Hidden Variants: Exploring Uncommon Blood Phenotypes

Abstract

The Bombay blood group (Oh phenotype) is a very rare and clinically important blood type. It was first identified in 1952 in Mumbai by Y. M. Bhende. Unlike the common ABO blood groups, people with this phenotype do not have the H antigen on their red blood cells. The H antigen is necessary for the formation of A and B antigens. It is normally produced by an enzyme controlled by the FUT1 gene. In individuals who inherit two non-working copies of this gene (h/h), the H antigen is absent. As a result, they may appear to have blood group O in routine testing.
However, these individuals produce strong anti-H antibodies along with anti-A and anti-B antibodies. Because of this, they cannot receive blood from A, B, AB, or even O donors. Transfusion of incompatible blood can cause severe hemolytic reactions, kidney failure, or even death. This case emphasizes the need for careful blood grouping, including reverse typing, to avoid dangerous transfusion errors.