by Ayush G Punwatkar and Jay Bhoyar
T.Y.B.Sc Department of Biotechnology DES Fergusson College, Pune. For BTH3507
Blog Category: Hematology
Till today four main blood types were identified namely A, B, AB, and O. Universal donors have type "O" blood, and have no "A" or "B" antigens. In turn, no blood reactions will occur in recipients. Conversely, universal recipients having type "AB" blood will have no antibodies to the "A" or "B" antigens. ‘A’ Blood group carrying people contain RBCs having surface antigen as A and people with B blood group contain RBCs having surface antigen as B. Bombay phenotype has no "A" or "B" antigens, classifying it as "O" blood type but problem is that Bombay phenotype lacks expression of the H antigen, which is present on every blood cell. Thus making it as a completely different Blood group.
The Rarest blood type – Bombay blood group
What is Bombay blood group? Bombay blood group is a very rare blood group. The cause behind this is that it is due the point mutation in H gene. Person carrying two mutant ‘H’ gene results in Bombay blood group. It was first discovered by Dr.Bhende in Bombay, India in 1952 so name as Bombay blood group. The incidence of this is about 1 in 10,000 in India and 1 in 106 in Europe. The normal H gene codes a protein called as fucosyltransferase. Thus in case of Bombay blood group their is point mutation in H gene results in mutant h gene which does not codes for for any protein thus there is lack of production of protein fucosyltransferase. This protein catalyses the addition of L-fucose to the precursor chain to form ‘H’ antigen. So the patient with Bombay blood group cannot produced ‘H’ antigen due to lack of protein Fucosyltransferase. These type of people also don’t carry ‘A’ and ‘B’ antigen along with H antigen that’s why these type of people produced anti-A, anti-B, and anti-H antibodies when encounter the blood transfusion with any of these blood group. Reason behind the lack of A and B antigen although there is presence of ‘A’ and ‘B’ gene is that ‘A’ and ‘B’ genes adds N-acetlyglusasamine and D- galactose toto the ‘H’ antigen to form ‘A’ and ‘B’ antigen so due to the mutation in ‘H’ gene these types of reaction cannot takes place.
Bombay blood group mimic ‘O’ blood group but difference between these blood is that in Bombay blood group there is production of anti-H antibodies so this blood group show cross reaction with all blood groups .The patients carrying these type of blood group only receive blood from person carrying Bombay blood group but they can donate their blood to anyone this make them Universal blood donor. There were many emergency cases that had occurred in past in which blood was arranged with very difficulty from other states or even from other countries because there is very low incidence of this type of blood in the Population. But in very emergency condition the fresh frozen plasma, platelets and cryoprecipitate can be transfused in the body of the patients. Autologous blood transfusion is another option for a patient with Bombay blood group but this method cannot be performed if the patient is dealing with low hemoglobin count.
Statistics
In the general population the prevalence of Bombay blood group is about 1 in 10,000 individuals in India and 1 per 1,00,000 individuals in Europe. Although in some places of Mumbai (formerly Bombay) the prevalence of this phenotype is as high as 0.01 % prevalent. High incidence of Bombay phenotype reported in Orissa of eastern India, among Kutia Kondh tribe. Another study from northwestern Orissa reported an average of 1 in 278 Bombay phenotype among Bhuyan tribal population.
Conclusion
As the patients with Bombay blood group cannot receive blood from ‘A’,’B’,’ AB’ and ‘O’ blood group. Not only proper blood grouping but also Cross matching should be performed because this type of blood group mimic O blood group and Reverse grouping and serum grouping should be performed for proper diagnosis.
References:
1. Ribhu Mishra 2019,Bombay blood group: Here’s why there is increased demand for this rare blood type 2:37.
2. Dhwani Jerajini 2016,Rarest blood group-all about bombay blood group,Pharmeasy
3. 2013,prevalence of bombay blood group.
4. How the rare blood group type discovered: bombay blood
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