Concordance of two polymerase chain reaction-based blood group genotyping platforms for patients with sickle cell disease.

CONCLUSIONS: In recent years, polymerase chain reaction-based genotyping platforms, which provide a predicted phenotype, have increased in both patient and high-throughput donor testing, especially in situations where serologic methods or reagents are limited. This study looks at the concordance rate between two platforms commercially available in the United States when used for testing samples from patients with sickle cell disease (SCD), a group particularly vulnerable to alloimmunization. DNA extracted from samples from 138 patients with SCD was tested by human erythrocyte antigen (HEA) BeadChip (Immucor, Norcross, GA) and by ID CORE XT (Progenika-Grifols, Barcelona, Spain). Predicted phenotype results were compared, and a concordance rate was calculated. Discrepancies were resolved by Sanger sequencing. All testing was done under an institutional review board-approved protocol. A concordance rate of 99.9 percent was obtained. Sanger sequencing was performed on four samples with discrepancies in the Rh blood group system. Three samples had a similar allelic variant detected by ID CORE XT. Two of the three discrepant samples were correctly identified as V+w, VS- by ID CORE XT but not by HEA BeadChip. The third sample, predicted to have a phenotype of V+, VS+ by sequencing, was called correctly by HEA BeadChip but not by ID CORE XT, which had predicted V+w, VS-. The fourth discrepancy was identified in a sample that ID CORE XT accurately identified as RHCE*ce[712G] and predicted a partial c phenotype. This result was confirmed by Sanger sequencing, whereas HEA BeadChip found no variants and predicted a c+ phenotype. The high concordance rate of the two methods, along with the known limitations of serology, warrant further discussion regarding the practice of serologic confirmation of extended phenotypes. Clinical significance of the identified discrepancies remains to be determined.

Red blood cell phenotype prevalence in blood donors who self-identify as Hispanic.

CONCLUSIONS: Molecular genotyping platforms provide a quick, high-throughput method for identifying red blood cell units for patients on extended phenotype-matching protocols, such as those with sickle cell disease or thalassemia. Most of the antigen prevalence data reported are for non-Hispanic populations. Therefore, this study sought to determine the phenotype prevalence in a single blood center's Hispanic population and to compare those results with previously reported rates in non-Hispanic donor populations. We performed a retrospective review of all serologic and molecular typing from donors who self-reported as Hispanic. The phenotype prevalence was reported and compared with rates from other racial/ethnic groups. A total of 1127 donors who selfidentified as Hispanic were screened by serologic methods for Rh and Kell antigens, and 326 were subsequently selected for molecular typing. The most prevalent probable Rh phenotypes were R1r (26.6%), R1R2 (21.5%), and R1R1 (20.7%); rr was found in 7.8 percent of donors tested. The percentage of K+ donors in this population was 2.8 percent. The most prevalent Duffy phenotypes were Fy(a+b+) (35.9%), Fy(a+b-) (35.6%), and Fy(a-b+) (27%). Of the donors studied, 15.3 percent had an FY GATA mutation. Only 1.5 percent of the donors were Fy(a-b-). The Jk(a+b+) phenotype was found in nearly half of the population. M+N+S+s+ was the most prevalent MNS phenotype from that group, constituting 22.4 percent. A total of 95.7 percent of the donors were Lu(a-b+), and Di(a-b+) was observed in 94.4 percent. The most prevalent Dombrock phenotype was Do(a+b+), constituting 46.9 percent, followed closely by Do(a-b+) at 40.5 percent. Hispanic donor antigen prevalence is distinctly different from other racial/ethnic groups and should be considered when attempting to find extended matched units for these patients.