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Yes, this is possible. Don't forget each parent has a dominant gene and a recessive gene. If both of the parents carry a recessive gene in their blood for A- then it is possible for them to have a child with A+. I am a fraternal twin and my sister is B+ and I am B-. Draw a Punnett Square using a capital A for dominant and lower case a for recessive then cross reference the parents and you can determine the percentage for a group of parents to have an A- child.
yes, mother and father both carry recessive -
If the parents both carry the recessive gene form (allele) for the Rh gene then yes it is possible.
If dad was AA+- or Ao+- he could make a sperm cell that contained an A-. (possible sperm cells A+, A- in the first case & A+, A-, o+, o- in the second).
If mom also had either of the above genotypes she could produce an egg cell A- or o- and a baby with the phenotype (body) type A blood, Rh negative.
To set up the punnett squares:
dad AA+- with mom AA+- (dad always goes on top of punnett suare)
you get a 1 in 4 chance of a AA-- (type A negative baby)
dad Ao+- with mom AA+-
A+ A- o+ o-
you also get a 2 in 8 (1in4) chance of a type A negative child
dad Ao+- with mom Ao+-
A+ A- o+ o-
you get a 3 of 16 chance of a type A negative child
(Even a type AB+- father or mother could produce sperm and egg cells capable of making a Type A negative child.)
can a o+ mom and a o_ dad have an a_ baby
Yes it is possible, both parent must have a recessive - gene, therefore giving their child a 25% possibility of having a -
Both parent have a recessive - gene.
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