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blood group systems

one or more antigens with a single gene or complex of two or more closely linked homo genes, genetically discrete, variations re ID, sequenced and confirmed for phenotype

dna

in chromosome of each cell, replicated by mitosis (somatic) or meiosis gametes

antithetical

antigens produced by opposite alleeles (Kp^a and Kp^b)

polymorphic

multiple alleles at a single locus

recessive genes

expressed only when inherited by BOTH parents

codominant

queal expression of 2 diff alleles (blood groups)

amorph genes

do not express a detectable product (O gene)

mendelian principles- independent segregation

one gene from each parent passed to offspring in a predictable pattern, applied to blood group ag inheritance

mendelian principles- independent assortmant

different genes are separated creating a mixture of genetic material, different blood group systems inherited separately, does not include linkage and cross over

linkage

2 genes close in proximity are inherited together (haplotype), more common than unlinked genes= linkage disequilibrium

Xg genes

on X chromosome not autosomes, father passes to all daughters not sons, mother passes to all

phenotype

determined by hemagglutination of rbc ag using antisera, no agglutination with anti-A or B = type O blood

genotype

determined by molecular tech or family studies, A phenotype could be A/A or A/O

dosage effect

variation in ag expression due to number of alleles present, homo- double, hetero- single

phenotype calculation

predicts the number of compatible units

multiple ag negative frequencies of multiple traits inherited independently = amount of population neg for those ag, 1 to _ units compatible

units needed / ag neg frequency decimal

hardy-weinberg formula

calculated the gene frequencies that produce a trait, p + q = 1, AA= p², Aa= 2pq, aa= q²

molecular genetics- transplantation

HLA antigen-level and allele-level typing for HPC and organ transplants or Engraftment studies for HPC transplants

molecular genetics- transfusion

Red cell typing in multiply transfused patients, Determine blood type when DAT is positive, Complex Rh genotypes / weak D expression, Screen for ag-negative donor units when antisera is unavailable, Donor ag screening for prevention of alloimmunization

molecular genetics- HDFN

determine parental RhD zygosity, type fetal blood

molecular genetics- relationship testing

Establish paternity and legal relationships for immigration

PCR

rapidly and precisely multiplies specific dna sequences, denature dna at hot temp, cools and prime anneals to specific area, temp rises and rna polymerase synthesizes new dna

pcr hla typing procedure- sequence specific primers SSPs

primers in tray at low resolution id ag level, high levels define specific alleles of ag, replicate, amplified dna (amplicons) are assessed by gel electrophoresis

pcr hla typing procedure- sequence specific oligonucleotides SSOs

primer for each locus (A, B, C, DR, DQ, DP) in separated wells, replicate, denature and hybridized, dna probe analyzes with a flow cytometer

pcr hla typing procedure- sequence based typing SBT

high resolution allele level typing, primers similar to SSO, chain termination (sanger sequencing), nucleotide and amino acid sequences corresponding to each allele are analyzed

pcr hla typing procedure- short tandem repeats STRs

2-5 bp or DNA repeated 4-50x are amplified to determine percent of engraftment, dna sequence differences between donor and recipient (polymorphisms) give percent of dna from donor in a stem cell recipient using the chimerism evaluation

BeadChip tech

on a substrate slide oligonucleotide primers attached to colored silica beads and bind amplified and digested DNA, computers determine which primers have attached

Landsteiner law

healthy individuals possess ABO ab to the ABO group ag ABSENT from their rbc

ABO ag

intrinsic to membrane or soluble in body fluids, detected in embryo 5-6 weeks, newborns have partially developed fewer ag, full expression by 2-4 years

H gene vs Se

controls the presence or absense of ABH ag on rbc membrane vs in secretions

H Se ABO gene

H and h (amorph), Se and se (amorph), A B and O

oligosaccharide chain

precursor structure for rbc ag like A B H, attached to a protein or lipid acrrier molecule

H ag

codes for glucosyltransferase to transfer L-fucose to the terminal sugar of the oligo chain, the foundation for A and B ag, most on O groups

A ag

codes for transferase adding N-acetylgalactosamine to terminal sugar of H ag

B ag

codes for transferase adding D-galactose to the terminal sugar of H ag

A1 and A2 subgroups

both react strongly with anti-A, 8-% are A1 (branched)

rare A subgroups if

weak or no agglutination with commercial anti-A and anti AB, anti-A1 is present, or anti-H causes strong reaction

importance of subgroup ID

if missed in a donor could give wrong blood to patient

ABO antibodies

non-rbc stimulated (naturally occur), produced by exposure to A and B like ag, detected by 3-6 months, titers reach max at 5-10 years old then decrease with age

anti-A1 ab

produced by A subgroups, specificity to the A1 ag, no aggl with A2, not clinically sig, can cause incompatibility crossmatches on IS testing

rbc transfusion

ABO identical or compatible, must be ID for whole blood, AB is universal recip

plasma transfusion

ABO identical or compatible, process is reverse of RBC, AB univers donor, O univer recip

ABO discrepancies

forward and reverse contradict happens when agglu weaker than expected, missing reaction, extra reactions or ag

extra ag

A with acquired B- group A sugar altered by deacetylating enzyme resembling B and cross reacting with anti-B

B(A)- like acquired B but actually B

polyagg- hidden ag in rbc exposed and reacts with sera

nonspecific aggregation- rouleaux (too much serum protein), wharton’s jelly (gel tissue in cord blood)

missing or weak ag

leukemia or hodgkind disease can show weakened A and B ag expression, check patient diagnosis and transfusion history, repeat anti-A,B to enhance subgroup

mixed field reaction

contain both agglu and unagg cells, due to 2 cell population O with A B or AB, bone marrow and stem cell transplants, A3 phenotype, Tn-polyagglu rbc

extra ab

cause extra agglu reacting in reverse testing, due to Anti-A1, cold alloab and autoab, rouleaux (false pos agglutin)

fixing rouleaux

incub, centrifuge 1 min, remove serum and replace with saline, cenrofuge for 15 sec, resuspend cell button, neg = rouleaux, agg= true agglu

bombay phenotype

no H ag (hh), amorph creating little or no production of L-fucosyltransferase, labeled group O bc no ag on rbc, serum has anti-ABH, cannot donate bc H ag is actually present unless autologous or rare

secretor status

two alleles genes at this locus Se (H substances in saliva) and se, H is converted to A or B by glycosyltran, 80% of population are secretors (SeSe or Sese)