Genetics,gene-env interacts Sp25-TO POST

Genetics in Public Health & Gene-Environment Interactions

Overview of Genetics

• Genetics plays a crucial role in public health, affecting disease susceptibility and severity.

• Focus on gene-environment interactions that contribute to health outcomes.

Key Concepts in Genetics

Definition of Genes

• Genes are composed of DNA and serve as the units of inheritance.

• Each gene encodes for inherited traits that vary among individuals.

Structure of DNA

• DNA has a sugar-phosphate backbone and contains four nucleotide bases:

  • Adenine (A)

  • Guanine (G)

  • Cytosine (C)

  • Thymine (T)

Transcription and Translation

Process of Protein Synthesis

• The flow of genetic information:

  • Gene → mRNA transcript → Protein

• Translation involves reading mRNA nucleotide bases in groups of three, called codons.

• Each codon specifies an amino acid or signals the start/stop of protein synthesis.

Mutations

• Mutations are changes in genes that can produce variations in proteins.

• Most mutations are silent (no effect), but some can be harmful or beneficial.

Types of Mutations

Effects of Mutations

• Genetic mutations can alter:

  • How proteins are made

  • When they are made

  • Functionality of the proteins

• Precision in DNA replication is essential, with errors occurring approximately 1 in 10 billion times.

• Genetic disorders may arise from such mutations.

Examples of Genetic Disorders

Specific Disorders

• Sickle Cell Anemia: Caused by two copies of the hemoglobin S gene, leading to sickle-shaped red blood cells and various health complications:

  • Anemia and fatigue

  • Organ damage

  • Increased risk of infections and strokes

• Sickle Cell Trait: One copy of the hemoglobin S gene, generally asymptomatic but may affect athletes.

• Cystic Fibrosis: Results from a defective gene, causing mucus blockages and potential infections in vital organs.

Sex-Linked Genetic Disorders

Chromosomal Diseases

• The 23rd pair of chromosomes determines gender:

  • XX for females

  • XY for males

• Color blindness is an example of a recessive, sex-linked disorder linked to genes on the X chromosome.

Gene-Environment Interactions

Definition and Examples

• Gene-environment interaction occurs when a specific genotype increases disease risk in the presence of certain environmental factors.

• Example: Individuals with light skin and red hair in sunny areas are at higher risk for skin cancer.

Drug Metabolizing Enzymes (DMEs)

• DMEs play a role in how drugs are metabolized, affecting therapeutic outcomes.

• CYP2D6 is a critical DME, influencing the metabolism of many prescription drugs.

  • Variation among individuals: poor, extensive, and ultra-rapid metabolizers exist within populations.

Gene-Environment Interaction in Drug Response

Specific Cases

• Some drugs are inactive until metabolized (e.g., codeine to morphine via CYP2D6).

• Understanding individual metabolic profiles is key in prescribing medications to avoid adverse effects or ineffective treatment.

Example of Gene-Environment Interaction

Alcohol Metabolism

• Alcohol is metabolized primarily in the liver:

  • ADH converts ethanol to toxic acetaldehyde.

  • ALDH metabolizes it to less toxic acetate.

• Atypical forms of ADH and ALDH2 genes lead to rapid acetaldehyde buildup in specific populations, causing flushing reactions.

Impacts of Gene-Environment Interactions

Additional Considerations

• Individuals with genetic variants may respond differently to environmental factors, affecting disease risk and treatment.

• Example: Individuals with certain genetic markers may have heightened risk for cancers based on dietary intake (e.g., red meat).

Questions & Engagement

• Class questions regarding the lecture content, quizzes, or exams can help clarify understanding and application of genetics in public health.