Blood Types

Blood types A and B are called "codominant" alleles, (they share in the controlling influence of our genetic Blood make-up) while O is "recessive." A codominant allele is apparent, or dominant, even if only one is present; a recessive allele is apparent only if two recessive alleles are present. Since Blood type O is recessive, it is not apparent if the person inherits an A or B allele along with it.


Therefore, there are certain possible allele combinations in a particular Blood type:

• OO = Blood type O
• AO = Blood type A
• BO = Blood type B
• AB = Blood type AB
• AA = Blood type A
• BB = Blood type B

What all of this means to the paternity puzzle is that ABO Blood typing can only give some preliminary indications as to possible paternity. This rule, however, can not be universally applied, because the vast majority of most people in Caucasian populations has only two of those types (A and O). This means that a male may have a type consistent with paternity and still not be the father of the tested child. DNA typing always yields a more reliable conclusion regarding paternity and is the final word in paternity legal cases

There are some good reasons for a husband to not donate Blood to his wife during her childbearing years. During this time, a women who plans to become pregnant, receiving Blood from her husband may pose a small risk to the infants born of these pregnancies. If, after the Blood transfusion the woman develops an antibody to an antigen on the father's red Blood cells, and the subsequently born fetus inherits the father's red cell antigen, the antibody from the mother may enter the Bloodstream of the fetus causing destruction of fetal red Blood cells. This may cause serious anemia in the fetus and excessive jaundice in the infant after birth. This is a known major cause of brain damage. Special Blood transfusions, using selected red Blood cells that do not have the particular in-compatible and offending antigen, are available when this condition is pre-diagnosed. Of course, we suggest autologous Blood donation for the mother. However, for those mothers who are unable to make an autologous donation, the decision to select her husband as a donor should always take this risk under consideration, and specific consultation with your pediatrician on this subject is essential.

There are instances when the following chart will not be accurate. In the case of a mutation, the Blood typings may not hold true in the question of parentage.

The chart should be used as general information only. All health care decisions should only be made with consultation from your physician. Ask before you act

PARENTS' BLOOD TYPES	POSSIBLE CHILD	NOT POSSIBLE CHILD
A and A	A, O	B, AB
A and B	A, B, AB, O	no
A and AB	A, B, AB	O
A and O	A, O	B, AB
B and B	B, O	A, AB
B and AB	A, B, AB	O
B and O	B, O	A, AB
AB and AB	A, B, AB	O
AB and O	A, B	AB, O
O and O	O	A, B, AB

Rh status works in a way similar to Blood type groups. If you are Rh positive, you may have genes for both positive and negative. If you are Rh negative, you have two genes for Rh negative. In the following chart, the child's Rh factor is in the white area.

	Mother's Group
Father's Group	Rh +	Rh -
Rh +	Rh +, Rh -	Rh +, Rh -
Rh -	Rh +, Rh -	Rh -

You are here : Home/ Blood Zone/ Blood Types

  Back