Patho: Genetic Influence in Disease - Lecture Notes
Introduction
- Objective: Understand the genetic influence in diseases.
- Outline: Weekly prep review, basic genetics, gene function, genetic disorders.
Basic Genetic Concepts
- Gene Definition: Segment of DNA composed of nucleotide bases.
- DNA Location: Found in the nucleus of most cells; tightly coiled within cells.
- Gene Function: Codes for protein synthesis, which underpins bodily processes and features (e.g., eye color, blood type).
Gene Mutations
- Impact: Mutations alter protein synthesis, potentially leading to dysfunctions (e.g., lactase deficiency).
- DNA Structure: DNA can form chromosomes; chromosomes are like 'pearls on a string'.
Chromosomes and Genes
- Chromosome Count: Humans have 46 chromosomes (23 pairs - 22 autosomal, 1 sex pair).
- Alleles: Partner genes on chromosome pairs that code for the same trait, can be dominant or recessive.
- Genotype: Combination of alleles (homozygous dominant, homozygous recessive, heterozygous).
- Phenotype: Observable characteristics determined by genotype.
Inheritance
- Punnett Square: Tool to predict genetic trait inheritance.
- Genotype Types:
- Homozygous Dominant: Two dominant genes.
- Homozygous Recessive: Two recessive genes.
- Heterozygous: One dominant and one recessive gene.
Genetic Disorders
- Categories:
- Mitochondrial
- Multifactorial
- Chromosomal
- Single Gene
Mitochondrial DNA Disorders
- Prevalence: Rare, usually not covered extensively.
Multifactorial Genetic Disorders
- Combination of factors: Environmental and genetic (e.g., certain cancers, hypertension, diabetes).
Teratogenic Disorders
- Definition: Caused by external influences (e.g., drugs, radiation) during fetal development.
- Examples: Fetal alcohol syndrome, thalidomide effects.
Chromosomal Disorders
- Alterations in Number: e.g., Down Syndrome (Trisomy 21).
- Alterations in Structure: e.g., Philadelphia chromosome.
Single Gene Disorders
- Inheritance Patterns: Autosomal dominant, autosomal recessive, sex-linked.
Autosomal Recessive Disorders
- Example: Sickle Cell Anemia
- Cause: Mutated recessive gene affecting hemoglobin.
- Phenotype: Anemia, SOB (shortness of breath), ischemic pain.
- Carriers: Heterozygous individuals may have mild symptoms (sickle cell trait).
Autosomal Dominant Disorders
- Example: Polycystic Kidney Disease (PKD)
- Cause: Dominant gene causing cystic kidney cells.
- Symptoms: Enlarged kidneys, hematuria, proteinuria.
Recombinant DNA
- Definition: Artificially combining DNA from different sources.
- Applications: Production of human growth hormone, insulin, clotting factors, clot busters.
Note: Genetic disorders are complex, and the lecture simplifies them for basic understanding. Recombinant DNA is a rapidly advancing field in genetic engineering.