Published in:
01-04-2019 | Correspondence
A Case Report of a Rare Rh Phenotype: D—
Authors:
Maryam Samareh Salavati Pour, Saeed Soleimany, Narges Ghasemimehr, Roohollah Mirzaee Khalilabadi
Published in:
Indian Journal of Hematology and Blood Transfusion
|
Issue 2/2019
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Excerpt
Rh blood group (ISBT: 004) is the second major blood grouping system in addition to ABO, which was first described 60 years ago [
1,
2]. Rh factor is an inherited blood protein or antigen on red blood cells [
2]. This system includes at least 45 independent antigens from which D, C, c, E, and e are more important for transfusion medicine [
3]. Among Rh antigens, e is the most common antigen (98.3%), followed by D (94.2%), C (88.11%), c (54.5%), and E (18.6%) [
4]. Rh blood group antigens are highly complicated because of polymorphism in genes encoding them [
5]. D and CE proteins/antigens in the Rh blood group system are encoded by RHD and RHCE genes stretching along a 75 kb sequence located on chromosome 1p36.11. Each Rh gene consists of 10 exons that are highly homologous with 93.8% amino acid identity, and RHAG protein on RBC surface is necessary for the expression of Rh antigens. Because of high immunogenicity, D antigen has been recognized as the most important Rh antigen that is used for Rh blood grouping [
3]. One of the rare Rh phenotypes is D—, which was first described in 1950 by Race and Sanger. In this phenotype, RHCE proteins are not expressed on RBC membrane. After immune stimulus, individuals with D— phenotype produce an alloantibody known as AntiRh17 (AntiHr0) against CcEe antigens that can lead to the development of a hemolytic transfusion reaction (HTR) or hemolytic disease of newborn (HDN) [
6‐
8]. Several genetic bases have been known to be responsible for this phenotype: (1) reduced transcription of CE gene, (2) RHCE deletion, (3) gene hybridization between RHD and RHCE genes because of their highly homologous nature. In the description of the last theory, studies showed that a hybrid gene only produced the D antigen [
9,
10]. Immunoblotting techniques showed that the expression of D antigen and ICAM4 (LW) was increased whereas CD44 antigen and related blood group antigens were reduced [
6]. Herewith, we have reported a case of a woman with rare D— phenotype. …
