How did my blood type go from O- to O+? I have records showing my blood type was O- but in 2012 it switched to O+. No blood transfusions at this point

Schematic representation of biosynthesis of blood group A, B

Blood types - NHS Blood Donation

ABO blood group system and the coronary artery disease: an updated systematic review and meta-analysis

Transfusion - Knowledge @ AMBOSS

What's the rarest blood type?

Associations between blood type and COVID-19 infection, intubation

Solved Blood types: The blood type o negative is called the

Transfusion - Knowledge @ AMBOSS

Blood Types: Main Groups, Most Common, and Rarest

Why can't a blood bank separate the 'A,' 'B,' and '+' and other