Duffy null

This code identifies a specific blood group phenotype where an individual lacks both Duffy antigens (Fya and Fyb) on their red blood cells. This genetic characteristic is often associated with natural resistance to Plasmodium vivax malaria.

This code is used when a patient's medical record explicitly documents a Duffy null phenotype, typically identified through blood typing or genetic testing. It is particularly relevant in cases involving transfusion medicine, hematology, or infectious disease, especially when considering malaria susceptibility or transfusion reactions.

• Ensure documentation clearly states "Duffy null" or "Fy(a-b-)" to support this code.
• Do not confuse with other Duffy blood group phenotypes (e.g., Duffy positive).
• This code may be used in conjunction with other codes indicating a related condition or reason for testing.