Transcript Document
June 6, 2013
What Keeps us up at Night
The New Frontier in Blood Banking HEA Molecular Testing
Sylvia M. Garza MT-P(AAB)
Objectives:
1. Define terms.
2. Discuss HEA molecular testing process.
3. Present case study demonstrating serological results that surprisingly differs from molecular results.
4. Review conclusions.
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Terminology Definitions 101
• Genotype- An individual’s actual genetic makeup.
2(p621) Genotype of a person is the complement of genes inherited by each person from his or her parents; the term is frequently also used to refer to the set of alleles at a single gene locus.
1(p334) • Phenotype- The outward expression of genes (e.g., a blood type). On blood cells, serologically demonstrable antigens constitute the phenotype, except those sugar sites that are determined by transferases.
2(p629) • Polymorphism for blood groups- the occurrence in the same population, of two or more alleles at one locus, each with appreciable (greater than 1%) frequency.
1(p335) • Allele- One or two or more different genes that may occupy a specific locus on a chromosome.
2(613)
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Terminology Definitions 101 cont.
• Locus- The site of a gene on a chromosome.
2(p625) • Chromosome- The structures within a nucleus that contain a linear thread of DNA, which transmits genetic information. Genes are arranged along the strand of DNA and constitute portions of the DNA.
2(p616) • DNA (Deoxyribonucleic Acid)- The chemical basis of heredity and carrier of genetic information for all organisms, except RNA viruses. Structured as a double helix of polymers of nucleotides, each containing bases (A, T, C, and G), sugar deoxyribose, and three phosphates. They become monophosphates once they are built into DNA molecules.
2(p618)
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BioArray Platform
• The HEA BeadChip TM (Bioarray Solutions, Immucor) analyzes 24 polymorphisms associated with 38 Human Erythrocyte Antigens and phenotypic variants are included in the BioArray Solutions HEA BeadChip TM kit.
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Principles of the Assay
• The BioArray Solutions HEA BeadChip TM Kit uses the proprietary Elongation mediated Multiplexed Analysis of Polymorphisms (eMAP®) technology to identify the presence or absence of the selected alleles associated with a phenotype. After multiplex PCR amplification and post-PCR, the single-stranded DNAs are incubated on the BeadChip TM array. Elongation reaction extends and incorporates fluorescently-labeled dNTP molecules only on those probes where the 3’ end matches the annealed DNA. Elongation products of alleles A and B are simultaneously detected by imaging the entire array.
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•
Principles of the Assay cont.
In this method, each probe is covalently attached to a distinguishable bead type. A library of individual bead types contain all of the probes of interest. The library is immobilized in the BeadChip TM array, allowing for the detection of the polymorphisms of interest.
Table 1: Genetic Markers for Red Blood Cell Antigens in the BeadChip Assay
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Blood Group System Analyte Nucleotide Polymorphism ISBT Phenotype ISBT Genotype
c/C 307 C>T 109 Ins RH4, RH2
RHCE*4, RHCE*2
Rh Kell Duffy Kidd e/E Vs V K/k Js a /Js b Kp a /Kp b Fy a /Fy b GATA (Silencing
FY)
Fy x [Fy(b+ w )] Jk a /Jk b 676 G>C 733 C>G, 1006 G>T 698 T>C 1910 C>T 961 T>C 125 G>A -67 T>C* 265 C>T 838 G>A RH5, RH3 RH20 RH10 KEL1, KEL2 KEL6, KEL7 KEL3, KEL4 FY1, FY2 FY-2 FY2W JK1, JK2
RHCE*5, RHCE*3 RHCE*01.20.01, RHCE01.20.02, RHCE*01.20.04, RHCE*01.20.05 KEL*01, KEL*02 KEL*06, KEL*07 KEL*03, KEL*04 FY*01, FY*02 FY*02N.01
MNS M/N S/s Silencing S Silencing S 59 C>T 143 T>C Ex5 230C>T In5 g>t MNS1, MNS2 MNS3, MNS4 MNS-3, 5W Lutheran Dombrock Lu a /Lu b Do a /Do b Hy+/Hy- Jo(a+)/Jo(a-) 230 A>G 793 A>G 323 G>T 350 C>T LU1, LU2 DO1, DO2 DO4 DO5 Landsteiner Wiener Diego Colton LW a /LW b Di b /Di a Co a /Co b 308 A>G 2561 C>T 134 C>T LW5, LW7 DI2, DI1 CO1, CO2 Scianna Sc1/Sc2 169 G>A SC1, SC2 * The GATA mutation listed here has been previously reported at -33 and -46[
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].
