Molecular analysis of the structure and expression of the RH locus in
individuals with D--, Dc-, and DCw- gene complexes
B Cherif-Zahar, V Raynal, AM D'Ambrosio, JP Cartron and Y Colin
Unite INSERM U76, Institut National de Transfusion Sanguine, Paris, France.
Rh blood group antigens of the D, C/c, and E/e series are carried by at
least three red cell membrane polypeptides encoded by two highly related
genes, RHD and RHCE. Homozygous individuals carrying the D--, Dc-, and DCw-
gene complexes are characterized by a total or partial lack of expression
of the RHCE-encoded antigens. Analysis of the molecular genetic basis of
these rare conditions indicates that complete or partial expression defect
of Cc/Ee antigens result from different alterations at the RH locus, but
not from gross deletions. No rearrangement or mutation of the RHCE gene
could be detected in donors homozygous for the D-- complex, suggesting that
the lack of the Cc and Ee antigens might result from a reduced
transcriptional activity of the RHCE gene. The Dc- and DCw- gene complexes,
however, exhibited an important rearrangement of the RHCE gene. Instead of
the normal RHCE gene, both variants carried a hybrid RHCE-D-CE gene in
which exons 4 to 9 (Dc- complex) and 2 (or 3) to 9 (DCw- complex) of the
RHCE gene, respectively, have been substituted by the equivalent region of
the RHD gene. These gene conversion events provide an explanation for the
well- described abnormal antigen profiles associated with the Dc- and DCw-
complexes, like the increased expression of RhD, the reduced expression of
RhC/c or RhCw, and the absence of RhE/e.
Volume 84,
Issue 12,
pp. 4354-4360,
12/15/1994
Copyright © 1994 by The American Society of Hematology
