1. Two new RHD alleles with deletions spanning multiple exons.
- Author
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Matteocci A, Monge-Ruiz J, Stef M, Apraiz I, Herrera-Del-Val L, Mancuso T, Fennell K, Lopez M, Larizgoitia-Martin Y, Nespoli G, Rubia-Tejero M, Collaretti A, Pierelli L, and Ochoa-Garay G
- Subjects
- Alleles, High-Throughput Nucleotide Sequencing, Humans, Polymerase Chain Reaction, Rh-Hr Blood-Group System immunology, Sequence Deletion, Exons, Rh-Hr Blood-Group System blood, Rh-Hr Blood-Group System genetics
- Abstract
Background: The most common large-deletion RHD allele (RHD*01N.01) includes the entire coding sequence, intervening regions and untranslated regions. The rest of large-deletion RHD alleles reported to-date consist of single-exon deletions, such as RHD*01N.67 which includes exon 1., Materials and Methods: Samples from two donors with RhD-negative serology yielded unclear or inconclusive results when subject to confirmatory testing on RHD genotyping arrays. To determine their RHD genotypes, genomic DNA was analyzed with a combination of allele-specific PCR, long-range PCR, Sanger sequencing, and next-generation sequencing assays., Results: Allele-specific PCR failed to detect products for RHD exons 1 to 3 in one sample and RHD exons 1 to 5 in the other. A quantitative next-generation sequencing assay confirmed deletion of exons 1 to 3 and 1 to 5 respectively, and detected the absence of an RHD gene in trans in both samples. Long-range PCR and Sanger sequencing enabled identification of the breakpoints for both alleles. Both deletions start within the 5' Rhesus box (upstream of the identity region for the 1-to-3 deletion, downstream of it for the 1-to-5 deletion), and end within introns., Conclusions: Resolution of unclear or inconclusive results from targeted genotyping arrays often leads to the discovery of new alleles. The 5' Rhesus box may be a hot spot for genetic recombination events, such as the large deletions described in this report., (© 2020 AABB.)
- Published
- 2021
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