FY*02M JK*01, JK*02 GYPA*01, GYPA*02 GYPB*03, GYPB*04 GYPB*03N.01 or GYPB*03N.02
GYPB*03N.03 or GYPB*03N.04 LU*01, LU*02 DO*01, DO*02 DO*04 DO*05 LW*05, LW*07 DI*02, DI*01 CO*01, CO*02 SC*01, SC*02
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P/N 190-00210 Rev G page 5 Issue Date: 08-2012
Principles of the Assay cont.
• The BioArray Solution Array System (AIS400) is used to capture the fluorescent signal from individual beads in an image of the entire array, determine the identity of the bead by color and report the average signal intensity, coefficient of variance of the intensities, and the number of beads measured for each type of probe.
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Principles of the Assay cont.
• The HEA Analysis software in BioArray Solutions Information System (BASIS generates assay results.
TM ) imports the raw intensity output, assesses the validity of the internal controls, and
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Process
DNA Extraction • Whole blood Multiplex PCR • Amplification with Phosphorylated Primers Post PCR Processing • Cleanup and Digestion Post PCR Processing • Annealing and Elongation Assay Image Acquisition and BeadChip TM Analysis
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Serology vs. Molecular Case Study
1. Patient Background We followed an African American Woman (type A Neg) with Sickle Cell Anemia from 2006-2013 and reviewed her history. Between 2006-2013, 41 PRBC’s were transfused with no reported transfusion reactions. 2.
Initial Serological Results To obtain the patient’s phenotype, we elected to perform the hypotonic saline wash technique due to the patient’s recent transfusions. Patient’s Serological phenotype:
C+ E c+e+; M N+ S s+; K- Fy(a-b-) ; Jk (a+ b )
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Serology vs. Molecular Case Study
• 2.
Initial Serological Results cont.
Summation of Results 2006-2009: -Anti-Fy a , Anti-Js a and Warm Autoantibody (autoanti-e) • 2012 The transfusing facility reports that another facility identified: Anti-E, Anti-K and Anti-C. So now the patient has Anti- Fy a , -Js a , -E, -K and Anti-C.
Anti-C, when the patient’s serotypes as C+ ????
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Report Date/Time: Lot #: Chip Read Date/Time: Human Erythrocyte Antigen (HEA) Phenotyping by DNA Analysis Report
May 15, 2013 06:49 AM 12-2 May 2, 2012 10:48 PM
Sample I D: Chip I D:
Joseph, Judith HEA82837_1 Florida Blood Services 10100 Martin Luther King Jr. St.
North St. Petersburg, FL 33716
Blood Group
Rh Kell Kidd Duffy MNS Lutheran Diego Colton Dombrock Landsteiner-Wiener Scianna
Antigen
c C e E K k Kpa Kpb Jsa Jsb Jka s Lua Lub Dia Dib Coa Jkb Fya Fyb M N S Cob Doa Dob Joa Hy LWa LWb Sc1 Sc2 HbS
Result
+ (0)* 0 + 0 + 0 0 + 0 + 0 + + 0 0 0 0 + + 0 + + 0 + 0 ++ + 0 0 + + +
Detail: Notes:
Hemoglobin S Possible VS+V-
Status Code
CV - Coefficient of Variation of intensities exceeds recommended maximum LS - Low Signal: signal intensity below recommended minimum HB - High Background: exceeds recommended maximum IC - Indeterminate call Signature: Name (Print):
Detail Code
Fyb(w) - Weak Fyb expression due to mutated FY265 Hy - or Jo(a) - Published reports indicate observation of a "negative" phenotype; some RBC may react weakly U(-) - Possible U(-) due to GYPB gene deletion U(var) - Variant U detected involving S silencing mutation Date: Title: Blood Group Phenotype DNA Analysis By: Elongation - mediated Multiplex Analysis of Polymorphisms
Notes General Disclaimer
(0)* - Possible r' S w - Weakly Expressed phenotype
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Serology vs. Molecular Case Study
The (0) * may indicate a possible r ’ S So what is r ’ S ? Why do we care? So what is r ’ S ? Patient’s who are R 2 r ’ S or homozygous r ’ S will be hr B and can produce anti-hr B .
