Small donor study links altered SLC14A1 transcripts with weak Jka antigen presentation

A study of 18 Chinese blood donors found differences in the structure and sequence of SLC14A1 messenger RNA between eight donors with normal Jka antigen presentation and 10 classified as having weak Jka, or Jk(a + w), by routine serological testing. The investigators reported associations between alternative splicing, transcript-level insertions and deletions, and weak presentation, but the small observational sample did not establish a definitive cause or validate a clinical test.

The donor study, published in PLOS One, recruited volunteers aged 25 to 55 at Shenzhen Blood Center between August 1, 2022, and May 31, 2025. Fresh blood samples were obtained with written informed consent under approval from the blood center’s research ethics committee. Each participant carried at least one JK*A allele, and PacBio long-read sequencing of genomic DNA was used to confirm the integrity of SLC14A1 and determine selected haplotypes.

For transcript analysis, the researchers extracted total RNA from the red-cell layer, where reticulocytes made SLC14A1 messenger RNA detectable. They synthesized complementary DNA, amplified the SLC14A1 open reading frame with two rounds of nested PCR, and used PacBio long-read sequencing to examine exon composition and sequence variation. Analysis of 4,895 valid reads from participant W7, for example, showed that multiple transcript patterns occurred within a single sample.

The investigators identified two potential exon regions not previously described, designated PER-4 and PER-5. PER-4 occurred in 19.16% of valid reads from donor N8, who showed normal Jka presentation, while PER-5 occurred in 12.17% of valid reads from donor W10, who showed weak presentation. Both events introduced frameshifts relative to the corresponding reference transcript variants. These were individual observations rather than group-level estimates of a new splicing pattern.

Donor W3 illustrated a different type of alteration. PER-9 through PER-11 were absent from all detected transcripts, although the corresponding regions were present in genomic DNA and no mutations were found at adjacent exon-intron junctions. The study located the Jka-associated position at nucleotide 838 in PER-11, so its complete absence was consistent with a contribution to W3’s weak phenotype. The finding applied to one individual and did not establish the proportion of normal PER-11-containing transcripts required to produce weak serological reactivity.

Patterns involving PER-6 and PER-7 also differed between the two phenotype groups. PER-6 appeared in more than 80% of valid reads from Jk(a + w) donors, compared with about 40% in donors with normal Jka presentation, and the authors reported statistically significant group differences. Skipping these potential exons could create a different start codon and a truncated SLC14A1 isoform. The authors proposed that transcript variation may influence antigen presentation, while calling for further work to determine the alternative start codon’s translation efficiency and compare the antigenic properties of the resulting protein isoforms.

Sequence differences were also detected in transcripts but not in matched genomic DNA. Examples included a G deletion in donor W2 and an A insertion in donor N7, both verified by Sanger sequencing. The researchers interpreted these observations as evidence of transcript-level errors, including insertions and deletions at or near the 130G/A single-nucleotide variant. In a focused analysis of six Jk(a + w) donors and four normal Jka donors, the frequency of these changes around 130A was higher than around 130G in every participant, regardless of phenotype.

For donor W6, 587 of 2,229 reads carrying 130A contained indels within the six-nucleotide region, an indel rate of 26.33%; the corresponding rate for 130G was 12.44%. Indel rates around both 130A and 130G were also reported to be significantly higher among Jk(a + w) donors than among normal Jka donors. The authors interpreted the group pattern as evidence of lower observed transcription fidelity in the weak-presentation group, rather than a direct demonstration that such errors caused the phenotype.

The researchers also tested whether reverse transcription or PCR amplification could explain the sequence changes. Products amplified directly from sequence-confirmed plasmids had fewer mismatches and indels than products obtained after in vitro-transcribed RNA underwent reverse transcription and PCR. This showed that some artifacts can arise during those procedures, but their rates in the six-nucleotide region were much lower than those observed in donor samples. The authors therefore judged the artifacts unlikely to account for the main findings while acknowledging the need for additional investigation.

The study was limited by its sample of 18 donors from one blood center, including only 10 participants with weak Jka presentation. It assessed transcript structure and sequence but did not directly measure the antigenic activity or expression of each predicted SLC14A1 protein isoform. The findings therefore identify transcript alterations as factors associated with weak Jka presentation, without showing that they alone cause the phenotype or establishing their usefulness in routine donor testing.

Subject of Research: SLC14A1 transcript structure and weak Jka antigen presentation in Chinese blood donors

Article Title: Alterations of SLC14A1 mRNA structure are frequently detected in weak Jk a presenting donors

Article References: Liang, S., Liang, Y., Wu, F., Liu, T., Sun, L., Luo, B., Wang, Y., Liu, Y., Feng, B., & Ren, J. (2026). Alterations of SLC14A1 mRNA structure are frequently detected in weak Jka presenting donors. PLOS One, 21(10), e0360437. https://doi.org/10.1371/journal.pone.0360437

Image Credits: AI Generated

DOI: 10.1371/journal.pone.0360437

Keywords: SLC14A1, Kidd blood group, Jka antigen, weak Jka phenotype, RNA splicing, transcription errors, PacBio sequencing, blood donors, transfusion medicine, Alterations, mRNA, structure