Study on seroloy and RHD genotyping of 602 RhD-negative pregnant women and a case of hemolytic jaundice in a neonatal with Del phenotype

[Objective] To characterize the serological profile, RHD genetic spectrum, and their frequencies among pregnant women preliminary screened as RhD-negative and weak positive in Qingdao and surrounding areas, and correlate these findings with unexpected antibody detection results, thereby providing testing recommendations and suggestions for such individuals. [Methods] Blood samples of pregnant women who were initially identified as RhD negative and weak positive in hospitals in Qingdao and surrounding areas over the past five years were collected. Different cloned IgG anti-D antibodies were used for RhD negative confirmation experiments. RHD genotyping was performed by combining PCR-SSP and Sanger sequencing. Unexpected antibody screening and identification were carried out using test tube method and microcolumn gel card. The immunologic status of newborns delivered by anti-D pregnant women was also tracked. [Results] A total of 602 blood samples were collected from pregnant women initially identified as RhD-negative and weak positive. Among them, 569 (94.5%) were confirmed as RhD-negative in the RhD confirmation test, and 33 (5.5%) were D variant phenotype. Except for 4 cases where no definite mutations were found, gene analysis revealed 474 (78.7%) D-negative cases with 5 genotypes (RHD*01N.01, RHD*01N.03, RHD*01N.16, RHD*01N.05, and 1 new allele), 90 (15.0%) Del cases with 2 genotypes (RHD*01EL.01, and RHD*01EL.18), 23 (3.8%) weak D cases with 2 genotypes (RHD*15 and 1 new allele), and 11 (1.8%) partial D cases with 2 genotypes (RHD*06.03.01 and RHD*05.04). Anti-D and complex antibodies containing anti-D were detected in 96 RhD-negative and partial D pregnant women (15.9%). After injection of anti-D immunoglobulin, One O-type RhD-negative pregnant woman delivered a newborn with hyperbilirubinemia. The newborn was typed to be B Del, and anti-D was detected in both serum and eluate. [Conclusion] The serological profiles, RHD gene types and frequencies among RhD negative pregnant women in Qingdao and surrounding areas are basically consistent with domestic published data. Pregnancy can stimulate anti-D production in D-negative and partial D individuals. However, anti-D antibody has not been detected in Del type pregnant women. Since anti-D immunoglobulin can binds to Del type red blood cells, its administration is not recommended for Del type pregnant women.