Bombay Blood Group: Blood Transfusion nightmare

The Bombay blood group is unique, unlike the common A, B, AB, and O types. It lacks the H antigen that’s usually present in all other blood types, which makes it fascinating for those who work in blood transfusion laboratories.

Historical Context to Bombay Blood Group

Back in 1952, something unexpected happened in Bombay (now Mumbai), India. Doctors at the Seth Gordhandas Sunderdas Medical College stumbled upon a medical mystery. Dr. Y.M. Bhende and his colleagues were surprised when they found patients whose blood group was very different from the known ABO blood types. This discovery led to the identification of a new blood group, which they named after the city where it was found – the Bombay blood group.

Geographical Prevalence

You might wonder, “How common is this blood type?” Well, it’s pretty rare. You might find about 1 in 10,000 people in India with this blood type.

But here’s the interesting part – it’s even rarer in other parts of the world. In Europe, for example, you’d have to search through about a million people to find someone with the Bombay blood type. Talk about a needle in a haystack!

 

The Science Behind the Rarity

The Bombay phenotype, as it’s scientifically known, is characterized by the absence of the H antigen on red blood cells. This is because of a point mutation in the FUT1 gene, which leads to an inactive enzyme.

 

What makes this blood type particularly challenging is that individuals with the Bombay phenotype can only receive blood from other Bombay blood type donors. This rarity and specificity make it difficult  for blood banks where such a patient may need blood transfusion.

 

Inheritance Pattern of Bombay Blood Group

The Bombay blood group is a rare genetic trait characterized by an “hh” genotype. This blood type occurs when an individual inherits two copies of a recessive allele, one from each parent. The inheritance pattern of the Bombay phenotype is particularly interesting, as it requires inheriting nonfunctional alleles of both the FUT1 and FUT2 genes.

 

FUT1 Gene

The FUT1 gene plays a role in determining blood type by encoding an enzyme called α1,2-fucosyltransferase. This enzyme is responsible for adding fucose to terminal galactose molecules on red blood cells, forming the H antigen. In individuals with the Bombay blood type, mutations in the FUT1 gene disrupt this process.

 

A and B Antigen Production

The H antigen serves as a precursor for A and B antigens in individuals with A, B, or AB blood groups. When the FUT1 gene is non-functional, it prevents the formation of the H antigen, consequently impacting A and B antigen expression. This genetic abnormality results in the absence of A, B, and H antigens on red blood cells in people with the Bombay blood type.

 

The lack of these antigens can lead to challenges in blood typing and transfusions. While Bombay blood may appear similar to type O in initial tests, it’s fundamentally different. This distinction is critical for proper medical care and highlights the importance of understanding rare blood types like the Bombay phenotype.

 

In some cases, mutations in the FUT1 gene may result in reduced rather than absent H antigen production, leading to a variant known as the para-Bombay phenotype. This further demonstrates the complexity of genetic factors influencing blood type and the potential for diverse presentations within rare blood group categories.

 

Misdiagnosis as O Blood Group

Here’s where things get tricky. The Bombay blood group is often confused with type O, leading to potential misdiagnosis. Why? It’s all about those antigens!

Standard or routine blood grouping tests typically only look for A and B antigens or their absence. Since the Bombay blood group lacks these, it can appear identical to type O at first glance. But there’s a peculiar  difference – the H antigen.

• Type O blood: Has the H antigen
• Bombay blood group: Lacks the H antigen

This distinction is super important because it affects blood transfusion compatibility. Someone with the Bombay blood group can’t receive blood from A, B, AB, or even O types. They can only accept blood from other Bombay blood group donors.

 

To correctly identify the Bombay phenotype, laboratory scientists need to use a special reagent called anti-H lectin. This test looks specifically for the H antigen, which is the key to distinguishing between Bombay and type O blood.

The confusion between Bombay and type O blood isn’t just a minor mix-up. It can have serious consequences in medical situations. If someone with the Bombay blood group receives type O blood (or any other type), it can trigger a dangerous hemolytic reaction. That’s why it’s important for healthcare providers to be aware of this rare blood type and test for it when necessary.

