RESUMO
BACKGROUND: The Dombrock (Do) blood group system consists of six distinct antigens: Do(a) , Do(b) , Gy(a) , Hy, Jo(a) , and DOYA. Our finding of a pregnant patient whose red blood cells (RBCs) were Hy+ but whose serum contained an apparent alloanti-Hy suggested the presence of a seventh antigen and prompted this study. STUDY DESIGN AND METHODS: Standard hemagglutination and polymerase chain reaction-based methods were used throughout. RESULTS: The patient's RBCs typed as Do(a-b+(w) ), Gy(a+(w) ), Hy+(w) , Jo(a+(w) ), and DOYA+(w) . Her serum agglutinated RBCs with common Dombrock phenotypes. Hy- RBC samples were very weakly reactive or nonreactive, Jo(a-) and DOYA- RBC samples were reactive, and Gy(a-) RBC samples were nonreactive. Reactivity was obtained with RBCs treated with papain or α-chymotrypsin, but not with RBCs treated with trypsin or dithiothreitol. DNA analysis showed the patient to be DO*793G (DO*B/DO*B), DO*323G, DO*350C, DO*547T, and DO*898G and revealed two homozygous nucleotide changes of DO*431C>A and DO*432C>A in Exon 2, which predicts a change of Ala (GCC) at Amino Acid 144 to Glu (GAA). This indicates that she is homozygous DO*B-WL with Nucleotide 431 and 432 changes, which without knowing the effect of the two novel changes, is predicted to encode the Do(a-b+), Gy(a+), Hy+, Jo(a+), DOYA+ phenotype. CONCLUSIONS: The antibody in the patient's plasma recognizes the high-prevalence antigen absent from her RBCs. The Ala144Glu change caused an absence of a high-prevalence Do antigen that we have named DOMR [provisional ISBT number 014007 (DO7)]. The absence of DOMR is associated with weakening of Do(b) , Gy(a) , Hy, Jo(a) , and DOYA antigens.
Assuntos
Antígenos de Grupos Sanguíneos/imunologia , Antígeno H-Y/imunologia , Antígenos de Grupos Sanguíneos/genética , Eritrócitos/imunologia , Feminino , Hemaglutinação , Humanos , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , GravidezRESUMO
BACKGROUND: The Cromer blood group system consists of seven high-incidence and three low-incidence antigens carried on decay-accelerating factor (DAF). This report describes the identification and characterization of a new Cromer high-incidence antigen, named GUTI. STUDY DESIGN AND METHODS: RT-PCR and sequence analysis were performed on cDNA prepared from a Chilean donor whose serum contained the alloantibody (anti-GUTI). Based on the observed point mutation, a PCR-RFLP assay using MaeII was developed. To map the epitope, DAF-deletion mutants were tested by immunoblotting with anti-GUTI. RESULTS: Sequence analysis revealed a substitution of 719G>A in DAF in the proband. The proband's parents and two daughters were heterozygotes for 719G>A, one sister whose RBCs typed GUTI- was homozygous for 719A, and one sister had the wild-type DAF (719G). Seven additional heterozygote samples were identified among 214 Chileans. No heterozygotes were found in 197 New York donors. Analysis using DAF-deletion mutants showed the antigenic determinant to be within short consensus repeat (SCR) 4. CONCLUSION: This study describes a novel high- incidence antigen (GUTI) in the Cromer blood group system characterized by the amino acid arginine at position 206 in SCR4 of DAF. The GUTI-negative proband has a substitution mutation that predicts for histidine at this position.