Rhnull syndrome: identification of a novel mutation in RHce

New RHCE variant alleles encoding the D- - phenotype

BACKGROUND

Variant alleles that do not produce RhCE antigens are rare. Consequently, they pose a challenge to transfusion when found in alloimmunized patients and make blood units valuable when found in donors.

STUDY DESIGN AND METHODS

Five index cases and their relatives were studied by both serologic and molecular techniques. Genomic DNA was subjected to microarray genotyping, sequencing, exon scanning, and/or copy number determination assays to identify the RHCE allele(s) responsible for their D+ C- c- E- e- (D- -) phenotype.

RESULTS

The five apparent D- - phenotypes were confirmed by molecular methods. Three of them contained unreported RHCE-null alleles, namely, RHCE*Ce-D(3-9)-Ce, RHCE*Ce87_93insT, and RHCE*cE221A.

CONCLUSION

Molecular analysis of D- - phenotypes allows the identification of new RHCE-null variants. Conversely, detection of described RHCE-null variants facilitates confirmation of D- - phenotypes in patients and donors, helping improve transfusion safety.

Molecular background of novel silent RHCE alleles

BACKGROUND

The absence of expression of C/c and E/e antigens has been associated with rare variant RHCE alleles, referred to as silent RHCE alleles, classically identified among individuals with a rare D- - or Rhnull phenotype. This work reports on different molecular mechanisms identified in three novel silent RHCE alleles.

STUDY DESIGN AND METHODS

Samples from D- - or Rhnull individuals and their family members, from families for whom Rh phenotype and/or serologic data were unexplained by inheritance of conventional RH alleles, were analyzed. Genomic DNA and transcripts were tested by sequencing analysis.

RESULTS

The first silent allele was a RHCE*cE allele carrying an intronic IVS3+5G>A mutation. The second was a RHCE*ce allele carrying an intronic IVS7-2A>G mutation, whereas the third was a silent RHCE*ce allele carrying a 5-bp deletion (Nucleotides 679-683) in Exon 5.

CONCLUSION

In addition to hybrid alleles and nucleotide deletion, intronic mutations may be associated with the nonexpression of RhCE antigens. Regarding the RH system, silent alleles may not be investigated among D- - or Rhnull individuals only. Rh phenotype and/or serologic data unexplained by inheritance of conventional RH alleles should lead to molecular investigations.