Anti-PP₁P(k) (Tj(a)) Antibody in a Korean Female Patient with p Phenotype Confirmed by Genotyping

ABSTRACT

report a case of anti-PP₁P(k) (Tj(a)) alloantibody with p phenotype detected and confirmed in a 20-year-old Korean woman diagnosed with anemia during long-term rehabilitation treatment due to mental retardation. She did not have any transfusion history, except two exchange transfusions received 6 days after she was born. Her blood type was B, RhD+, and findings from antibody screening and identification tests showed strong reactivity (3+ to 4+) in all panel cells except in her autologous cells. Based on these results, we concluded that she had an alloantibody to a high-prevalence antigen. Anti-PP₁P(k) alloantibody with p phenotype was identified by additional serological tests in a foreign reference laboratory. To confirm the patient's p phenotype, polymerase chain reaction and sequencing of the A4GALT gene were performed on her blood sample. She was homozygous for c.301delG in the A4GALT gene, which finally confirmed that she had the anti-PP₁P(k) antibody with p phenotype. Fortunately, her anemia caused due to iron deficiency could be treated with iron supplementation without the need for any transfusion. However, it remains extremely difficult to find compatible red blood cells in such settings in Korea. Moreover, there has been very little research on the prevalence of the p phenotype in the Korean population. Therefore, additional research is needed on rare blood group antibodies and high-prevalence antigens, including anti-PP₁P(k) cases.