The term "null type" for the RBCs describes a condition in which all of a person's RBCs are negative for all of the factors in a single blood group system, eg, Kell, Rh, Kidd. The hereditary absence from the cell surface of expected RBC antigens can be due to a suppressor gene that is preventing phenotypic expression of the genetically transmitted trait, or can be due to a recessive "amorphic" gene that, in the homozygous state, provides a void where the common antigen usually resides. A listing of 20 kinds of null RBC types has been made1 of which the most striking is the total Rhnull.
Ten years ago a hemolytic anemia was reported in an Rhnull proposita living in Virginia.2
Hemolytic anemia has now been proved in all Rhnull propositi and has been described as well for nulls in other blood group systems. The