An update on the CD59 blood group system

Area of Science:

• Immunology
• Hematology
• Genetics

Background:

• The CD59 protein is a critical regulator of the complement system, preventing cell damage.
• CD59 deficiency has been associated with severe clinical manifestations.
• The CD59 blood group system (ISBT 35) previously comprised a single antigen.

Purpose of the Study:

• To update the understanding of the CD59 blood group system.
• To report on newly identified CD59 variant alleles and associated patient cases.
• To characterize the expression of a novel CD59 variant.

Main Methods:

• Literature review and case series analysis.
• Genetic analysis to identify variant alleles.
• Flow cytometry to assess protein expression on red blood cells.

Main Results:

• The number of reported patients with CD59 deficiency has increased from 10 to 14.
• All 14 patients presented with severe illness.
• A new variant allele of CD59 was identified in heterozygosity, expressed on red blood cells.

Conclusions:

• CD59 deficiency is consistently linked to severe disease.
• The identification of new alleles expands the known genetic landscape of CD59.
• Despite new alleles, the CD59 blood group system antigenically remains monomorphic.