Chap 22 Flashcards
Genetic Testing and Treatment (25 cards)
Genetic counselor
Health care professional helps patients and their families navigate the path of genetic testing.
Genetic counseling
- Pediatrics, and prenatal care.
- Branched into specialties such as cancer, cardiovascular disease, neurology, hematology and ophthalmology.
Genetic Screening and Testing
Identifying mutations can help in diagnosis and choosing treatments
Preimplantation genetic diagnosis
- Focus on disease
- Earliest test done on embryo following in vitro fertilization
Prenatal Testing
- Chorionic villus sampling
- Amniocentesis
- Maternal serum markers - Noninvasive prenatal testing of cell-free fetal DNA done later in pregnancy
Genetic Testing of Newborns
- Screening identifies infants at high risk of having certain
genetic diseases that are “actionable” - DNA testing
- Mass spectrometry detects atypical metabolites
Genetic Testing of Adults
- To detect increased risk of developing certain cancers
- Tests can identify carriers of more than 1,000 recessive disorders.
Treating Genetic Disease
- Removing an affected body part
- Replacing an affected body part or biochemical with material from a donor
- Delivering pure, human proteins derived from recombinant DNA technology
- Refolding correctly a misfolded protein
- Blocking gene expression (gene silencing)
- Using gene therapy to add wild type alleles without removing mutant alleles
- Using gene editing and genome editing to replace, delete, or add alleles
Protein-Based Therapies
Adding digestive enzymes to applesauce for a child with disease. (CF, hemophilia)
3 Type of Protein-Based Therapies
- Enzyme replacement therapy
- Substrate reduction therapy
- Pharmacological chaperone therapy
Enzyme replacement
and substitution
therapy
Recombinant human enzyme infused to compensate for deficient
or absent enzyme
Substrate reduction
therapy
Oral drug reduces level of substrate so enzyme can function more effectively
Pharmacological
chaperone therapy
Oral drug binds misfolded protein, restoring function
Gene Therapy
Delivers working copies of genes to specific cell types or body parts, typically aboard modified viruses
Germline gene therapy
Gamete or zygote alteration; heritable; not done in humans; creates transgenic organisms
Somatic gene therapy
Corrects only the cells that a disease affects; not heritable
Ex vivo gene therapy
applied to cells outside of body that are then returned
In vivo gene therapy
applied directly to an interior body
part.
most invasive
Delivery of Gene Therapy
- Using viral vector that already remove the defective gene and adding corrective gene
Sites of Gene Therapy
- Endothelium: can secrete into bloodstream
- Muscle: good blood supply
- Liver: can regenerate
- Lungs: aerosol spray
Adenosine deaminase (ADA) deficiency.
- The first gene therapy
- A form of severe combined immune deficiency disease
- Absence of ADA enzyme causes build up of deoxyATP
- Destroys T cells, thereby causing susceptibility to
infections and cancer.
Strimvelis
Gene therapy that uses a patient’s own haematopoietic stem cells, the precursor cells for blood and immune cells,
to correct ADA mutation.
Sickle Cell Disease
Single-base mutation in beta subunit causes sickle cell disease
Sickle Cell Disease treatment
- Using hematopoietic steam cell
- Using viral vector carrying modified beta-globin gene
