A Very Rare Case with Particular H-deficient Phenotypes.

Area of Science:

• Hematology
• Genetics
• Immunology

Background:

• Rare blood groups like Bombay, Para-Bombay, and H-deficient phenotypes are characterized by absent or deficient H antigen.
• Accurate blood group determination is crucial for transfusion medicine and understanding genetic variations.

Purpose of the Study:

• To investigate and characterize a rare H-deficient secretor phenotype (para-Bombay) in a patient presenting with discrepant ABO blood typing results.
• To analyze the genetic basis and serological characteristics of this variant H-deficient phenotype.

Main Methods:

• Serological testing including ABO blood typing (forward and reverse grouping), saliva secretion tests, and Lewis phenotyping.
• Pedigree studies to assess familial inheritance patterns.
• DNA sequencing of ABO and FUT1 genes to identify causative mutations.

Main Results:

• The patient exhibited a variant H-deficient secretor phenotype (para-Bombay) with absent H antigen on red blood cells.
• Conflicting results were observed in saliva tests using different anti-H reagents, indicating H substances were present with one reagent and absent with another.
• Genetic analysis revealed the patient's ABO genotype as A102/O01 (261delG and 467C>T heterozygote) and FUT1 mutations (328G/A and 658C/T).
• The patient's Lewis phenotype was Le(a-b+) and anti-HI antibodies were detected in her serum.

Conclusions:

• The case highlights a unique variant of the para-Bombay phenotype presenting with H antigen deficiency and contradictory saliva test outcomes.
• The findings underscore the importance of using multiple reagents and comprehensive genetic analysis for accurate identification of rare blood groups.
• This variant H-deficient phenotype has implications for blood transfusion compatibility and understanding H antigen expression regulation.