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Maitri Vaishnav: The Bombay Blood Group and the Critical Role of the H Antigen
May 10, 2026, 18:04

Maitri Vaishnav: The Bombay Blood Group and the Critical Role of the H Antigen

Maitri Vaishnav, Student at C.U.Shah College of Pharmacy, shared a post on LinkedIn:

“Bombay Blood Group (Oh)

Definition

The Bombay Blood Group (Oh) is a rare blood group in which the H antigen is absent on red blood cells (RBCs).

Introduction:

  • Bombay blood group is a rare blood type.
  • First discovered in Bombay (Mumbai), India in 1952.
  • H antigen is responsible for formation of ABO blood groups.
  • In Bombay phenotype (Oh), H antigen is absent on RBCs.
  • Individuals produce Anti-H antibody.
  • They can donate blood only to other Bombay blood group individuals.

Genetics:

  • ABH gene is located on chromosome 9.
  • H gene (FUT1) is required for H antigen formation.
  • In Bombay group, FUT1 gene is inactive (hh).
  • Genotype of Bombay phenotype (Oh) is hh.

Antigen & Antibody:

  • Normal individuals (H present) don’t have Anti-H antibody
  • Bombay individuals (H absent) have Anti-H antibody present

Formation of H Antigen:

  • Precursor Substance
  • Reduced (FUT1 Gene / H transferase)
  • H Antigen

A Transferase presents as A Antigen

B Transferase presents as B Antigen

Without Transferase, H Antigen remains unchanged

Key Points:

  • Bombay group is also called Oh group.
  • Anti-H antibody is of IgM type.
  • Anti-H is not neutralized by saliva or secretions because H antigen is absent.
  • Important in blood transfusion and organ transplantation.

Importance:

  • Essential for safe blood transfusion
  • Helps identify rare blood groups
  • Important in blood bank and serological studies

Use:

Used in transfusion medicine, blood banking, immunohematology, and compatibility testing for safe blood transfusions.”

Maitri Vaishnav: The Bombay Blood Group and the Critical Role of the H Antigen

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