Blood typing studies in American Indians: Misclassification of Rz phenotypes

Abstract The detection of exceptional Rh phenotypes (apparently (– –DE–)) among Venezuelan Yanomamo Indians initiated investigation of the reactions of anti‐C (rh′) sera with bloods of the R z phenotypes (CCDEE, CcDEE and CCDEe). It was concluded that since anti‐C reagents may contain differing amounts of two antibodies, anti‐C (rh′) and anti‐Ce (rh i ), the choice of reagent is critical for the detection of R z bloods, such that with an anti‐C serum containing large amounts of anti‐Ce relative to anti‐C, R z R 2 (CcDEE) will be mistyped as R 2 R 2 (ccDEE) and R z r (R 1 R 2 ‐CcDEe) may be mistyped as R 2 r (ccDEe). The error will have its greatest relative effect in populations characterized by substantial R z frequencies and the consequences of such an error (depressed R z gene frequency and elevated R 2 gene frequency) are therefore illustrated from published Indian studies.