both parents have blood type of O

[bratface100]

if the child has b- blood type what type of blood does the parents have to have

[ed34]

I have no idea how rare it is, but I think there are more ways also where an O group could be the results in a test when in fact the patient is A or B.
Of course, the real fun starts when you try and give these poor patients a blood transfusion.

[curmudgen]

I guess it's never too late to learn something...In all the years that I taught basis human genetics I never ran into the lack of the attachment factor as a step in determining the final blood phenotype.  Sure make sense... now the question arises as to how common is it to lack this factor and to have occurred in sibs?  

[GoPens66]

Thanks...I had always kinda thought so....

[ed34]

OO xOO cannot have A children

Erm, well they can.
It's called something like recessive epistasis and involves sugars having the ability to attach to the cells. If the ability is missing, through genes, then an A will look like O in tests. The children may have the genetic ability to attach the sugars and be tested as A.  The parents may have the ability to create the sugars but not attach them.
Blood typing is not an accurate way to check parents at all, it requires a dna test.

[curmudgen]

Red_Star is not really correct in the genetic listings and ed is correct...

Original question was - child is B-  what could parents be?

BB and BB  ,  BO and BB , B0 and B0 , AO and BB , OO and BB , OO and BO,  OO and AB  all these could have a B child.  

Then there is rH factor  2 alleles for practical purposes - + and -
- - and - - , +- and - -  would have a negative child.

To GoPens66 - you are both A+ and your parents are O .... time to discuss this with your parents....  OO xOO cannot have A children.

[ed34]

WHAT?
This takes me back to my A level biology studies but I think the above chart is a bit naff. You can have a simple blood test to determine your type and factor, but this is only half the information with regards to your parents. We all inherit TWO alleles, and factors, one from each parent. The two don't mix and give us just ONE. We all have the possibility to pass one of TWO alleles and factors to our offspring, as does our partner. So, our offspring can obtain two out of a possible 4 alleles from us. For example, I am A+ but I have no idea what my other Allele is, because normal blood tests cannot tell you, it's in the genes. If I am A+ and O- and my wife is A+ and O-, our offspring will inherit either AA or AO or OO. When developing, the dominant type/factor will determine what the child will be, but the genes will still contain the TWO groups/factors to pass on. So the child in this case will become A+ because A is dominant and + is dominant. If you inherit AA or BB or AB from your parents, I believe you can become ANY group, including O. This is why normal blood grouping is not used in determining if you are with the right parents, it's far too inaccurate. The only way in genetic analysis.

[vienna13]

Great find Red_Star!

In my case correct for sure.:)

[Red_Star]

There are instances when the following the ABO blood chart will not be accurate. In the case of a mutation, the ABO blood typings may not hold true in the question of parentage. DNA testing can provide a 99.9% probability of paternity/maternity (depending on the type of samples used).

Parent's blood type = possible child's blood type

A and A =  A, O   
A and B =  A, B, AB, O  
A and AB = A, B, AB  
A and O =  A, O
B and B = B, O
B and AB = A, B, AB   
B and O = B, O  
AB and AB = A, B, AB  
AB and O = A, B  
O and O = O   

[GoPens66]

I hope someone know the answer to this because my sister and I are both A+ and our parents of O's.  I have always wondered about this.