An update on the H blood group system.

Area of Science:

• Immunology
• Genetics
• Biochemistry

Background:

• The H blood group system (ISBT system 18) is defined by the H antigen, a terminal fucose residue.
• H antigen is crucial for expressing other blood group antigens, particularly ABO.
• Synthesis of H antigen on red blood cells involves FUT1, while FUT2 is involved in secretions.

Purpose of the Study:

• To update knowledge on the H blood group system.
• To report newly identified FUT1 alleles and their associated phenotypes.

Main Methods:

• Analysis of FUT1 gene sequences.
• Phenotypic characterization of individuals with H blood group system variations.

Main Results:

• Identification of 11 new FUT1 null alleles.
• Eight alleles are causative for the H- phenotype (Bombay, Oh).
• Three alleles are associated with para-Bombay cases, and five with a weak H phenotype (para-Bombay, H+w).

Conclusions:

• The FUT1 gene exhibits significant allelic diversity.
• These new alleles contribute to a deeper understanding of H antigen expression and related phenotypes.
• This research refines the genetic basis of the Bombay and para-Bombay phenotypes.