Molecular characterization of a rare Rh phenotype Dc-from the Indian subcontinent

Unusual Rh phenotypes such as Rh_null, D-- and Dc- etc. are rarely encountered in routine blood bank testing. The Rh_null phenotype is characterized by the absence of all Rh antigens, D-- phenotype does not express any RhCcEe antigens whereas Dc- phenotype individual lacks expression of antithetical E /e antigens. These individuals may produce multiple Rh antibodies against missing antigens. An old woman (B RhD positive) from Bangladesh with end-stage renal disease developed severe anaemia. Cross-matching with ABO and RhD compatible blood units showed +3 agglutination reaction. Detailed immunohaematological investigations showed a lack of C, E and e antigens, thus identifying the rare Rh variant as Dc-. Antibodies against C and e antigens were also detected in the patient's serum. PCR-SSP confirmed the absence of the molecular region defining the C, E and e antigens. Copy number analysis by QMPSF revealed the homozygous state of (RHCE-D(4-9)-CE) allele at the RHCE gene locus. This is the first report of the rare Dc- variant individual from the Indian subcontinent.