Bombay Blood Group

Bombay blood group is a rare blood group first discovered in Mumbai (then Bombay) in 1952 by Dr Y M Bhende.

How it is different from ABO Blood Group System?

A, B, AB and O are the four most common blood groups. Each blood group is characterized by a presence of antigen which determines which group it belongs to. In the AB blood group, both antigens A and B are found. A will have A antigens; B will have B antigens.

The Bombay Blood group (hh) is deficient in expressing antigen H .i.e. the RBC has no antigen H.

Often the Bombay Blood Group is confused with the O group. The only difference is that the O group has Antigen H, while the Bombay blood group does not.

Rare Presence

Globally, the Bombay blood type has an incidence of one in four million with a higher incidence in South Asia. In India, one in 7,600 to 10,000 are born with this type. The blood type is more common in South Asia than anywhere else because of inbreeding and close community marriages. As a result of which it is genetically passed.

Difficulties in Transfusion

A study in the Asian Journal of Transfusion Science has observed that “The individuals with Bombay blood group can only be transfused autologous blood or blood from individuals of Bombay hh phenotype only which is very rare.”

Rejection may occur if they receive blood from A, B, AB or O blood group. In contrast, hh blood group can donate their blood to ABO blood types.

An unofficial registry for Bombay blood group has listed over 350 donors across India. But at any time there are only 30 active donors available.

Since it is rare and the shelf life of blood is 35-42 days, this group is generally not stored in blood banks. As a result, whenever there is a demand for a Bombay blood group patient, a donor is required very urgently and sometimes facilities need to be created for transporting the donated blood from one city to another. A few weeks ago patient in Kota got hh blood from a Pune-based donor. The blood was flown to Jaipur and taken to Kota hospital by road.

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