Implications for Blood Transfusions

Donation Compatibility

Individuals with the Bombay blood group can be universal donors for red blood cells, but with a catch. While their red cells lack A, B, and H antigens, making them compatible with all other blood types, their plasma contains anti-A, anti-B, and anti-H antibodies. This means Bombay blood can only be safely donated as packed red cells after removing the plasma.

 

For plasma donation, however, Bombay blood group individuals face significant restrictions. Their plasma, rich in anti-H antibodies, is only compatible with other Bombay blood type recipients. This limitation highlights the importance of identifying and registering Bombay blood donors for potential emergencies.

Receiving Blood

They can only receive blood from other Bombay phenotype donors. Bombay blood contains anti-H antibodies, which will attack any red blood cells with the H antigen – that’s pretty much all other blood types!

 

This creates a significant challenge for patients with the Bombay phenotype. Finding compatible blood can be like searching for a needle in a haystack, especially in emergency situations. It’s not just about matching ABO types; it’s about finding that rare Bombay match.

 

Risk of Hemolytic Transfusion Reactions

The presence of anti-H antibodies in Bombay blood makes transfusion with non-compatible blood extremely dangerous. If a Bombay blood group individual receives blood from any other type, including O negative (usually considered the universal donor), it can trigger a severe hemolytic transfusion reaction.

In such a reaction, the anti-H antibodies attack the transfused red blood cells, causing them to rupture. This can lead to serious complications like:

• Kidney failure
• Shock
• Disseminated intravascular coagulation (DIC)

These reactions can be life-threatening, underscoring the critical importance of accurate blood typing and cross-matching for patients with rare blood phenotypes like Bombay.

Management Strategies for Bombay blood group

Given the scarcity of compatible blood, healthcare providers have developed several strategies to manage patients with the Bombay blood group:

1. Autologous Blood Transfusion: This involves collecting and storing the patient’s own blood for future use, which can be particularly useful in planned surgeries or pregnancies.
2. Normovolemic Hemodilution: In non-emergency situations, this technique can help reduce the need for transfusions by temporarily diluting the patient’s blood.
3. Family Screening: Testing family members, especially siblings, increases the chances of finding compatible donors.
4. Rare Blood Registries: National and international databases of rare blood donors are important for locating compatible blood in emergencies.

Some advancement in Bombay transfusion: Turning Universal Group O to Bombay Group

Some research has shown promising developments in blood type conversion. Scientists have discovered an enzyme (FucOB) from the bacterium Akkermansia muciniphila that can potentially convert universal O type blood into the Bombay type. This breakthrough could revolutionize blood transfusion management for Bombay phenotype patients by creating compatible red cells in vitro.

Diagnostic Challenges in Identifying the Bombay Blood Group

Standard ABO Blood Grouping Tests: A Potential Pitfall

When it comes to identifying the Bombay blood group, standard ABO blood typing tests can be misleading. These tests typically look for the presence of A and B antigens on red blood cells. The problem? Bombay blood lacks these antigens, just like type O blood. This similarity can lead to a dangerous misdiagnosis.

 

Here’s why standard tests might miss the mark:

• Forward grouping (testing red cells with anti-A and anti-B) shows no reaction, mimicking type O.
• Reverse grouping (testing serum against known A and B cells) may show pan-agglutination, which can be misinterpreted.

This is where things get tricky. A person with the Bombay phenotype could be mistakenly typed as O, potentially leading to a life-threatening situation if they receive incompatible blood.

The Role of Anti-H Lectin

Anti-H lectin is the deal breaker. This special test is necessary for correctly identifying the Bombay blood group. Here’s how it works:

1. Anti-H lectin specifically targets the H antigen on red blood cells.
2. In normal ABO blood types, including O, the test will show agglutination.
3. For Bombay blood, there’s no reaction because the H antigen is absent.

 

This simple yet powerful test is the key to distinguishing between Bombay and type O blood. It’s not just a nice-to-have; it’s a must-do when there’s any suspicion of a rare blood type.

Comprehensive Diagnostic Approach to Bombay Group Identification.

