Blood Podcast Bonus Episode: What Is a Blood Group?

Published March 31, 2025
Host: Dr. Erica Wood (Associate Editor, Blood; Monash University, Melbourne)
Guest: Nicole Thornton (Head, International Blood Group Reference Laboratory, Bristol, UK)

Episode Overview

This bonus episode dives deep into the groundbreaking research published in Blood on the definition and molecular basis of the rare inherited ANWJ negative blood group. Dr. Erica Wood interviews lead author Nicole Thornton, exploring both the challenges of identifying the genetic underpinnings of rare blood groups and the significant clinical implications for transfusion medicine.

Key Discussion Points & Insights

1. Background and Significance of the Study

• Discovery and Complexity:

  • Nicole Thornton’s team has been working to identify the gene responsible for the ANWJ antigen, a challenge dating back nearly 20 years.
  • The ANWJ antigen was first identified in the early 1970s, but its molecular genetics remained a mystery until this work.
  • This discovery not only solves a longstanding puzzle but opens doors for further hematological research.

  • “ANWJ has been a long standing mystery... The gene responsible for encoding that antigen hasn’t been known until we set to work on it.” — Nicole Thornton [03:13]

• Clinical Relevance:

  • The presence of antibodies against the ANWJ antigen can cause hemolytic transfusion reactions, making safe transfusions difficult for affected patients.
  • The genetic identification of the antigen therefore has immediate clinical importance.

  • “The antibody involved does cause hemolytic transfusion reactions. So we wanted to get an answer to this one, especially because it would have a patient impact.” — Nicole Thornton [03:47]

2. Major Findings of the Paper

• Genetic Basis of ANWJ Negative Blood Group:

  • The research team identified deletions in the MAL gene as the cause of the absence of the ANWJ antigen.
  • They also noted that being ANWJ negative can occur by two distinct mechanisms: true genetic lack (via MAL deletion) and a “suppression effect” where antigen expression is reduced, often in hematologic malignancies.

  • “There is more than one way to be an ANWJ negative individual. There is the genetic way, which we’ve discovered, but there’s also another way and that’s a suppression effect.” — Nicole Thornton [05:16]

• Suppression of Antigen Expression:

  • The suppression type, associated with certain blood cancers, results in reduced or absent antigen expression, complicating diagnosis and treatment:

  • “The suppression type... is generally when a patient has sort of a hematological malignancy. We see now that the ANWJ antigen is reduced or very, very much suppressed.” — Nicole Thornton [07:58]

3. Implications for Research and Medicine

• Impact on Blood Group Genetics and Transfusion Medicine:

  • The newly clarified genetic basis will improve genotyping accuracy, guiding safer transfusion strategies.
  • The work sets a foundation for studying suppression phenomena, with potential implications for cancer biology and therapy:

  • “We know that in this suppression type we see hemolytic transfusion reactions occurring... it means that this molecule has an important role. Why is it suppressed in these situations? Can we maybe exploit that information for targeted therapies in these malignant states?” — Nicole Thornton [08:35]

• Wider Scientific Value:

  • The discovery enables broader investigation into the function of the MAL protein in hematological diseases and potentially other tissues.

  • “We’re describing a molecule that we don’t know a lot about the function of it. And now having a blood group marker may be able to help other areas in hematology also look at what this molecule is doing in certain disease states.” — Nicole Thornton [04:23]

4. Defining a Blood Group & the Rigorous Validation Process

• What Constitutes a Blood Group:
  • Multiple lines of evidence are required to define a blood group, including genetic, serological, and clinical proof.
  • The international working party (International Society of Blood Transfusions) reviews and rigorously challenges each proposal to ensure accuracy.

  • “It goes through a very stringent process when it comes to ratification... we do make sure that we have proven this in several different ways, not just one. Which is the approach we took in this study…” — Nicole Thornton [10:31]

  • “The rule of thumb is they don’t exist until there’s an antibody that defines them... and that was the case for us with ANWJ.” — Nicole Thornton [11:31]

5. On the Function of the MAL Protein

• “The function of it in the red cell is very unknown. But the name itself is myelin and lymphocyte protein, so that’s obviously been known to be important in lymphocytes… we find that a lot of the molecules in red cells, we don’t know the biological function. But what we do know is when we have these natural knockouts... then that tells us a lot.” — Nicole Thornton [12:43]

6. The Power of Collaboration

• The study’s success depended on global collaboration, with patient samples sent from around the world.

• “It takes bringing all of those samples together to be able to study them in the way that we did. And that really does rely on quite an amazing international collaboration.” — Nicole Thornton [06:58]

Notable Quotes & Memorable Moments

• On Persistence in Science:
  “It did take us quite a while because it’s a really complicated molecule... it takes an awful, awful lot of work to actually get enough evidence to prove a new blood group.” — Nicole Thornton [02:48]

• On Future Blood Group Discoveries:
  “There are some antigens that are still unknown, we don’t know the genetic basis of. But it’s not just the known antigens. We’re going to discover new ones.” — Nicole Thornton [05:54]

• On the Gravity of Blood Group Definition:
  “The consequences of it being wrong and a blood group being ratified incorrectly could mean that then genotyping platforms are going to predict the wrong blood group phenotype.” — Nicole Thornton [10:12]

Key Timestamps

• 00:25–01:11: Dr. Erica Wood introduces Nicole Thornton and the paper’s background
• 01:11–06:58: Thornton discusses the path to discovering the genetic basis, clinical significance, and the collaborative process
• 07:26–09:17: Discussion on genetic and suppression mechanisms for ANWJ negativity and their implications
• 09:49–12:11: Defining a blood group and the robust validation process
• 12:11–13:48: Exploration of the potential biological function of the MAL protein
• 13:48–14:44: Closing remarks and reflections on the impact of the research

Conclusion

This episode offers a rare view into the scientific detective work behind defining a blood group, highlighting the rigor, collaboration, and patient impact that drive advances in transfusion medicine. Listeners come away with a deeper appreciation for the complexities of blood group genetics, the vital importance of accurate diagnosis for patient care, and the exciting frontiers still ahead in hematology.