What does a negative blood type mean?

1 Answer
Suren Abreu
Dec 6, 2016

A negative blood type is one in which the D (or Rhesus) antigen is absent.

Explanation:

Apart from the four major blood groups, A, B, AB and O, there are sub-groups (sub-types) based on the presence or absence of the D (Rh) surface antigen.

If a person is genetically DD or Dd , the D surface antigen is expressed and the person is Rh positive.

If the person is genetically dd, the D surface antigen is not expressed and the person is Rh negative.

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