In a discovery hailed as a watershed moment in transfusion medicine, scientists in India and the UK have jointly identified a new and extraordinarily rare human blood group named CRIB.
Found in a 38-year-old woman from Kolar, Karnataka, this is currently the only known instance of the blood group in the world. Her case baffled doctors when none of the standard blood units, not even those of her close relatives, matched her profile, forcing a complex cardiac surgery to be conducted without a transfusion.
This breakthrough, announced at the 35th Regional Congress of the International Society of Blood Transfusion (ISBT) in Milan, Italy, opens up new frontiers in prenatal care, rare donor registries, and global transfusion protocols. “This is a once-in-a-century discovery. It redefines what we know about human blood,” said Dr Ankit Mathur of Rotary Bangalore TTK Blood Centre, speaking to The Hindu.
The Discovery That Defied All Medical Expectations
The patient was initially admitted to a hospital in Kolar for cardiac surgery. Her blood type was O Rh+, the most common in the world. However, when crossmatching tests were conducted, not a single unit of O-positive blood was found to be compatible.
Even 20 of her family members, tested in the hope of finding a match, turned out incompatible, a phenomenon almost unheard of in routine transfusion practice. Her case was referred to the Advanced Immunohematology Reference Laboratory at the Rotary Bangalore TTK Blood Centre.
“We observed panreactivity, which means her blood was incompatible with every known donor sample,” said Dr Mathur, in a statement quoted by the Indian Express. This reaction indicated the presence of an unidentified antigen that made transfusion nearly impossible. Her surgery had to proceed without a blood transfusion, an extremely high-risk decision that doctors say was only made possible due to meticulous planning.
What Is The CRIB Blood Group?
The CRIB blood group is now classified under the Cromer (CR) blood group system, one of 47 internationally recognized blood group systems. CRIB stands for Cromer India Bangalore, acknowledging both its antigen system and the location of the discovery. It is also listed under the Indian Rare Antigen (INRA) system, recognized by the ISBT in 2022.
What makes CRIB exceptionally rare is the absence of a high-prevalence antigen found in almost every human being. “There is no match anywhere in the world for this patient. Her red cells lack an antigen that over 99.9% of the population has,” explained Dr C Shivaram, Consultant and Head of Transfusion Medicine at Manipal Hospital, in an interview with Deccan Herald.
As a result, only individuals who share this exact rare absence can donate blood to someone with the CRIB group, and at present, only one such individual is known: the woman herself.
Why Is CRIB The Rarest Blood Group?
CRIB is considered the rarest blood group because no other known human has been identified with it. This makes it even rarer than the “Rh-null” or “Golden Blood,” of which around 50 individuals are known globally. The CRIB antigen is entirely absent from all known donor records, including international blood banks, making this case truly one of a kind.
Another factor that amplifies its rarity is that the patient developed this unique blood profile despite never having undergone a transfusion or pregnancy, common triggers for the development of rare antibodies.
Her blood naturally lacked a high-prevalence antigen that 99.9% of the world’s population possesses, leading to panreactivity with every tested sample. “We’re dealing with something beyond textbook medicine,” said Dr Mathur to the Times of India.
Understanding The Cromer Blood Group System
While the ABO and Rh systems are widely known, the Cromer system is a lesser-known yet clinically significant blood group system, defined by glycoproteins present on the red blood cell membrane. Antibodies against Cromer antigens are rare but dangerous, especially during pregnancy or transfusion.
Cromer-related incompatibility typically arises from previous transfusions or pregnancies. However, in this case, the Kolar woman had never received a transfusion. The unique reactivity of her blood baffled researchers and hinted at an entirely novel antigen.
“This variant had not been documented anywhere, not even in the International Blood Group Reference Laboratory in Bristol,” noted Dr Mathur. Ten months of global collaboration and molecular testing confirmed it was indeed a new antigen, now officially named CRIB.
Implications For Global Medicine And Prenatal Care
The CRIB discovery could transform the landscape of critical care, particularly in complex surgeries and maternal-fetal medicine. If a fetus inherits an antigen the mother lacks (or vice versa), it can lead to hemolytic disease of the newborn, a condition where antibodies attack the baby’s red blood cells. Identifying rare blood groups like CRIB in time can prevent fatal complications.
Moreover, this breakthrough shows the urgent need for rare blood donor registries. The Rotary Bangalore TTK Blood Centre has already initiated a Rare Donor Registry, supported by the Karnataka State Blood Transfusion Council, the Indian Council of Medical Research (ICMR), and the International Society of Blood Transfusion.
“Our rare donor database has played a vital role in managing unique cases like Rh-null and Inb-negative. CRIB is another feather in the cap,” said Dr Mathur, as reported by the Times of India.
Also Read: Lack Of This Vitamin Can Make You Feel Suicidal
India’s Growing Role In Rare Blood Research
India is fast becoming a hub for rare blood antigen research. With over 1.4 billion people, its genetic diversity has proven invaluable in uncovering rare blood group variations. The discovery of CRIB further solidifies the country’s leadership in transfusion science.
Already, Indian researchers have contributed significantly to the study of extremely rare blood types like D–, Rh-null, and In b-negative. “The identification of CRIB showcases India’s advanced research infrastructure and global collaboration,” stated Dr Rakesh Sinha, senior haematologist at ICMR, in a panel discussion at ISBT Milan.
India’s strategic partnerships with global laboratories, such as the IBGRL in the UK, have accelerated these breakthroughs, bringing rare cases into the limelight.
A New Chapter In Human Blood Science
The discovery of the CRIB blood group is not just a scientific novelty; it is a paradigm shift in how we understand blood compatibility, rare antigens, and global healthcare collaboration. With only one individual identified with this blood type, it remains the rarest blood group on the planet today.
As transfusion science evolves, such findings underscore the importance of investing in research, rare donor registries, and early screening systems. From a quiet district in Karnataka, a global medical milestone has emerged, reminding the world that sometimes, even the most revolutionary breakthroughs begin with one patient.
Images: Google Images
Sources: Economic Times, NDTV, New Indian Express
Find the blogger: Katyayani Joshi
This post is tagged under: rare blood group, CRIB blood group, transfusion medicine, Cromer antigen, rare donor registry, Kolar woman blood group, India medical breakthrough, prenatal diagnostics, global health innovation, ISBT Milan 2025
Disclaimer: We do not own the rights or copyrights to any of the images used; these have been sourced from Google. If you are the owner and require credits or removal, please feel free to email us.
Other Recommendations:
New Study Says Those Born Between 2008-2017 May Develop This Cancer Type
