- Same basic oligosaccharide for blood group O
- A & B have extra, but different, terminal sugar
- N-acetyl-galactosamine for A, galactose for B
A sugar added by specific glycosyltransferase (GT) enzymes and the pattern is determined by which glycosyltransferase gene we carry.
There are two GT enzymes present (GTA and GTB) which are encoded for by different forms of the same gene. Blood group A produce GTA that put N-acetly-galctosamine on the surface of the red blood cells and blood group B produce GTB that put on galactose on the surface of the red blood cells .
In O blood group the GT is non-functional. AB blood group produces both GTA and GTB.
Rhesus Blood Group
Annotated as the Rh system, this involves grouping individuals by the presence or absence of the D antigen of the Rh blood group system. The D antigen is the most immunogenic of the Rh antigens. Patients are referred to as Rh+ or Rh- (positive or negative), according to whether or not they possess the D antigen. Rh+ individuals may only donate blood to other positive individuals. Rh- individuals may donate to both positive and negative recipients.