Which type of Hb is not affected by Rh isoimmunisation:

“An antigen frequently found in routine antenatal screening is the Lewis group (Lea and Leb). The Lewis antigens do not cause erythroblastosis fetalis and differ from all of the other red cell antigens in that they are not synthesized in the red cell membrane but are absorbed into it.” Fernando Arias 2/e, p 116