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# Is it possible for 2 parents to be rh-positive and have a rh-negative child? I know my grandmother was rh-negative, but no one else since, for 3 generations now. I am o positive, but my child was rh-negative. We so desperatly want and or need answers. We

4 doctors weighed in
Dr. Yvonne Thornton
Obstetrics & Gynecology
1 doctor agrees

## In brief: Good

Good evening: based on mendelian genetics, it is possible for two rh+ parents to have an rh- child.
Each one of us has two alleles (one from our mom and one from our dad). Homozygosity means that both genes are the same. Example: "t" = tall and little "t" = short. Homozygosity means you as a person has tt (two tall genes). If you were a heterozygote, you would have one tall gene (t) and one short gene (t), i.e., tt, but you would still be tall because the big t is dominant. It is the same concept with rh. You are a heterozygote for rh meaning you test positive but you have one recessive gene which was passed on to your child. This also means that your husband is a heterozygote and he passed his recessive gene to your child so that your child has two recessive genes and is rh negative. Your grandmother mated with an rh positive male (your grandfather) and your parent is a heterozygote which explains why you are also a heterozygote with the blood type o positive. I hope that answers your question.

## In brief: Good

Good evening: based on mendelian genetics, it is possible for two rh+ parents to have an rh- child.
Each one of us has two alleles (one from our mom and one from our dad). Homozygosity means that both genes are the same. Example: "t" = tall and little "t" = short. Homozygosity means you as a person has tt (two tall genes). If you were a heterozygote, you would have one tall gene (t) and one short gene (t), i.e., tt, but you would still be tall because the big t is dominant. It is the same concept with rh. You are a heterozygote for rh meaning you test positive but you have one recessive gene which was passed on to your child. This also means that your husband is a heterozygote and he passed his recessive gene to your child so that your child has two recessive genes and is rh negative. Your grandmother mated with an rh positive male (your grandfather) and your parent is a heterozygote which explains why you are also a heterozygote with the blood type o positive. I hope that answers your question.
Dr. Yvonne Thornton
Dr. Yvonne Thornton
Dr. Heidi Fowler
Psychiatry

## In brief: Yes,

Yes, two parents can be rh- positive and have an rh- negative child.
When it comes to the rh system, each parents genotype is made up of two parts. A parent could be rh -- (2 negatives), rh ++ (two positives) or rh +-. The rh positive is dominant over the rh negative. Therefore someone who has an rh + genotype could be either rh +- or rh ++. So if both parents were rh+- they would each be considered rh+ genotype. If each of those parent's contributed a (-) negative to the fetus, the baby would be rh-- and thus she would have an rh negative blood type. I know this can seem a little complicated. Hope it helps to take some of the apprehension away.

## In brief: Yes,

Yes, two parents can be rh- positive and have an rh- negative child.
When it comes to the rh system, each parents genotype is made up of two parts. A parent could be rh -- (2 negatives), rh ++ (two positives) or rh +-. The rh positive is dominant over the rh negative. Therefore someone who has an rh + genotype could be either rh +- or rh ++. So if both parents were rh+- they would each be considered rh+ genotype. If each of those parent's contributed a (-) negative to the fetus, the baby would be rh-- and thus she would have an rh negative blood type. I know this can seem a little complicated. Hope it helps to take some of the apprehension away.
Dr. Heidi Fowler
Dr. Heidi Fowler
Dr. George Klauber
Pediatrics - Urology

## In brief: Absolutely Yes

You had a 1:4 chance of having a rh -ve baby & same odds for any future baby with same father. Both parents have to be heterozygous for rh factor, ie each parent has both an allele (group of genes which determine a characteristic like eye color or rh) for rh =ve & one for rh -ve.
If either parent was homozygous (both alleles similar) all offspring would be rh +ve. Hope this simplified info helps.

## In brief: Absolutely Yes

You had a 1:4 chance of having a rh -ve baby & same odds for any future baby with same father. Both parents have to be heterozygous for rh factor, ie each parent has both an allele (group of genes which determine a characteristic like eye color or rh) for rh =ve & one for rh -ve.
If either parent was homozygous (both alleles similar) all offspring would be rh +ve. Hope this simplified info helps.
Dr. George Klauber
Dr. George Klauber
Dr. Michael Opsahl
Fertility Medicine

## In brief: It

It is possible for rh positive parents to have and rh negative child.
You each have 2 genes for rh. Rh is a dominant gene which means that if each of you have 1 rh pos gene and 1 rh neg gene then you have a 25% chance of having an rh negative child. See http://bit.Ly/zymrst for a more detailed discussion. I hope this information helps you understand the genetics of rh. If you have more questions, you should see a geneticist. Best wishes.

## In brief: It

It is possible for rh positive parents to have and rh negative child.
You each have 2 genes for rh. Rh is a dominant gene which means that if each of you have 1 rh pos gene and 1 rh neg gene then you have a 25% chance of having an rh negative child. See http://bit.Ly/zymrst for a more detailed discussion. I hope this information helps you understand the genetics of rh. If you have more questions, you should see a geneticist. Best wishes.
Dr. Michael Opsahl
Dr. Michael Opsahl
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