3(p65) In our case, this is why we care.
r ’ S phenotype also expresses partial C and these patients are at risk to form anti-C.
3(p65) Could this explain our anti-C?
We need to look at the patient’s Genotype to see if the patient is homozygous for r ’ S .
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Report Date/Time: Lot #: Chip Read Date/Time: Status: Notes:
Ax(1)
Human Erythrocyte Antigen (HEA) Genotyping by DNA Analysis Report
May 15, 2013 06:50 AM 12-2 May 2, 2012 10:48 PM
Sample I D:
Joseph, Judith
Chip I D:
HEA82837_1 Florida Blood Services 10100 Martin Luther King Jr. St.
North St. Petersburg, FL 33716
Detail: Polymorphism
RhCE-P103S RhCE-109Ins RhCE-A226P RhCE-L245V RhCE-G336C K1/K2 Kp Js JKA/JKB FYA/FYB GPA GPBS LUA/LUB DIA/DIB COA/COB DO-793 DO-350 DO-323 LWA/LWB SC1/SC2 GATA GPB-Int5 GPB-230 FY-265 HbS173
Status Code
CV - Coefficient of Variation of intensities exceeds recommended maximum LS - Low Signal: signal intensity below recommended minimum HB - High Background: exceeds recommended maximum IC - Indeterminate call Approved By: Signature: Name (Print):
Result
Ax AA AA BB BB BB BB BB AA BB BB BB BB BB AA BB AA AB AA AA BB AA AA AA BB Date: Title: Blood Group Phenotype DNA Analysis By Elongation - mediated Multiplex Analysis of Polymorphisms
Notes
LOOK!! L245V and G336C are homozygous for B
Interpretation of HEA Genotyping by DNA Analysis
Polymorphism Result Interpretation
RhCE L245V BB hr -B also expresses partial C RhCE G336C FYA/FYB GATA BB BB BB Very surprising.
Hmmm, OK. [Red cells from patients that are FY*B but carry the GATA polymorphism are phenotypically Fy b express Fy b neg. Because carriers of this single nucleotide polymorphism do on cell types other than erythrocytes, they are not at risk for anti-Fy b production.] 3(p65)
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Is Our Patient Remarkable?
Yes, this patient is remarkable. The 41 PRBC’s the patient was transfused didn’t cause any transfusion reactions. So we can deduce: The patient didn’t make anti-hr B , even thought the patient is hr B .
Or did make anti-hr B and the anti-hr B is clinically insignificant.
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What Does This Mean Our Patient?
• Our patient is rare in phenotype, and genotype but having made anti- E, -C, -Fya, and Jsa, locating antigen negative units should not be difficult.
• Patient’s Fyb is silenced • This would eliminate the need for transfusing phenotypically Fy(a-b-) donor units. If in the future we had to recommend phenotypically negative units, we can now recommend genotypically negative units Fy(a-b+).
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Conclusions
Genotypes differ from phenotypes.
Molecular testing helps supplement the limitations of serological techniques by using DNA to analyze and predict red cell phenotypes by providing genotype information. Genotyping is helpful for providing information for problematic serological cases with complex or incomplete/questionable results. Though this relatively new tool in the field of blood banking has not replaced serological testing, it continues to revolutionize and expand our knowledge of immunohematology.
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References
1. Roback JD, Grossman BJ, Harris T, Hillyer CD. Technical Manual. 17 th ed. Bethesda, Maryland: American Association of Blood Banks (AABB); 2011.
2. Harmening DM. Modern Blood Banking & Transfusion Practices. 6 th Philadelphia, PA: F A Davis Company; 2012.
ed. 3. Ness PM, Moulds JM. BeadChip Molecular Immunohematology, Toward Routine Donor and Patient Antigen Profiling by DNA Analysis. Springer Science+Business Media; 2011.
4. HEA BeadChip TM Package Insert. Warren, NJ: BioArray Solutions; 2012.
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Thank You for Your Time
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Questions
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