Indian hematologists presented the CRIB antigen, a new member of the Cromer blood-group system, at the 35th Regional Congress of the International Society of Blood Transfusion. The announcement renewed discussion about the need for rare-donor registries in genetically diverse populations.
The case that led to the discovery began in Karnataka last year. A 38-year-old woman from Kolar district, scheduled for elective cardiac surgery, appeared to be O Rh-positive, but routine cross-matching showed her blood was pan-reactive and incompatible with all standard donor units. Physicians collected samples from 20 relatives, yet none matched.
With no compatible blood available, clinicians sent her sample to the International Blood Group Reference Laboratory in the United Kingdom. Nine months of serological tests followed by molecular analysis revealed a previously unrecorded antigen in the Cromer system. Because the work originated in India and relied on Bengaluru laboratories, researchers named the antigen CRIB, an acronym that links the Cromer group with the city’s reputation as a technology hub.
While the investigation continued overseas, surgeons completed the woman’s cardiac procedure without transfusion, aided by blood-conservation techniques and family support. She recovered, and the laboratory findings reached Bengaluru earlier this year.
Specialists later determined that her red cells did not fit any standard ABO pattern. Although the woman is now labeled A-positive, every conventional donor unit still reacted with her serum.
The Blood Centre in Bangalore, working with the Indian Council of Medical Research, started a registry for rare blood types and plans to enroll any future CRIB carriers. Hematologists argued that such registries are necessary for patients whose uncommon serology complicates transfusion.
CRIB joined a small catalog of rare phenotypes that challenged transfusion practice. The Bombay phenotype, recorded in India in 1952, appears when people lack the precursor needed to form A and B antigens. Rh-null, found in Australia in 1961, is so scarce that about 50 people worldwide are known to possess it; because it lacks all Rh antigens, it can be given to recipients with rare Rh-negative types. Within the traditional ABO scheme, AB Rh-negative remains the rarest group, found in no more than one percent of the global population, whereas roughly 40 percent of people carry O Rh-positive, the most common type.
When the ABO system was described early in the 20th century, scientists considered it complete. CRIB, the forty-eighth antigen added since then, showed that human blood still holds surprises.
Written with the help of a news-analysis system.