Bombay phenotype (Symbol Oh), popularly well-known as Bombay blood group was first discovered by Y M Bhende et al in 1952 at Bombay (now known as Mumbai). It is a rare phenotype which shows absence of A, B, H antigens on red cell membrane and presence of anti-A, anti-B and anti-H antibodies in serum. H antigen on RBCs is the precursor structure on which ABO genes act to produce A and B antigens. As H antigen is absent, no A and B antigens are produced. Bombay phenotype (Oh) lacks normal expression of the A, B and H antigens because of the inheritance of the hh genotype. Their blood is incompatible with any other blood groups, except blood of another Bombay if they need blood transfusion. Prevalence of Oh is 1 per 10,000 in India and 1 per 1,000,000 in Europe. In Bangladesh, it is 1 per 0.006%. We found a first case of Bombay phenotype at TMSS Medical College, Bogura, which was confirmed by testing of blood and saliva using anti-H lectin.

A Rare Blood Group, Antigen, Bombay phenotype

Bombay phenotype (Symbol Oh), popularly well-known as Bombay blood group was first discovered by Y M Bhende et al in 1952 at Bombay (now known as Mumbai), India. This is the reason why this type of blood got the name Bombay phenotype. Tt is a rare phenotype which shows absence of A, B, H antigens on red cell membrane and presence of anti-A, anti-B and anti-H antibodies in serum." The molecular basis of this blood group has been proven to be mutations of the FUT1 gene (H gene) which results in the formation of complete H-deficient phenotype (genotype hh)."2 After the cloning and characterization of the FUTI gene in 1990 and proving that the gene was the molecular basis of the Bombay phenotype in 1994, the H blood group system was established. The H blood group system, ISBT symbol H (018), consists of a single antigen (H) defined by a terminal fucose residue found on red blood cells and in secretions. The H gene must be inherited to form ABO antigens on the RBCs. Inheritance of the H gene (genotype HH or Hh) results in the formation of the H antigen. The H antigen on RBCs is the precursor structure on which ABO genes act to produce A and B antigens. If H antigen is absent, no A and B antigens are produced. The term Bombay has been used to refer to the phenotype that lacks normal expression of the A, B and H antigens because of the inheritance of the hh genotype.