MLT1308 Lecture 1 GENETICS
Page 1: Introduction
MLT1308 Lecture 1: Genetics and Transfusion Science
Learning Objectives: 2.1 – 2.6, 4.4
Competencies: CSMLS 2.01 and MLPAO Competency
Page 2: Transfusion Medicine
Definition: Medical practice involving procurement, processing, and distribution of blood/blood components.
Involves testing patient samples to ensure safe transfusions.
Critical and potentially dangerous aspect of laboratory science.
Components include immunohematology testing and blood banking.
Page 3: Immunohematology
Definition: Study of immune responses to blood components; specifically antigen-antibody reactions.
Essential for pre-transfusion testing to avoid immune reactions during transfusions.
Conducted in hospital labs and private labs.
Page 4: Blood Banking
Definition: Procedures for collecting, storing, processing, and distributing blood components.
Canadian Blood Services (CBS) ensures viability of donated blood before use in transfusions.
Pre-transfusion testing checks compatibility of blood for patients.
Page 5: Overview of Transfusion Medicine
Alternative names: "TM", "Transfusion", "Blood Bank".
Involves multiple tasks:
Testing patient blood (ABO/Rh, Antibody screening, Identification)
Pre-transfusion testing and managing transfusion reactions
Donor blood testing conducted by CBS
Assigning and issuing blood products and maintaining inventory
Participating in trauma protocols.
Page 6: Roles of Laboratory Staff
Essential collaboration among laboratory staff to save lives.
MLAs: Handle blood collection following proper specimen requirements.
MLTs: Conduct blood analyses for compatibility and safety.
Page 7: Basics of Immunology and Genetics
Transition into fundamental concepts of immunology and genetics necessary for testing methods.
Page 8: Antigens
Definition: Substances stimulating antibody formation; large proteins/polysaccharides on cell surfaces.
Found on viruses, bacteria, fungi, blood cells, etc.
Over 230 red cell antigens on red blood cells (RBCs).
Page 9: Antibodies
Develop in response to antigens; present in plasma or serum.
Specific to the antigen they interact with, tested in plasma using EDTA tubes.
Page 10: Blood Sample
Components: Buffy coat contains white blood cells and platelets.
Antigens are located on the RBC membrane.
Page 11: Antigens & Antibodies
ABO Antigens: Determine blood type; presence of antibodies depending on the blood type.
Hundreds of antigens on RBCs; inherited from parents.
Page 12: Genetics
Definition: Gene - the basic unit of inheritance; located on chromosomes (23 pairs in humans).
One chromosome from mother, one from father.
Page 13: Alleles
Genes have specific locations (loci); different forms are called alleles.
Inheritance patterns depend on which alleles are passed from each parent, influencing expression.
Page 14: Inheritance Patterns - Dominant
Dominant traits expressed if inherited from one parent.
Example: Brown eye color - needs only one dominant allele to be expressed.
Page 15: Inheritance Patterns - Recessive
Recessive traits expressed only if inherited from both parents.
Example: Blue eye color - needs two recessive alleles.
Page 16: Inheritance Patterns - Co-Dominant
Both alleles expressed equally; neither masks the other.
Example: Blood type AB expresses both A and B antigens.
Page 17: Phenotype vs Genotype
Phenotype: Observable traits.
Genotype: Actual genetic makeup (e.g., BB, Bb, bb).
Page 18: Generational Phenotype and Genotype
First Generation: Grandparents express phenotype bb and BB;
Second & Third Generations: Parents with Bb; Grandchildren phenotype variations.
Page 19: Inheritance Patterns - Homozygous
Homozygous: Identical alleles for a trait; recessive traits require homozygous expression.
Page 20: Inheritance Patterns - Heterozygous
Heterozygous: Different alleles.
Dominant allele masks recessive; both alleles expressed if co-dominant.
Page 21: Gregor Mendel
Mendel's studies on sweet pea plants established foundational concepts of heredity and genetics.
Studied traits such as flower color to determine inheritance patterns.
