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- Jöud, Magnus
(författare)
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Bioinformatic studies of genetic variation at known, novel and candidate blood group loci
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Access to compatible blood for transfusion is a prerequisite for modern health care. The compatibility is limited by the presence of antibodies to blood group antigens, polymorphic protein and carbohydrate structures, on the surface of the red blood cell. Blood group antigens arise from genetic variation in the genes underlying their expression. Knowledge of these genes and their variation can facilitate the provision of compatible blood.The overall aim of the thesis, comprising four papers, was to study the genetic variation at loci underlying human blood group systems and antigens, using bioinformatic methods. In Paper I, the genetic background of the Vel– blood group phenotype was elucidated. In Paper II, the genetic variants regulating the variable expression of the Vel blood group antigen was studied. In Paper III, whole genome sequencing (WGS) data from the 1000 Genomes project were used to create a database of all alleles in known blood group-related genes and to predict the presence of novel blood group antigens. Finally, in Paper IV, human glycosyltransferase genes expressed in erythroid tissue were identified and the potential for candidate carbohydrate-based blood group systems was predicted.Using SNP array data from Vel-phenotyped blood donors, including members of two families, a 17-base-pair deletion in the previously uncharacterized but evolutionary conserved gene SMIM1 was found to cause the Vel− bloodgroup phenotype. In Vel+ blood donors from different populations, two polymorphisms in intron 1 of SMIM1, rs1175550, and, to a lesser extent, rs143702418, were found to affect the expression of the Vel blood group antigen. In WGS data from the 1000 Genomes project, a large number of previously unreported blood group gene-related alleles were found and compiled into a database, Erythrogene. Among all identified genetic variants, 357 were non-synonymous and predicted to occur on the extracellular portion of blood group-carrying proteins and may represent novel or modified blood group antigens. In the human genome, 244 expressed glycosyltransferase genes were identified, 30 of which were predicted to have properties similar to known genes in carbohydrate-based blood group systems.The use of bioinformatic methods in the search of genetic variation underlying blood group systems and antigens was successful. The benefits of utilizing publicly available genotyping data in studies of blood groups are highlighted.
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| 2. |
- Jöud, Magnus, et al.
(författare)
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Identification of human glycosyltransferase genes expressed in erythroid cells predicts potential carbohydrate blood group loci
- 2018
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Glycans are biologically important structures synthesised by glycosyltransferase (GT) enzymes. Disruptive genetic null variants in GT genes can lead to serious illness but benign phenotypes are also seen, including antigenic differences on the red blood cell (RBC) surface, giving rise to blood groups. To characterise known and potential carbohydrate blood group antigens without a known underlying gene, we searched public databases for human GT loci and investigated their variation in the 1000 Genomes Project (1000 G). We found 244 GT genes, distributed over 44 families. All but four GT genes had missense variants or other variants predicted to alter the amino acid sequence, and 149 GT genes (61%) had variants expected to cause null alleles, often associated with antigen-negative blood group phenotypes. In RNA-Seq data generated from erythroid cells, 155 GT genes were expressed at a transcript level comparable to, or higher than, known carbohydrate blood group loci. Filtering for GT genes predicted to cause a benign phenotype, a set of 30 genes remained, 16 of which had variants in 1000 G expected to result in null alleles. Our results identify potential blood group loci and could serve as a basis for characterisation of the genetic background underlying carbohydrate RBC antigens.
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