Anti-Rh and anti-K in SWiTCH patients at trial enrollment. (A) The number and specificity of antibodies identified in 27 patients who are either negative or positive for the corresponding antigen by serologic testing. (B) The number of patients with partial Rh antigens (and no corresponding conventional allele) determined by high-resolution RH genotyping and at risk of alloantibody (n = 27 Rh alloimmunized and 27 non-alloimmunized at enrollment).