ISBT Numeric Terminology

A universal language related to phenotypes was needed based on the global sharing of blood products. The International Society of Blood Transfusion (ISBT) established a uniform nomenclature that is eye- and machine-readable and kept with the genetic basis of blood group systems.

This terminology adopts a six-digit number for each authenticated antigen belonging to a blood group system. The first three numbers represent the system (Rh system = 004), and the last three represent antigenic specificity. In addition, a given antigen may be written using an alphanumeric designation with the blood group system in uppercase letters followed by the number assigned to the antigenic specificity.