RH genotyping by next-generation sequencing

Next-generation sequencing (NGS) has revolutionized personalized medicine and is being applied routinely in clinical diagnostics for oncology, congenital diseases, microbiology, and others. Transfusion medicine is not the exception. With 45 blood groups, more than 300 antigens and close to 2,000 known alleles, NGS provides high-resolution capabilities for detection of genetic changes and identification of new variants. Particularly, the Rh system paralog genes, RHD and RHCE, are recognized as a challenge due to phasing of single nucleotide variants (SNVs), hybrid rearrangements, and conversion events. NGS approaches such as whole genome, exome and targeted hybridization capture sequencing have proved successful in correctly describing these genetic changes in the Rh system and identifying new alleles. Moreover, improvements in quality during the last few years and access to long read NGS technology promise to catapult the resolution of RH hybrid rearrangement and phasing. Remaining challenges are related to data storage, bioinformatic capacity, and development of appropriate pipelines. The ethical use and safeguarding of patient and donor genetic data also warrant critical consideration. Overall, these highly discriminatory sequencing methodologies provide precision for blood antigen determination, increasingly lower costs and faster turnaround time. Their implementation as routine methods for blood genotyping is a future promise in transfusion medicine and must be accompanied by clear delineations of legal and ethical use of the data.