Tehran University of Medical Sciences International Journal of Hematology-Oncology and Stem Cell Research 2008-2207 15 4 2021 10 14 213 220 EN Younes Sadeghi-Bojd Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran Naser Amirizadeh Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran Arezoo Oodi Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran 2020 05 10 2020 08 31 Background: The D antigen is a subset of Rh blood group antigens involved in the hemolytic disease of the newborn [HDFN] and hemolytic transfusion reaction [HTR]. The hybrid Rhesus box that was created after RH gene deletion, was known as a mechanism of the Rh-negative phenotype. Hybrid marker identification is used to confirm the deletion of the RHD gene and to determine zygosity. This study aims to detect this marker in Rh-negative and weak D phenotype blood donors of the southeast of Iran. Materials and Methods: The molecular analysis of the hybrid Rhesus box was performed on the 200 Rh-negative blood donors in Sistan and Baluchestan province, southeast Iran. The presence of alleles responsible for the D variants was assessed by DNA sequencing in 26 weak D phenotype donors. Results: Of the 200 Rh-negative blood samples, 198 samples were homozygous (99%), and two samples were heterozygous (1%). Heterozygous samples had RHD*01N.73 allele and the RHD*01N.18 allele. Of the 26 samples with weak D phenotype, 16 partial DLO (61%), 4 partial DBT1 (15.3%), 2 partial DV type 2 (7.7%), 1 weak D type 1, 1 weak D type 4.2.3, 1weak D type 105 and 1 RHD (S103P) (4%) were determined. Conclusion: Since RHD gene deletion is the main mechanism of the Rh-negativity in Sistan and Baluchestan provinces, a hybrid Rhesus box marker can be used in resolving RhD typing discrepancies by RHD genotyping methods. https://ijhoscr.tums.ac.ir/index.php/ijhoscr/article/view/1335 https://ijhoscr.tums.ac.ir/index.php/ijhoscr/article/download/1335/887