D Variants In The Population Of D-Negative Blood Donors In The North-Eastern Region Of Croatia

Objectives The aim of this study was to determine RHESUS D GENE (RHD)allelic variants among Croatian D-negative blood donors and compare our results with respective data from other European countries. Background Altered or reduced D antigen expression can result in D variants, which can be mistyped and can lead to the alloimmunisation of the blood recipient.RHDgenotyping can distinguish D variants: weak D, partial D and DEL, thus preventing alloimmunisation. Material/methods A total of 6523 samples obtained from D-negative Croatian donors were screened for the presence ofRHDusing the real-time polymerase chain reaction (PCR) method. PCR-SSP was performed for D variant genotyping by using commercial genotyping kits (Inno-Train, Kronberg, Germany). Genomic DNA sequencing for all 10 exons of theRHDwas performed when the genotyping kits failed to assign a D variant. Results RHDmolecular screening revealed 23 (0.35%)RHD-PCR positive samples, all C/E positive, in decreasing frequency: 11 hybridRHD-CE (2-9) D-CEvariants, 4 weak partial D type 11 and 2 weak D type 2. Six samples remained unresolved and were sequenced. For 12 of 23 samples (excluding large hybrids), an adsorption/elution of anti-D serum was performed, confirming that all 12 were RhD+. The calculated frequency of clinically significant D alleles in RhD-negative blood donors was 1:543 (0.18%) or 1:53 (1.89%) in C/E blood donors. Conclusion Data on the significant frequency of D variants among serologically D-negative blood donors in the north-eastern region of Croatia could help in introducingRHDmolecular screening of blood donors in a routine workflow.