ABSTRACT
BACKGROUND: The Scianna (SC) blood group system comprises seven antigens. They reside on the erythroblast membrane-associated glycoprotein (ERMAP). The ERMAP and RHCE genes are juxtaposed to each other on chromosome 1. We report a novel SC antigen. STUDY DESIGN AND METHODS: Blood samples came from a patient and his two sisters in Saudi Arabia. To investigate the antibody specificity we used the column agglutination technique and soluble recombinant ERMAP protein. The significance of anti-SCAR was evaluated by the transfusion history and a monocyte monolayer assay. We determined the genomic sequence of ERMAP and RHCE genes. RESULTS: The patient's serum showed an antibody of titer 8 against a high-prevalence antigen. The soluble recombinant ERMAP protein inhibited the antibody. The propositus genotyped homozygous for an ERMAP:c.424C>G variant, for which his sisters were heterozygous. The c.424C>G variant occurred in the SC*01 allele in one haplotype with the RHCE*03 (RHCE*cE) allele. No signs of hemolysis occurred following an incompatible blood transfusion. The monocyte monolayer assay was negative. CONCLUSIONS: We characterized a high-prevalence antigen, with the proposed name "SCAR," which is the eighth antigen of the Scianna blood group system (proposed designation 013.008). Individuals homozygous for ERMAP:p.(Gln142Glu) protein variant can produce anti-SCAR. Although we did not observe any sign of hemolysis at this time, the anti-SCAR prompted a change of the treatment regimen. A review of the known reports indicated that all SC alloantibodies of sufficient titer should be considered capable of causing hemolysis.
Subject(s)
Anemia, Sickle Cell/therapy , Blood Group Antigens/genetics , Butyrophilins/genetics , Transfusion Reaction/blood , Alleles , Anemia, Sickle Cell/diagnosis , Anemia, Sickle Cell/genetics , Antisickling Agents/therapeutic use , Blood Group Antigens/immunology , Blood Transfusion/methods , Butyrophilins/immunology , Female , Genotype , Haplotypes , Heterozygote , Homozygote , Humans , Hydroxyurea/therapeutic use , Isoantibodies/genetics , Male , Monocytes/metabolism , Polymorphism, Single Nucleotide , Prevalence , Rh-Hr Blood-Group System/genetics , Rh-Hr Blood-Group System/immunology , Saudi Arabia/epidemiology , Transfusion Reaction/genetics , Young Adult , beta-Thalassemia/complicationsABSTRACT
OBJECTIVE: Second allogeneic hematopoietic cell transplantation (HCT) may be indicated following relapse or graft failure following first HCT. Our retrospective single-center study sought to investigate parameters that influence post-second allogeneic HCT survival. METHOD: We investigated 92 patients who underwent second allogeneic HCT between 1980 and 2016 for relapse or graft failure following first HCT. Median age at second HCT was 41 years (range 16-68), performed for relapse in 59 patients (64%) and for graft failure in 33 patients (36%). RESULTS: On univariate analysis, 3-year OS of the entire cohort was 35% (95% CI=25-45). Eastern Cooperative Oncology Group (ECOG) score (3-year OS 48% for ECOG 0-1, 18% for ECOG 2-3, P=.0006), second HCT indication (3-year OS 43% for relapse, 20% for graft failure, P=.02), time from first HCT to relapse/graft failure (3-year OS for <12months 21%, for ≥12months 46%, P=.009), and conditioning intensity (3-year OS for MA 42% vs other regimens 23%, P=.08) significantly influenced OS. Multivariable analysis confirmed ECOG score (HR=2.15 for ECOG 2-3, 95% CI=1.32-3.51, P=.002) and second HCT indication (HR=1.67 for graft failure, 95% CI=1.02-2.75, P=.04) to independently influence survival. CONCLUSION: Second HCT may offer long-term survival particularly to patients with good performance status who relapse post-first HCT.