Page 22: Mendelian Traits
Visual representation of Mendel’s traits in pea plants (Red: RR, White: rr).
Page 23: Mendel's Laws - Independent Segregation
One gene passed from each parent; segregation allows for independent transmission of genes.
Page 24: Mendel's Laws - Independent Assortment
Genes on separate chromosomes are inherited independently; mixes genetic traits in offspring.
Page 25: Punnett Squares
Tool to determine phenotype probabilities from genotypes based on Mendel’s laws.
Page 26: Drawing Punnett Squares
Initial setup for analyzing inheritance using Punnett Squares.
Page 27: Filling in Punnett Squares
Placement of parental genes into the squares; denotes inheritance probabilities for offspring.
Page 28: Probability in Punnett Squares
Each square represents a probability of combinations being inherited (e.g., RR, Rr, rr).
Page 29: Results of Crosses
Example: Offspring phenotype determined; all red from red x white cross. Dominance highlighted.
Page 30: Result Interpretation
Reiteration of the dominance of red gene over white in flower color.
Page 31: Second Generation Crosses
Cross Rr with Rr to produce probabilities for the next generation.
Page 32: Filling in Second Generation Punnett Squares
Continuing the crossing process with proper allele notation.
Page 33: Analyzing Outcomes
Probabilities for offspring genotypes and phenotypes established (RR, rr, Rr).
Page 34: Summary of Flower Color Combinations
Phenotypic breakdown showing dominance and ratio of red to white flowers in subsequent generations.
Page 35: Inheritance Odds
Consistent chance of phenotype expression persists with every offspring event.
Page 36: Recap of Key Concepts
Fundamental properties of antigens, antibodies, genetics, and their impact on traits summarizing their significance in transfusion medicine.
Page 37: Recap Overview
Antigens are proteins on RBCs; antibodies in plasma; genes determine traits on chromosomes.
Page 38: Recap of Genetic Concepts
Dominant and recessive gene functions; co-dominance; definitions of phenotype and genotype.
Page 39: Genetic Definitions
Clarified terms for homozygous and heterozygous traits; Mendel's experiments in genetics.
Page 40: Mendel's Laws Recap
Law of Independent Segregation and Assortment clarified; use of Punnett Squares for offspring probabilities highlighted.
Page 41: Blood Group Systems
Inheritance of RBC antigens follows Mendelian principles; categorized into blood group systems.
Page 42: ABO Blood Group System
Determines blood type based on A and B antigens; established by Karl Landsteiner.
Page 43: ABO Inheritance Patterns
Three alleles in the ABO group allow for multiple combinations leading to different blood types.
Page 44: Functional Expression of ABO Genes
Explanation of how inherited A, B, and O genes lead to corresponding antigen expressions on RBCs.
Page 45: ABO Dominance Hierarchy
Analyzes the relationship between A/B and O antigens through dominance and recessive behavior.
Page 46: ABO Antigen Expression Summary
Breakdown of antigens associated with phenotypes in the ABO blood group system.
Page 47: Punnett Squares in ABO Genetics
Analyzes genotypes of parents within the ABO system, elaborating on probabilities of offspring traits.
Page 48: Probability Outcomes in ABO Crossing
Examples showing percentages of resulting blood types and expressions based on parental genotypes.
Page 49: Further ABO Crossing Examples
Additional example pairings and potential offspring outcomes in ABO inheritance.
Page 50: Other Blood Group Systems
Exploration of additional blood group systems outside of ABO (e.g., MNS, Rh, Kell, Duffy, Kidd).
Page 51: Agglutination Reactions
Testing for antigens through agglutination reactions; antibodies used to identify specific antigens by binding, causing clumping.
Page 52: Dosage Effect in Blood Group Systems
Review of how homozygous and heterozygous genotypes influence antigen expression during testing.
Page 53: Example of Dosage in Gene Inheritance
Illustration of dosage impact using specific alleles (e.g., MN) on agglutination responses.