A Negative (A-) Blood Type: Rarity Assessment
A negative blood type is considered relatively rare, occurring in approximately 6% of the U.S. population overall, though this frequency varies significantly by race and ethnicity. 1
Population-Specific Frequencies
The rarity of A- blood depends heavily on ethnic background:
In White non-Hispanic populations, A- blood occurs in approximately 6-7% of individuals, making it uncommon but not exceptionally rare 1
In Hispanic populations, A- blood is significantly rarer at approximately 2% frequency, as this group has a much lower overall Rh-negative rate (7.3%) compared to White non-Hispanics (17.3%) 1
In Black non-Hispanic populations, A- blood is similarly rare at approximately 2% frequency, as this group also demonstrates lower Rh-negative rates (7.1%) 1
In Asian populations, A- blood is extremely rare, as this group has the lowest Rh-negative frequency among major ethnic groups in the United States 1
Clinical Context for Blood Banking
From a blood banking perspective, A- blood presents moderate supply challenges:
A- donors are valuable because their blood can be given to both A+ and A- recipients, as well as AB+ and AB- recipients in emergency situations 1
The overall frequency of Rh-negative blood (all ABO types combined) is 17.3% in White non-Hispanic donors, 7.3% in Hispanic donors, and 7.1% in Black non-Hispanic donors 1
Blood group A overall (both positive and negative) represents approximately 34-40% of the U.S. population, making it the second most common ABO type after O 2, 1
Comparative Rarity
To contextualize A- blood type rarity:
More common than: AB- (which occurs in <1% of most populations), B- (1.3-1.8% in most groups), and O- in Asian populations (0.7%) 1
Less common than: A+, O+, B+, and O- in White populations (approximately 8%) 1
Significantly more common than: Rare phenotypes like K+k- in the Kell system (0.06%) or DCCEE in the Rh system (0.003%) 2
Geographic Variation
Regional differences affect A- frequency: