RH locus contraction in a novel Dc-/D-- genotype resulting from separate genetic recombination events.
BACKGROUND
The rare phenotypes Dc- and D-- lack the expression of E/e and CcEe antigens, respectively; their cotransmission in a single family has not been reported.


METHODS
Six members of a Chinese family with two exhibiting the Dc- phenotype were studied using standard serologic methods. Rh genotypes were analyzed by Southern blot, and RH loci, by exon PCR. Rh transcripts were characterized by gene-specific RT-PCR and sequencing.


RESULTS
Although Rh typing detected two members as Dc- homozygotes, RFLP analysis and exon PCR showed them to be Dc- heterozygotes with a partial deletion of RHCE. cDNA sequencing showed the expression in the family of normal RHD and RHCe as well as hybrid transcripts, RHD(1-9)/RHCE(10) and RHCE(1-3)/RHD(4-10). Thus, the Dc- members had the genotype of Dc-/ D-- and expressed both hybrid genes that were inherited from their parents, respectively.


CONCLUSIONS
This is the first demonstration in a family that the Dc- and D-- complexes neither are linked with a normal RHD or RHCE gene. The segregation of these two different hybrid genes with single break points suggests their independent genetic origin and provides molecular insights into the dynamic nature of genomic rearrangements leading to RH locus contraction.
Huang
C-H
CH
Biochemistry and Molecular Genetics Laboratory and the Immunohematology Laboratory, New York Blood Center, New York, New York 10021, USA. chuang@nybloodcenter.org
Peng
J
J
Chen
H C
HC
Chen
Y X
YX
Lin
D-T
DT
Lin
S W-S
SW
Reid
M E
ME
Powell
V I
VI
D000328:Adult; D044466:Asian People / Q000235:genetics; D015139:Blotting, Southern; D002648:Child; D002681:China; D018076:DNA, Complementary / Q000235:genetics; D005091:Exons / Q000235:genetics; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D010375:Pedigree; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012333:RNA, Messenger / Q000235:genetics; D011995:Recombination, Genetic; D012204:Rh-Hr Blood-Group System / Q000737:chemistry / Q000235:genetics*; D017384:Sequence Deletion; D014158:Transcription, Genetic
D018076:DNA, Complementary; D012333:RNA, Messenger; D012204:Rh-Hr Blood-Group System; C026410:Rho(D) antigen