The following four mechanisms are responsible for weakened expression of the D antigen:
1. C in trans to RHD
2. Weak D
3. Partial D
4. Del
A discussion of each mechanism is presented in the following pages.
Harmening, DM,: Modern Blood Banking & Transfusion Practices, 6th ed. FA Davis, Philadelphia, PA, 2012, p 158-160.
Blaney, KD and Howard, PR: Basic & Applied Concepts of Blood Banking and Transfusion Practices, 3rd ed. Elsevier, St. Louis, MO, 2013, p 112-116.