The father is blood type B and the mother is blood type O, but the child is blood type A? The truth is...

The father has type B blood and the mother has type O blood. The child was confirmed to be the right one in the hospital, but it turned out to be type A. In order to find out what was going on, the family went to Chongqing Zhengding Judicial Appraisal Institute to do a paternity test (DNA test).

The final result is: Dad! He is my biological dad! Mom! She is also my biological mom!

Why is this happening? Can blood type change at any time?

A person's blood type is determined by three alleles, A, B, and O, on a pair of chromosomes. A and B are dominant genes, and O is a recessive gene. Generally speaking, dominant genes are displayed:

A child's blood type is half inherited from the father and half from the mother. According to the rules of the conventional blood type inheritance table, if the father is type B, then the genotype is either BB or BO, and the mother is type O, so the genotype can only be OO. Then the child's genotype can only be BO or OO, there is no possibility of A?

Then why does a child’s blood type change so suddenly?

The truth is: Mom is not really type O blood, but a rare blood type: Bombay blood type. The biggest feature of Bombay blood type is that it hides the A and B genes in the blood.

The mother has a hidden A gene, and the child gets the A gene from the mother and the O gene from the BO blood type father, so the blood type is AO, which is displayed as A. So, except for this special case, will a person's blood type change?

Even the “unchanging” may change!

Generally speaking, a person's blood type is fixed at birth and remains unchanged throughout life. Therefore, if the father is type B and the mother is type O, the child can only be type B or type O, but definitely not type A. This is a basic rule, and it is true for most people. However, in some special cases, blood types may change:

In infants and young children, red blood cells are not yet mature and blood type antigens are not fully developed; in the elderly and patients with malignant tumors, the red blood cell antigenicity is weakened; patients receiving radiotherapy suffer from genetic changes in the red blood cell system; large amounts of colloidal solutions such as dextran are transfused in a short period of time to adsorb red blood cell surface antigens.

Image source: Pixabay

Of course, there is another situation where blood type can change, that is: the blood type test is wrong! So everyone must go to a professional institution for identification!

Source: Chongqing Institute of Population and Family Planning Science and Technology

Author: Liao Zhibin, Department of Laboratory, Affiliated Hospital of Chongqing Family Planning Research Institute

Audit expert: Chen Liang

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