I don’t grasp the Rh blood group system. Scanned textbook below.
50 antigens, lots of combinations (alleles), two genes. Five we care about especially: D, C, c, E, e. "D" defines Rh positive or negative.
But then textbook says:
Because the Rh alleles are inherited in groups of paired antigens, and each person has two chromosomes for the Rh antigens, each person has a total of five Rh antigens
Why five antigens ? With two genes and assuming both codominant that would make max four not five.
And what of two chromosomes? Each gene carried on separate chromosomes ?
I read somewhere all of it is carried on chromosome 1.