ABO Genotyping and Resolution of A and B Discrepancies

ABO blood grouping is crucial for safe blood transfusion. Since the cloning of the ABO gene in 1990,[21] progress has been made in the structural and functional analyses of the ABO genes and A and B transferases at the molecular level. A proportion of blood donors and patients who historically have been typed as group O are now being recognized as group A or group B with the use of monoclonal antibodies capable of detecting small amounts of the immunodomi-nant carbohydrate responsible for A or B specificity. A typing result that differs from the historical record often results in time-consuming analyses. Because the bases of many weak subgroups of A and B are associated with altered transferase genes, PCR-based assays can be used to define the transferase gene and thus the ABO group.[22] A majority of the mutations are nucleotide substitutions, resulting in amino acid substitutions or a single nucleotide deletion/insertion, and correlate well with the presence of specific subgroup alleles.

Table 2 Molecular events that give rise to blood group antigens and phenotypes

Gene conversion or recombination events (MNs, Rh, Ch/Rg blood group systems) Duplication of an exon (Gerbich)

Deletion of a gene, exon, or nucleotide(s) (ABO, Rh, MNS,

Kel, Duffy, Dombrock)

Insertion of a nucleotide(s) (Rh, Colton)

Single nucleotide substitutions (most blood group systems)

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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