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Inherited Disorders and Birth Defects

Inheriting RH negative

08/20/2007

Question:

My parents are both RH Negative. We`ve always been told we would be RH negative also. But out of five sibling, three have been tested and all are positive. Is this possible?

Answer:

This question has been forwarded by Cancer Genetics:

In general, the Rh proteins are arranged into 2 groups - either positive or negative. Each person has two forms (allele) of the Rh gene and the positive form or allele is positive. People with 2 ++ alleles are Rh positive; people with one + and one - allele are Rh positive and people with 2 -- alleles are Rh negative.

Of the different combinations people can have - if both parents are Rh negative then all of their children should be Rh negative.

So you are correct, if both of your parents are Rh negative, you and your siblings should all be Rh negative.

For more information:

Go to the Inherited Disorders and Birth Defects health topic, where you can:

Response by:

Anne   Matthews, RN, PhD Anne Matthews, RN, PhD
Associate Professor of Genetics
School of Medicine
Case Western Reserve University