Background: The paucity of appropriate reagents for serologic typing of the Diego blood group has hindered the identification of the rare Di(b-) blood donors needed to transfuse a Dib antigen-negative patient who presented with anti-Dib. Development of an alternative Di typing approach as a supplement to the current serologic typing method is an important and necessary goal.
Study design and methods: DI1 and DI2 alleles result from a single C to T substitution at nucleotide 2561 in exon 19 of the human anion exchanger gene causing a proline (DI1) to leucine (DI2) change at amino acid position 854. Allele-specific primers were designed to specifically amplify the DI1 and DI2 alleles using a PCR-based assay system.
Results: A PCR sequence-specific primer (SSP) method for Di genotyping was developed, and the specificity and reproducibility of the method were assessed in a blind control study using serologic tests, family segregation, and DNA sequencing analyses. A total of 1,766 DNA samples from unrelated blood donors were typed for DI1 and DI2 alleles and a single Di(b-) donor was identified. The frequency of DI1 and DI2 alleles among Chinese blood donors was 0.0357 and 0.9643, respectively.
Conclusion: A simple, accurate, and inexpensive DNA-based PCR-SSP method was established for Di genotyping. The typing results can be visualized on a single photograph within 3 hours, making this reliable method suitable for large-scale typing of potential blood donors without serologic backup.