Anti-G antibody mimics the reactivity pattern of coexistent anti-D and anti-C. Differentiating between the two is significant in antenatal females where the decision to administer RhD prophylaxis is based on the presence or absence of anti-D antibody. The aim of reporting this serological challenge is to emphasize the need for phenotyping red cells for sourcing appropriate in house red cell reagents and to help transfusion services sharpen problem-solving skills. A 26-year-old pregnant female with a complicated obstetric history and a positive indirect antiglobulin test presented to the hospital for antenatal assessment at 24 weeks. A positive antibody screen warranted identification of the implicating antibodies. Since identification was suggestive of multiple alloantibodies whose specificities could not be confirmed, step-wise sequential adsorption and elution was required. Anti-D, anti-C, and anti-E antibodies were identified in patient plasma with titers of 1024, 4, and 32, respectively. The absence of anti-G was also confirmed. Multiple alloantibodies can pose a challenge to transfusion services. However, with the help of select cells, phenotyping, adsorption elution studies, and phenotyped donor units; solving complex serological cases can be accomplished.

Anti-G is commonly present with anti-D and anti-C and can confuse serological investigations. The differentiation of anti-G from anti-D and anti-C is particularly essential for the accurate diagnosis of hemolytic disease of the fetus and newborn (HDFN) and appropriate administration of anti-D immunoglobulin prophylaxis in Rhesus (Rh) negative women. We reported a rare case of anti-G together with anti-D and anti-C in a pregnant woman and her female neonate. The titers of IgG anti-D, anti-C, and anti-G in the woman were 256, 128, and 32, respectively. While the titers of IgG anti-D, anti-C, and anti-G in the neonate were 16, 8, and 4, respectively. The neonate experienced mild HDFN and only received phototherapy during hospitalization. This report discusses the diagnostic strategy and clinical significance of differentiating anti-G from anti-D and anti-C.

BACKGROUND: Anti-G antibodies are rarely found since anti-D, in combination with anti-C, are difficult to discriminate from anti-G antibodies in routine testing.
METHODS: A 22-year-old, gravida-3, para-1, woman with blood group A Rh D neg ccddee and known antibody anti-Jk(b), gave birth to her second child. While anti-Jk(b) could not be detected at birth, a new anti-C was found. Antibody screening tests (IAT) were performed using gel cards and rare G positive rGr erythrocytes. Genotyping for RHD and RHCE was performed using PCR-SSP.
RESULTS: The child\'s blood group was A Rh D neg Ccddee. Genotyping revealed Cde/cde haplotypes. The erythrocytes of the new-born showed a positive direct antiglobulin test with IgG; anti-D and anti-C could be eluted. Erythrocytes with the rare phenotype rGr were reactive with the serum of the mother.
CONCLUSIONS: The presence of anti-D and anti-C in the eluate from then newborn\'s Ccddee erythrocytes proved anti-G or anti-G in combination with anti-D. When anti-C and anti-D are seen during a pregnancy, possibly anti-G is present. This observation is of relevance since women with anti-G can still develop anti-D and require rhesus prophylaxis.