AB Negative Blood Type: Rarity, Inheritance, and Transfusion Facts

AB negative is the rarest ABO/Rh blood type, present in ~0.6–1% of populations (varies by ethnicity).

Genetics

• ABO: IA and IB alleles (codominant).
• Rh: RhD negative = homozygous deletion/nonfunctional RHD.

Transfusion Compatibility

• Red cells: Can receive from all Rh-negative types (O−, A−, B−, AB−). Universal plasma donor (AB plasma lacks anti-A/anti-B).
• Plasma: Can receive only AB plasma.

Clinical Significance

• Rare donor programs critical for AB− patients.
• Pregnancy: Rh− mothers need RhIg prophylaxis.
• No disease susceptibility linked to ABO/Rh type alone.