Alterations of SLC14A1 mRNA structure are frequently detected in weak Jka presenting donors

RNA structural changes caused by mis-splicing or transcription errors may affect antigenic features of cell surface proteins. They are especially noteworthy in the field of blood transfusion where the discrepancy between DNA-based molecular testing and serological blood typing are often encountered in clinical practice and lead to mismatched blood transfusion. In the Kidd (JK) blood group system weak Jka (Jk(a + w)) phenotype is usually missed in routine serological tests and causes delayed hemolytic transfusion reactions. However molecular bases underlying Jk(a + w) phenotype are still not clear although plentiful genomic DNA-based studies have been conducted. In this study, we used PacBio long-read sequencing to characterize open reading frame (ORF) region of SLC14A1 mRNA obtained from reticulocytes of 18 blood donors possessing JK*A alleles. Among them, 8 donors were determined as normal Jka antigen presentation and 10 donors showed Jk(a + w) phenotype in routine serological tests. We found that Jk(a + w) subjects demonstrated different exon combination patterns compared to those individuals presenting normal Jka antigens, implying the resulted SLC14A1 protein isoforms could make different contributions to the formation of the JK antigenicity. Moreover, exon skipping and exon inclusion that were frequently found in Jk(a + w) individuals could induce frameshift mutations. In addition, high levels of nucleotide insertions or deletions (indels) at 130A position were detected in the transcripts of Jk(a + w) individuals. Technical artifacts were examined using synthesized RNA templates and the results suggested that artifacts generated in reverse transcription and PCR amplification (RT-PCR) processes were unlikely the causes of these observations. All the results indicate that SLC14A1 RNA splicing and transcription fidelity play crucial roles in determining Jka antigen presentation.