Figure 1: Standardization of RBC antigen genotyping by PCR-SSP (A) FY1, FY2, JK1, JK2, K1 and K2 alleles; (B) C, c, D, E, and e antigens; (C) M, N, S and s antigens: M1, M2, M3 and M4 represent amplification of different regions of GYPA responsible for M antigen specificity (as followed by Heymann and Salama, 2010). Presence of all the specific fragments accounts for the presence of M antigen. Similarly, N1 and N2 represent amplification of two regions of GYPA responsible for N antigen specificity. S/s polymorphism is due to a SNP, hence a single PCR each for S and s has been used for genotyping. PCR, polymerase chain reaction; SSP, sequence-specific primer; SNP, single-nucleotide polymorphism; RBC, red blood cell.