I have a question about blood types and seeming hereditary contradictions.
The above image of an Eldoncard blood test, which shows quite clearly that the testee has AB- type blood. (see image!). The sample comes from a person that has a father with blood type A (known from military), and a mother that has blood type O- (known from being a blood donor).
So the question is: how can a person have AB- in this situation (Mother with O-)?
There are a couple of possible scenarios:
- The Eldoncard ABO Rhesus D-test could be wrong, and the testee could have another blood type.
- The mother could have a weak manifestation of the B subtype, something which would show her as being O- while in fact being bO-, thus having been misdiagnosed as O-
- The father could actually have AB blood type, and in some rare circumstances, there have been examples of inheritance of blood type coming from only one parent.
Secondary question, though: If the mother has a weak manifestation of the B subtype, and this is how the testee got one B from her, wouldn't also they also have a weak manifestation of the B subtype - example Ab?
For the purposes of the question, assume that both parents are in fact the genetic parents of the testee.