Rh Null Blood Group Caused by New Base Deletion and Pedigree Analysis

Objective: To study and discuss the formation mechanism of Rh null blood group in a case from the perspective of genetics, and to study the Rh blood group genes of its family members. Methods: Rh blood group phenotype of the proband was detected by serology. RHCE genotyping, RHD, RHCE sequencing and RHAG exons sequencing were performed, and then the mechanism of Rh null formation in the proband was analyzed. For comparison, the same methods were used to detect two family members of the proband. Results: The genotype of the proband was CcDEe, and the RHAG exon sequencing showed a homozygous frameshift mutation, with the mutation site at Exon 5, nucleotide changed as c.732delC, and amino acid change as p.Phe245Serfs*16. The serological results, genotyping, RHAG exon sequencing and mutation location of the sister of the proband were the same as those of the proband; The serological result of her son was CCDee, the genotyping result was CCDee, and the RHAG exon sequencing result was heterozygous frameshift mutation, consistent with the proband. Conclusion: A new mutation site c of RHAG gene was detected 732delC. The formation mechanism of Rh null in the proband is RHAG gene frameshift mutation and homozygous, which leads to the incomplete expression of RhAG protein in the patient and affects the expression of other Rh antigens on the cell membrane. The serological result is Rh null.