Genetic Mutations and Gene Therapy

• Most genetic mutations result in abortion because of the severity of the mutations.
• Genetic disorders are diseases caused by a gene malfunction.
• Complex traits are common diseases caused by multiple genes interacting.
• A major goal of modern genetics is to identify genes responsible for contributing to human diseases.
• Genetic disorders result from mutations, which most often come from changes in the DNA sequence, chromosome number, or structure.
• Humans have 23 pairs of homologous chromosomes, with 23 from each parent, totaling 46.
• Gene therapy corrects abnormal genes responsible for disease development.
  • It removes or replaces mutated DNA to slow or stop disease and is a form of genetic engineering that permanently introduces altered genes into a cell, tissue, or organism.
• Eric Olsen used Cas-9 (CRISPR) as gene therapy to bypass the stop codon in genes, allowing dystrophin protein to reappear and prevent Duchenne muscular dystrophy.
• A karyotype is a photograph of a cell's complete set of chromosomes with each homologous chromosome paired.
• Homologous chromosomes are not identical but are the same length; one comes from each parent.
• There are 22 autosomal chromosomes and 2 sex chromosomes.
• Larger structures carry more genes.
• Autosomes are non-sex chromosomes (homologous) that are exactly alike in length, shape, and genes.
• Autosomal chromosomes are numbered 1-22 from biggest to smallest.
• Sex chromosomes are the 23rd pair.
• Sex chromosomes determine gender: XX for female, XY for male, and sperm determines the gender.
• Chromosomal abnormality refers to any change in chromosome number or structure.
• Mutations can affect entire chromosomes or individual genes.
• Large changes can be analyzed by karyotyping, while small changes cannot be visualized by karyotype but can be analyzed by molecular techniques.
• Locus is the physical location of a gene on a chromosome, and a diploid cell can have two alleles.
• Humans are diploid as a normal state, containing two complete sets of chromosomes, one from each parent.
• Structural changes include inversion and translocation, where a chromosome piece breaks off and reattaches to a different chromosome, or chromosomes exchange pieces.
• In gene therapy, doctors remove stem cells from a patient to start, which are unique, unspecialized cells that can make identical copies of themselves for long periods.
  • They are mixed in a dish with a viral vector carrying the healthy gene.
• After freezing and testing for the healthy gene's presence, genetically modified cells are injected back into the patient to replicate, spread, and produce the desired protein.

Genetic Disorders

• Recessive (aa) occurs when both parents are heterozygous (Aa).
  • ¼ is homozygous dominant
  • 2/4 are carriers
  • ¼ are affected with a 25% chance
• Genetic carriers of a disorder carry the disorder allele but do not have the disease.