The Bombay route of blood

By Dr Anjana Kannankara The importance of knowing one’s blood type is crucial due to various reasons. It can be useful to prevent the risk of receiving an incompatible blood type or to get timely medical assistance at times of need such as blood transfusion and surgeries. The information about blood type can be a significant tool for understanding how the body reacts to food, susceptibility to diseases, natural reaction towards stress, the aging process and much more. Normally, blood group is of 4 types — A, B, AB and O. It is compulsory to identify and match blood groups before donating or receiving blood, otherwise it can be dangerous or even worsen the health problems. In this article, we will have a quick look about the rare blood group known as ‘Bombay Blood Group’, as part of creating awareness that in turn might be helpful in saving lives. What is Bombay blood group The h/h blood group, also known as Oh or the Bombay blood group, is a rare blood type. It fails to express A, B or H antigen on their red cells or other tissues. To understand more about Bombay blood group we must understand the details of blood grouping. When someone has blood group A, it means that the person has antigen of type ‘A’ and antibody of type ‘B’ in his/her blood. People with AB have both antigen A and B in their blood and no antibodies. People with O blood group have only antibodies A and B and no antigens. However what is not generally known is that all these groups have an antigen H in the blood as well. There are very few people who do not have this antigen H in their blood. Instead they have antibody H because of which no other blood can be given to them. This is the Bombay blood type. This blood phenotype was first discovered in Bombay, now known as Mumbai, in India, by Dr YM Bhende in 1952. It is mostly confined to the region of Southeast Asia — India, Bangladesh, Pakistan and Iran. It is observed to occur in 1 out of every 250,000 people except in parts of India where the incidence has been observed to be as much as 1 in every 10000. It is estimated that only 4 per million people in the world have this blood type. All the blood groups primarily contain a protein called the H antigen. The antigens A and B are made from the H antigen. Bombay blood group is also called the HH group. The peculiarity is that they do not express the H antigen. As a result they cannot form A antigens or B antigens on their red blood cells. They only have the ‘H’ antibody which none of the other blood groups have. They can donate blood to anybody with ABO grouping but can receive blood only from people with Bombay blood group. Hence, it is observed they could be included in the category of universal donors. Reverse grouping or serum grouping has to be performed to detect the Bombay blood group. This can identify the H antibody using anti-H Lectin reagent. During cell grouping or forward grouping, Bombay blood group would be categorised as O group because it would not show any reaction to anti-A and anti-B antibodies just like a normal O group would do. Serious hemolytic transfusion reactions occur that might result in death hence matching of blood type is absolutely essential before transfusion. If two different blood types are mixed, it can lead to a clumping of blood cells that can be potentially fatal. Persons with this blood group must be very cautious and alert. Registering themselves with various blood banks and hospitals would ensure the availability of the same blood group in times of emergency. During surgeries prior arrangement for sufficient blood availability could be ensured with proper planning. Proposals to keep a few units of such blood in frozen state (cryopreservatio) can be considered for acute emergencies. Contact the blood banks and organisations that arrange blood donation to trace people with similar blood type. If required, messages can be forwarded to those in other cities too. Check the details of blood groups of all family members as mostly this blood group is found among closely related people. Advertising in the media could also help greatly considering the rarity of the blood. (The author is director-TGL Foundation, editor-Anthropology Today and senior director-FWO)