Title of presented paper: Rhnull -- a golden blood.

Introduction and aim. The Rh blood group system consists of at least 61 independent antigens. It was first described in 1939 and has since played a key role in blood group differentiation. The classical division distinguishes Rh+ and Rh- groups, however, an atypical phenotype known as Rhnull is also present, which is associated with the formation of all-antibodies on contact with Rh antigens, which can pose a significant problem in patients who have it and require blood transfusions. Material and methods. Four case reports and one review paper were used. The articles are from 1992-2020. PubMed and Google Scholar databases were used. Key words used in the search were blood transfusion, golden blood and Rhnull. Analysis of literature. The Rhnull blood phenotype (also called "golden blood") is a rare blood type with a prevalence of about 1 in 6 million people. To date, at least 43 individuals belonging to 14 families with the Rhnull phenotype are known, with reports in the literature up to 2018. A mutation in the RHCE gene is most often responsible for its formation. The characteristic feature of "golden blood" is the absence of all Rh antigens on red blood cells. Previous reports indicate its role in the development of hemolytic anemia secondary to a defect in the erythrocyte cell membrane. Conclusion. The presence of rare blood phenotypes can pose a significant problem in the process of blood transfusion in patients. Blood marriages, common in eastern countries and Africa, play an important role in the formation of the Rhnull phenotype, which is more common there compared to other regions of the world. Further genetic studies are needed to find the mutations underlying the development of Rh group incompatibility. [ABSTRACT FROM AUTHOR]