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.