University of California San Francisco San Francisco, California, United States
Background/Case Studies: Rh(D) typing discrepancies are encountered with current and historical results, forward or reverse typing, and results by different methodologies or platforms do not match. While evaluating an Rh(D) discrepancy, the distinction between weak D and partial D is crucial since the individuals with partial D may make alloanti-D antibody that can cause hemolytic disease of the fetus or newborn (HDFN), which is a preventable disease in patients with partial D. Here we describe a single-center experience with Rh(D) discrepancies.
Study
Design/Methods: We evaluated patients with Rh(D) discrepancies between 2015 and 2025 and reported on serological and genotype results. Serological testing was performed via automated gel technology (AGT) and tube testing, and the reactivity of the serological reaction, graded from 0 to 4+, was compared via t-test for confirmed partial D vs weak D and the two testing platforms.
Results/Findings: A total of 47 patients had Rh(D) discrepancies during the study period (22 men and 25 women, M: F ratio of 0.88). There were 100 serological tests performed for these patients: on average, 2.12 ± 0.84/patient. RHD genotype was performed in 17 males (77%) and 18 females (72%). Eleven females (23% of total patients) were in the reproductive age group (< 50 years old), and 8 (72%) had RHD genotype performed. The majority (66%, 23/35 patients) demonstrated Weak D (13 type 1, five type 2, two type 3, two type 4.0 and one type 4.1; a minority (23%, 8/35) were partial D cases (one of each DIVa, DAUS, DAU4, DVII, DV Type 4, XIV, DIIIa and C674C >T single nucleotide variant); and four (11%) did not have variants. A detailed classification of reactivity strength is illustrated in Table 1. Genetically confirmed partial D had a stronger serological reactivity than weak D in AGT (4+ vs 2+) and tube testing (1+ vs w+), and the difference was statistically significant in both platforms (p=1.78E-05 and p=0.12 for AGT and tube testing, respectively).
Conclusions: This study highlights the importance of genotype confirmation in patients within the reproductive age group for HDFN prophylaxis, as a strong serological reactivity may be misinterpreted as Rh(D)-positive.
