A study recently published in Transfusion identified a new genetic mutation in the RHCE gene that may lead to hemolytic disease of the fetus and newborn (HDFN).
Typically, individuals express the RHCE gene and produce some combination of C, c, E and e antigens on their red blood cells. However, the D– blood group is a very rare phenotype in which individuals do not express any of the antigens encoded by the RHCE gene. Usually, these patients have heightened expression of the D antigen, encoded by the RHD gene.
The Rh17 antigen is found in almost all individuals and is also encoded by the RHCE gene. Those with the D– blood type, therefore, may lack this antigen and will produce antibodies against it when exposed following an incompatible blood transfusion or during pregnancy. This, in turn, can lead to HDFN.
The authors identified a 55-year old male who was found to have the D– blood group after routine RhD and RhCE testing at Jiangxi Provincial People’s Hospital, China. Additionally, the same phenotype was discovered in an 8-month-old baby producing anti-Rh17 antibodies.
Read more about HDFN causes and risk factors
In both patients, an identical mutation was discovered within the promoter region of the RHCE gene. The promoter is the portion of DNA that serves as a site for initiation of gene expression. In particular, the mutation was within the GATA-1 motif, a short DNA sequence that binds a protein that helps to regulate gene expression.
Furthermore, the study confirmed that this single-nucleotide mutation in the RHCE promoter downregulated gene transcription by 72%.
“The routine screening and storage of D– blood is very crucial for the guarantee of blood supply in D– patients and the newborns suffering from severe HDFN due to anti-Rh17,” the authors concluded.
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