Rhnull phenotype in an Indian patient due to a novel c.1138 + 2 t > a mutation in the RHAG gene

Abstract

Background: The Rh system is an extremely important RBC antigen system with over 50 antigens, 5 of which (D, C, E, c and e) are considered most clinically significant. The rare Rhnull phenotype can result from mutations in the RHD and RHCE genes or the RHAG gene that affects their expression. This is a case report of the second type.

Case report: This case reports a multiparous lady who had to be evaluated for a panreactive antibody. The discrepancy was first identified at the centre she reported to. A thorough immunohematological workup was performed at a second reference laboratory. Suspecting Rhnull phenotype, a third referral (molecular typing) was requested at International Blood Group Reference Laboratory (IBGRL), Bristol.

Results: A novel RHAG null allele (c.1138+2t>a), causing a Rhnull phenotype was identified. The antibody was most likely an anti-Rh 29 antibody.

Conclusion: The novel c.1138+2 t > a mutation in the RHAG gene causing the Rhnull phenotype and development of a pan reacting antibody(ies) made the patient's pregnancy challenging. Confirmation of the diagnosis, an important step in her management, required use of both serological immunohematology and molecular techniques.

Keywords: RHAG; Rhnull; novel allele.