Genetic variation of the HNA‐3a encoding gene

BACKGROUND: Antibodies against the human neutrophil alloantigen‐3a (HNA‐3a) play an important role in transfusion‐related acute lung injury. The HNA‐3a and ‐3b alloantigens result from a single‐nucleotide exchange in the choline transporter‐like protein 2 gene (CTL2). We sought for additional polymorphisms that might impair antibody binding to or genotyping of the HNA‐3a or ‐3b antigens. STUDY DESIGN AND METHODS: CTL2‐specific complementary DNA (cDNA) fragments were generated from 67 unrelated blood donors followed by DNA sequencing. Polymerase chain reaction with sequence‐specific primers (PCR‐SSP) was used to test a higher number of donors for relevant new single‐nucleotide polymorphisms (SNPs). The granulocyte agglutination test recommended for HNA‐3a antibody detection was performed to check HNA‐3a antibody binding to the products of the CTL‐2 gene variants. RESULTS: Two new missense mutations were demonstrated in the CTL2 cDNA: a 537C>T * exchange leading to a Leu153Phe amino acid substitution and 988C>T variation predicting Thr301Met change. The inherited 537T variant is located in HNA‐3a allele results impaired granulocyte agglutination by four of 14 antibodies tested while 988T remains nearly unaffected. CONCLUSIONS: The Leu153Phe exchange next to the HNA‐3a/b defining amino acid position can impede the binding of HNA‐3a alloantibodies. The HNA‐3a genotyping by PCR‐SSP might produce misleading results in HNA‐3ab heterozygous individuals with the additional CTL2‐537T variation of the HNA‐3a antigen. These findings must account for the development of new screening assays.