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 Jk a (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 Jk a 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 Jk a 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 Jk a antigen presentation.