The Indian (IN 023) blood group system: an update

Area of Science:

• Immunology
• Genetics
• Hematology

Background:

• The Indian (IN) blood group system, previously reviewed in 2011, is updated here.
• The system is characterized by specific antigens, antibodies, and genetic underpinnings.

Purpose of the Study:

• To detail the discovery and clinical significance of new antigens, antibodies, and genetics within the Indian blood group system.
• To provide an update on the IN blood group system since the last comprehensive review.

Main Methods:

• Review of recent discoveries and genetic analyses related to the Indian blood group system.
• Identification of high-prevalence antigens (HPAs) and associated genetic mutations.

Main Results:

• The Indian blood group system now comprises six antigens.
• Two new high-prevalence antigens, IN:005 (INRA) and IN:006 (INSL), have been identified.
• These antigens are located on CD44, a glycoprotein encoded by the CD44 gene.
• Absence of these HPAs is linked to homozygous missense mutations in the CD44 gene, observed in rare individuals from the Indian subcontinent.

Conclusions:

• The updated Indian blood group system includes novel HPAs with specific genetic mutations.
• Understanding these genetic variations is crucial for transfusion medicine, particularly in populations from the Indian subcontinent.