Like the Fisher-Race theory, Wiener's theory cannot account for the complexity of the Rh system. The inheritance of the Rh system is not yet fully known. However, Rh genes have been cloned using the methods of DNA technology. Restriction fragment length polymorphism (RFLP) analysis suggests that Rh is controlled by two closely linked genes: one that encodes a polypeptide bearing the D antigen and a second that encodes C/c and E/e antigens. Unravelling the complexities of the Rh genome is currently an area of active research.
See this state-of-the-art review on the molecular biology of the Rh system.