Doctors in the southern Indian state of Karnataka have, for the first time in the world, identified a unique blood group with a previously unknown antigen. The discovery was made while preparing for a planned heart surgery on a 38-year-old woman from Kolar district, according to The New Indian Express.

The woman was initially classified as having O Rh-positive blood — the most common blood type. However, none of the standard O-positive blood samples proved compatible for transfusion.

According to Dr. Ankit Mathur, a surgeon at the Kolar clinic, the patient’s blood was found to be “pan-reactive” — incompatible with all available test samples. Even among 20 of the woman’s relatives, no suitable donor could be found.

The surgery was ultimately carried out successfully without a transfusion, but the unusual nature of the case drew the attention of medical specialists. Blood samples were sent to the International Blood Group Reference Laboratory in Bristol, UK, and the Blood Center in Bangalore. After ten months of molecular research, scientists confirmed the existence of a new antigen, now named CRIB. The exceptional clinical case was also presented at the 35th Regional Congress of the International Society of Blood Transfusion (ISBT) in June 2025 in Milan.

The Bangalore Blood Center and the Indian Council of Medical Research have already begun forming a registry of rare blood donors, including potential carriers of the newly identified CRIB antigen. Some experts believe the mutation may have arisen due to consanguineous marriages, which are still practiced in certain regions of India.