ blood. They are called uni­ver­sal re­cip­i­ents.

Is my blood type for life, or do peo­ple change blood types over time?

Most peo­ple have the same blood group for life.

But in rare cir­cum­stances, you can change your blood group if an anti­gen is added or sup­pressed.

This hap­pens when you have a bone mar­row trans­plant, es­pe­cially from a donor with a dif­fer­ent blood group.

Even­tu­ally, you will con­vert to your donor’s blood type.

Dr YLM grad­u­ated as a med­i­cal doc­tor, and has been writ­ing for many years on var­i­ous sub­jects such as medicine, health, com­put­ers and en­ter­tain­ment. For fur­ther in­for­ma­tion, e-mail starhealth@thes­tar.com.my. The in­for­ma­tion con­tained in this col­umn is for gen­eral ed­u­ca­tional pur­poses only. Nei­ther The Star nor the au­thor gives any war­ranty on ac­cu­racy, com­plete­ness, func­tion­al­ity, use­ful­ness or other as­sur­ances as to such in­for­ma­tion. The Star and the au­thor dis­claim all re­spon­si­bil­ity for any losses, dam­age to prop­erty or per­sonal in­jury suf­fered di­rectly or in­di­rectly from reliance on such in­for­ma­tion.

Dur­ing blood do­na­tion drives, a chart like the one in this filepic, is used to de­ter­mine a per­son’s blood type by see­ing which an­ti­body re­acts with the per­son’s anti­gens.

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