AbstractBackground and AimThe Duffy (FY) blood group system has six known antigens among which the Fyaand Fybare known as major antigens. Fyxphenotype forms as a result of two point mutations in theFYBallele leading to instability of Duffy protein and so reduction of Duffy antigen expression in the cells. This study aimed to investigate theFYXallele frequency in the Scottish population.MethodsThe Duffy blood group system was serologically and molecularly investigated in 222 samples collected from donors of Aberdeen Regional Blood Transfusion Center (BTC). The haemagglutination and BeadChip microarray chemistry methods were used for phenotyping and genotyping. Confirmatory tests were also used to check the discrepant results.ResultsIn this study, the frequency of Duffy blood group phenotypes including Fya+, Fya+b+, and Fyb+were 17.57%, 42.79%, and 39.64%, respectively. Furthermore, the frequency ofFYA/FYA,FYA/FYB, andFYB/FYBgenotypes was estimated to be 14.41%, 45.95%, and 39.64%, respectively, using the Bioarray method. In the present study, based on Duffy DNA sequencing results, 12 samples (5.41%) had just oneFYXallele.ConclusionThe frequency of theFYXallele in this study was estimated to be 0.0270% which is more than the results reported so far.