Being ccddee indicates me testing negative for the C, D and E antigens. Those are only 3 of the many within the Rh blood group system. If you lack all antigens from the rh blood group system, you are Rh null which is extremely rare. You are considered Rh Negative when the D is absent. There are however individuals with the C absent, but not the D. This is for everyone lacking the C:
The Rh blood group system consists of 49 defined blood group antigens.
One of them is the D antigen.
If you test negative for the presence of the D antigen, you are Rh Negative.
This is why Rh Negative is also often listed as Rh(D) negative or D negative.
If you test negative for the presence of ALL antigens of the Rh Blood Group System, you are RHnull.