Bombay Phenotype (Oh, Hh)
Definition
Y. M. Bhende, 1952, K.E.M. Hospital Mumbai. Homozygous absence of the H antigen, so neither A nor B can be expressed; types as O on routine grouping, but serum contains anti-H.
- First described by
- Y. M. Bhende, 1952
- Location
- K.E.M. Hospital, Mumbai
- Genotype
- Homozygous hh, absent H antigen
- Routine typing result
- Appears as group O
- Serum finding
- Contains anti-H antibody
Common questions
Why does the hh genotype block expression of both A and B antigens?+
The H antigen is the precursor structure onto which the A and B transferase enzymes attach their respective sugars. Without a functional H antigen, an individual's A or B genes have nothing to modify, so no A or B antigen appears on the red cells regardless of which ABO alleles are present.
Is the Bombay phenotype more common in any particular population?+
It was first reported in Mumbai and remains more frequently documented on the Indian subcontinent than in most other populations, though it has since been reported worldwide at very low frequency, often traced to communities with a history of consanguineous marriage.
Related terms
- ABO System
- The blood-group classification described by Karl Landsteiner in 1901: groups A, B, AB, and O, defined by antigens on red-cell surfaces and...
- Agglutination
- Clumping of red cells that occurs when antibodies in serum bind to incompatible antigens on the cell surface, cross-linking cells into visible...
- Antibody (Isohaemagglutinin)
- An immunoglobulin in plasma directed against red-cell antigens the host does not carry. Group O serum carries anti-A and anti-B; group AB...
- Antigen
- A molecule recognised by the adaptive immune system through specific binding to an antibody or T-cell receptor. Defined by immunogenicity (capacity to...
- ISBT
- International Society of Blood Transfusion. The authority that catalogues and numbers the 35+ recognised blood group systems.
- MNS System
- A blood group system comprising M and N antigens on glycophorin A (GYPA) and S and s antigens on glycophorin B (GYPB)....
- Rh System
- A blood group system defined by antigens on two proteins encoded by the RHD and RHCE genes on chromosome 1. The clinically...
- Secretor Status
- A genetic trait that determines whether a person expresses their ABO blood group antigens in secreted body fluids such as saliva, semen,...