ceRA: an RH allele variant producing a new rare blood.
BACKGROUND
Antibodies against RH antigens are clinically significant. Some rare RH phenotypes, for example, RH:-46 (R(N)), RH:-18 (Hr(s)-), RH:-34 (Hr(b)-), and homozygous partial RH5 (e), are found exclusively in black persons of African descent. Quantitative and qualitative RHCE variants require characterization because the presence of these alleles can lead to difficulties when transfusion is needed.


METHODS
Here a new RH5 variant (ceRA) in an Indian patient is described and investigated by serology (agglutination and flow cytometry analysis) and molecular and immunoblot analysis.


RESULTS
Red blood cells (RBCs), typed as RH:-1,-2, -3,4,w5, expressed a very depressed RH5 antigen, with no expression of the RH19 (h) high-frequency antigen. Molecular analysis revealed a new Rhce allele (homozygous state), hereafter called ceRA. This new allele exhibited a G48C mutation in exon 1 and a G538C mutation in exon 4, predicting, respectively, a Trp16Cys substitution and a Gly180Arg substitution, both in the intramembranous domain of the Rhce polypeptide. Immunoblot analysis showed that this defect results in a dramatic loss of the amount of RHCE polypeptides within the RBC membrane. No reactivity was evidenced with most of anti-RH5, in agglutination as well as in flow cytometry techniques.


CONCLUSIONS
Both serologic results and localization of the Gly180Arg substitution emphasize the risk of anti-RH5 alloimmunization for patients expressing this new allele ceRA at the homozygous state. These results point out the importance of obtaining blood donations for the frozen rare blood bank in case future transfusion is needed.
Noizat-Pirenne
France
F
Etablissement Français du Sang Ile de France, Henri Mondor Hospital, Créteil, France.
Tournamille
Christophe
C
Gallon
Philippe
P
Juszczak
Geneviève
G
Rouger
Philippe
P
Ansart-Pirenne
Hélène
H
D000483:Alleles; D001787:Blood Group Incompatibility; D001788:Blood Grouping and Crossmatching; D005091:Exons; D014644:Genetic Variation; D006720:Homozygote; D006801:Humans; D007194:India; D020125:Mutation, Missense; D017354:Point Mutation; D012204:Rh-Hr Blood-Group System / Q000235:genetics*; D044465:White People
D012204:Rh-Hr Blood-Group System