A Japanese propositus with D-- phenotype characterized by the deletion of both the RHCE gene and D1S80 locus situated in chromosome 1p and the existence of a new CE-D-CE hybrid gene.
In a family study of a Japanese propositus with the D-- phenotype, the serological data of her D-- phenotype and those of her parents were discrepant. Gene analysis of the propositus showed a gross deletion of the RHCE gene and a new rearrangement of RHCE to yield the CE-D-CE hybrid. It was demonstrated that the hybrid CE-D-CE gene consisted of exon 1 from the RHCE gene, followed by exons 3 to 7 from the RHD gene and exons 8 to 10 from the RHCE gene. However, whether or not exon 2 of the RHD or the RHCE gene was contained in the CE-D-CE gene remained unclear. Moreover, spacer analysis between both RH genes and the family study suggested that the D-- gene complex from the paternal and maternal sides consisted of only the CE-D-CE hybrid gene and a single RHD gene, respectively. For the purpose of confirming the parent-child relationship, a paternity test using DNA fingerprint and polymerase chain reaction (PCR) analysis at the D1S80 locus were performed. DNA fingerprints with two kinds of DNA minisatellite probes (33.15 and 33.6) confirmed that the parent-child relationship in the D-- propositus was compatible. However, in the present case, at the D1S80 locus, the PCR product derived from the mother was lacking, thereby negating a parent-child relationship. It is probable that the RH genes and D1S80 locus exist in close proximity, because they are situated in chromosomes 1p 34.3-36.1 and 1p 36.1-36.3, respectively. These data suggested that at the stage of gametogenesis, both the RHCE gene and the D1S80 locus from the maternal side may have been deleted, thereby producing the D-- gene complex.