But wait, there’s more! Confirming the Bombay phenotype often involves a multi-step process:

• Saliva testing for ABH antigens (Bombay individuals lack these in their saliva too)
• Adsorption-elution studies to detect any trace amounts of H antigen
• Genetic testing to identify mutations in the FUT1 gene

 

These additional tests help create a complete picture, ensuring accurate diagnosis and proper patient care.

The Importance of Accurate Identification

Remember, proper identification isn’t just about satisfying scientific curiosity. For someone with the Bombay blood group, it can be a matter of life and death. That’s why it’s important for healthcare providers especially those in transfusion medicine to be aware of this rare blood type and know when to reach for that anti-H lectin test.

In cases where Bombay blood is confirmed, special management strategies may be necessary, such as acute normovolemic hemodilution for surgical patients, to ensure safe transfusion practices.

 

Clinical and Therapeutic Management of the Bombay Blood Group

Family Screening

For patients diagnosed with the Bombay blood group, family screening is a critical step in their clinical management. Here’s why it’s so important:

• Genetic link: The Bombay phenotype is inherited, so family members are more likely to have it too.
• Potential donors: Siblings have a 25% chance of sharing the same blood type, making them valuable potential donors.
• Proactive care: Identifying family members with the Bombay phenotype allows for better preparation in case of future medical needs.

 

The screening process is straightforward but essential:

1. Start with immediate family (siblings, parents, children)
2. Extend to extended family if needed
3. Use the anti-H lectin test to accurately identify the phenotype

When this is done, a network of potential donors for the patient may have been built. This can be a lifesaver in emergency situations where compatible blood is needed quickly.

National Rare Blood Group Registries

National rare blood group registries play an important role in managing patients with the Bombay phenotype. These registries are essential for several reasons:

• Quick access: In emergencies, these registries can quickly locate compatible donors.
• Wider reach: They connect patients with rare blood types to potential donors across the country or even internationally.
• Better preparedness: Hospitals can use these registries to plan for surgeries or other procedures requiring blood transfusions.

 

Some key features of these registries:

• Detailed donor information, including blood type and contact details
• Regular updates to ensure information is current
• Coordination with blood banks and hospitals for efficient distribution

 

Countries with well-established rare blood group registries have seen improved outcomes for patients with rare blood types. These registries don’t just list donors; they’re a lifeline connecting patients to the specific blood they need.

For transfusion medicine professionals, knowing how to access and utilize these registries is important. It’s not just about knowing they exist; it’s about integrating them into emergency protocols and treatment plans.

 

Pre-operative Preparation

For patients with the Bombay blood group undergoing elective surgeries, proper pre-operative preparation is essential. This may include:

• Arranging autologous blood donation before the surgery
• Administering erythropoietin, intravenous iron, and folic acid to boost red blood cell production
• Considering minimally invasive surgical techniques to reduce blood loss

 

These strategies can significantly reduce the need for transfusions during and after surgery, minimizing the risk of complications.

Transfusion Management

When transfusion is necessary for Bombay blood group patients, specific protocols must be followed:

• Use only autologous or Bombay phenotype red blood cells
• Implement strict cross-matching procedures to ensure compatibility
• Coordinate closely with the blood bank and clinical team to manage risks and benefits

In some cases, novel approaches such as enzymatic conversion of universal O type blood to Bombay type may provide additional options for transfusion.

Patient Education and Support

Proper education and support for Bombay blood group patients are crucial:

• Provide patients with an antibody card and detailed letter explaining their blood type and transfusion requirements
• Counsel patients on the importance of informing healthcare providers about their rare blood type
• Encourage patients to participate in registries and consider becoming regular blood donors if eligible

By implementing these comprehensive management strategies, healthcare providers can ensure the best possible care for patients with the Bombay blood group, addressing both their immediate and long-term needs.

 

Conclusion

The Bombay blood group isn’t just a medical curiosity – it’s a prime example of why understanding rare blood types is important. For healthcare professionals, being aware of this unique phenotype can mean the difference between life and death in emergency situations.

The key takeaway is clear: in the world of hematology and blood transfusion, what’s rare is precious. We must be prepared and ensure that even patients with the rarest blood types receive the care they need, when they need it most.