Another Example of Phenotype Rh_null

Abstract

Blood‐donor typing provided the sixth example of a person with the rare phenotype, Rh null . Serologic investigation of the propositus and his family gives indirect support for the theory that the homozygous state of amorphic genes ( X 0 r/X 0 r) at a locus independent of Rh can block the production of the precursor substance upon which the Rh genes act to form the Rh antigenic determinants on red blood cells.