Blood Typing

Types

• There are four types of blood due to the surface molecules present.

• These surface molecules are called antigens .

• The four types are: – A – B – AB – O

Importance

• Why do we need to know our blood type?

– Transfusion --Incompatible blood types could clump together and result in death.

– Cases of disputed parentage

Donating & Receiving Blood

Type: A B AB O Can give to:

A, AB

Can receive from:

A, O B, AB AB A, B, AB, O B, O A, B, AB, O O

Universals

• Universal Donor: Type O – Can donate blood to any blood type • Universal Recipient: Type AB – Can receive blood from any blood type

What does the + and – mean?

• The Rh factor genetic information is also inherited from our parents, but it is inherited independently of the ABO blood type alleles. • There are 2 different alleles for the Rh factor known as Rh+ and Rh-. • Someone who is "Rh positive" has at least one Rh+ allele, but could have two. Their genotype could be either Rh+/Rh+ or Rh+/Rh-. Someone who Rh- has a genotype of Rh-/Rh-.

Inheriting Blood Type

• Inherited from your mother & father.

• Caused by multiple alleles .

– (In other words, more than two alleles exist for a trait.) • Due to the presence or absence of certain molecules on the surface of red blood cells.

Blood Genetics

• The gene for blood type is “ I ”.

• There are three different alleles: – I A – I B – i • I A and I B are recessive.

co-dominant and i is – This means that neither A or B will block out the other.

Genotypes & Phenotypes

Phenotype Genotype(s)

A B AB O I A I A or I A i I B I B or I B i I A I B ii

Disputed Parentage

• A lady has a baby but is unsure of who the father is. The child has AB blood and the mother has type A.

• We know a man with Type O could not be the father.

blood • The father would have to have type B blood.

• Remember: Blood tests alone cannot prove a definite father, indicates only that he could be.

Practice

• Mom is heterozygous for type B blood. • Dad is heterozygous for type A blood.

• What are the possible blood types for their children?