Incidental Discovery of a Patient with the Bombay Phenotype

Abstract

Bombay phenotype, an exceptionally rare blood type in individuals outside of Southeast Asia, occurs in approximately 1 in 1,000,000 individuals in Europe. This blood phenotype is characterized by the absence of the H antigen on red blood cells (RBCs) and in secretions. As the H antigen is the structure on which the ABO system is built, individuals lacking this antigen are unable to produce A or B antigens and appear as type O on routine ABO phenotyping. H deficiency does not cause ill effect; however, these individuals produce an anti-H alloantibody capable of causing severe acute hemolytic transfusion reactions when exposed to RBCs that express the H antigen. In this case study, we highlight the incidental discovery of a patient with Bombay phenotype in a North American hospital system, expected test results, the immunologic and genetic basis underlying the Bombay and para-Bombay phenotypes, and methods to ensure availability of compatible blood.

Discordance between ABC blood phenotype and genotype in a domestic short‐haired cat

“…The fact that NeuAc appears not absorbed or synthesized and at the same time the CMAH enzyme is also mutated, might indicate that CMAH is further changed to a precursor antigen different than NeuAc or NeuGc. Overall, these blood type studies bear similarities with an unusual “weak B ” phenotype or the exceedingly rare Bombay‐like phenotype of the human ABO blood group system, although a precursor substrate analogous to the H antigen in the ABO system has yet to be identified in cats 8,9 …”

“…Overall, these blood type studies bear similarities with an unusual "weak B" phenotype or the exceedingly rare Bombay-like phenotype of the human ABO blood group system, although a precursor substrate analogous to the H antigen in the ABO system has yet to be identified in cats. 8,9 Humans with the Bombay phenotype appear to type as group O by the ABO testing, regardless of their ABO genotype, as they lack the H-antigen scaffold on RBCs to form the A and B antigen. 7 Therefore, when anti-A and anti-B reagents are matched against their RBCs, no agglutination is seen, but they produce antibodies against the A and B RBC antigens, as well as express a clinically important anti-H titer.…”

“…Therefore, when anti‐ A and anti‐ B reagents are matched against their RBCs, no agglutination is seen, but they produce antibodies against the A and B RBC antigens, as well as express a clinically important anti‐H titer. Individuals with the Bombay phenotype must only receive H antigen‐negative blood 9 . In this cat, testing against the precursor substrate was technically not possible.…”

“…This blood type is characterized by the absence of the H antigen on RBCs. As the H antigen is the substrate on which the A and B antigens are formed, the individuals lacking this antigen are unable to produce A or B antigens and appear as type O on routine ABO phenotyping, regardless of their ABO genotype 7‐9 …”

“…antigen are unable to produce A or B antigens and appear as type O on routine ABO phenotyping, regardless of their ABO genotype. [7][8][9] In this case report, blood type studies that resemble the exceedingly rare Bombay phenotype or a weak type B are described in a domestic short-haired cat. Due to the severe, likely chronic kidney disease (international renal society-based stage IV, with proteinuria), the cat was hospitalized.…”