GENETIC COUNSELING, TESTING & TREATMENT Flashcards
Specialized health care service provided by professionals known as genetic counselors
Primary aim: to help individuals &
families understand and make informed
decisions about genetic conditions that
may affect them or their offspring
GENETIC COUNSELING
- Health care professional with a master’s degree who can help patients & their families understand the inheritance pattern of a specific medical condition, evaluate the risk, & possibly navigate the path of genetic testing.
GENETIC COUNSELOR
Reasons to seek genetic counseling:
i. Family history of abnormal
chromosomes
ii. Elevated risk of single-gene
disease
iii. Family history of multifactorial
disease
iv. Family history of cancer
Focuses on assessing & discussing the risk of genetic conditions or birth defects in a pregnancy
PRENATAL GENETIC COUNSELING
Focuses on helping individuals understand their risk of developing certain genetic conditions that typically manifest in adulthood (cardiac, neurologic, & hematologic conditions)
GENETIC COUNSELING FOR ADULT-ONSET DISEASES
Medical tests that analyze an individual’s DNA to identify changes in specific genes/chromosomes
GENETIC TEST
GENETIC TESTS THROUGH HUMAN
LIFE CYCLE
1) Preconception and Prenatal
2) Newborns
3) Children
4) Adults
5) Posthumous
- “GAMETE DONOR SELECTION
BASED ON CALCULATIONS” - Computer program that predicts the results of meiosis in the gametes of an individual
- Analyzes possible gamete phenotypes
of the “recipient” (presumably a woman) & a “plurality of donors” (presumably men), considering penetrance & epistasis - “Hypothetical offspring” Also detects if potential parents are
close blood relatives
PRECONCEPTION AND PRENATAL
- Sperm are labeled with fluorescent
markers: X-bearing sperm cells glow
more intensely than Y-bearing sperm
because the X chromosome is so much
larger. - Sperm are collected & separate them
into fractions that are enriched for X- bearing or Y-bearing cells, to attempt to
conceive a girl or a boy, respectively
FLOW CYTOMETRY
It identify genetic conditions or
disorders early in life to enable timely medical intervention, treatment, or
management.
GENETIC TESTING FOR NEWBORNS
analytical chemistry technique that detects abnormal metabolites
MASS SPECTOMETRY
aims to detect certain genetic, metabolic/congenital conditions shortly after birth, even before symptoms become apparent.
DNA TESTING
Involves analyzing a child’s DNA to identify genetic variations, mutations, or abnormalities that may be associated with specific medical conditions or
genetic disorders.
GENETIC TESTING FOR NEWBORNS
Detects small deletions, duplications, & other CNVs associated with certain
phenotypes.
CHROMOSOMAL MICROARRAY ANALYSIS
Diagnoses unrecognized syndromes/ atypical cases; family comparisons
distinguish de novo from inherited
mutations in children.
EXOME SEQUENCING
- Genetic testing after death
- Involve examining DNA samples
obtained during an autopsy, tissue
preservation, or using stored biological
samples from the deceased person
POSTHUMOUS GENETIC TESTING
- A service that allows individuals to obtain information about their genetic makeup directly from a company w/o involving a health care professional/medical provider
Marketed directly to customers via television, print advertisements, or the Internet, & the tests can be bought
online or in stores.
DIRECT-TO-CONSUMER GENETIC TESTING
Certain Individuals possess a genetic advantage that predisposes them to excel
in specific sports or physical activities.
TEST FOR INBORN ATHLETIC ABILITY
Examines an individual’s genetic makeup to
provide personalized dietary recommendations
NUTRIGENETICS TESTING
Focus on understanding how an individual’s genetic makeup
influences their for medications
PHARMACOGENETIC & PHARMACOGENOMIC TETSING
detects a variant of a single gene that affects drug metabolism
PHARMACOGENETIC TEST
detects variants of multiple genes/gene expression patterns that affect drug metabolism
PHARMACOGENOMIC TEST
AKA drug repositioning/drug
reprofiling
Process of identifying new therapeutic
uses for existing drugs that were
originally developed for different
indications
Less costly than developing new drugs
DRUG REPURPOSING
Delivers working copies of genes to specific cell types or body parts, Typically as part of modified viruses that function as carriers (vectors)
GENE THERAPY
Alters the DNA of a gameteor
fertilized ovum, so that all cells of
the individual have the change & the correction is heritable, passing to offspring
GERMLINE GENE THERAPY
Corrects only the cells that an illness affects & is nonheritable, in which the recipient does not pass the genetic correction to offspring, unless the cells that give risetogametes are inadvertently altered
SOMATIC GENE THERSPY
COMMON SITES OF
SOMATICGENETHERAPHY
- Can be genetically altered to secrete proteins into the circulation
endothelium
COMMON SITES OF
SOMATICGENETHERAPHY
- Immature muscle cells given healthy dystrophin genes may treat muscular dystrophy.
MUSCLE
COMMON SITES OF
SOMATICGENETHERAPHY
- To treat certain inborn errors of
metabolism, only 5% of the liver’s
10 trillion cells need to be
genetically altered.
LIVER
COMMON SITES OF
SOMATICGENETHERAPHY
-
COMMON SITES OF
SOMATICGENETHERAPHY
- Gene therapy can reach damaged
lungs through an aerosol spray. Enough cells would have to be reached to trat hereditary emphysema (alpha-1-antitrypsin
deficiency) or cystic fibrosis
LUNGS
COMMON SITES OF
SOMATICGENETHERAPHY
- Gene therapy can target skin cells
to treat certain skin disorders, such as epidermolysis bullosa
SKIN
- Cells are altered outside the body
& then infused into the
bloodstream through a vein
EX VIVO GENE THERAPY
COMMON SITES OF
SOMATICGENETHERAPHY
- “In the living body”, the gene & its
vector are introduced directly into
the body, such as through a
catheter inserted & snaked to the
appropriate organ
IN VIVO GENE THERAPY
amplify specific DNA sequences from a DNA sample, generating large amounts of the target gene for further analysis, manipulation, or delivery into target cells
PCR
- Manipulation & combination of DNA from different sources to create new DNA sequences that encode therapeutic genes or their modified versions.
RECOMBINANT DNA TECHNOLOGIES
Had severe combined immune deficiency due to adenosise deaminase (ADA) deficiency
ASHANTI (“ASHI”) DESILVA
Had ornithine transcarbamylase
(OTC) deficiency & could not
make a liver enzyme required to
break down dietary proteins
Trillion adenoviruses carried
functional human OTC genes
through a tube into his liver
Viruses entered not only the
hepatocytes as intended, but also
macrophages that alert immune
system
JESSE GELSINGER
Not only delivers a gene to a specific
part of the genome, but can replace a
gene, remove a gene, or add a gene, &
do so in multiple places or insert, correct, or delete multiple genes
Can be combined with genome
sequencing to engineer an animal
model of a family’s inherited disease, to
refine diagnosis & reveal how the
symptoms arise (family with thoracic
aortic aneurysm & dissection)
CRISPR-CAS9 IN DIAGNOSIS AND TREATMENT
- Reactivating the quiescent globin genes can treat the disease
- Use of induced pluripotent stem cells (iPS cells)→ CRISPR-Cas9 replaces 1sickle cell mutation with a wild type of
the copy of the beta globin gene - Use CRISPR-Cas9 to silence a gene that normally switches fetal hemoglobin production off after birth
SICKLE CELL DISEASE
- Enzyme glucocerebrosidase is
deficient or absent - Due to little/no enzyme: buildup of
substrates lysosomes swell →
bursting cells - Symptoms: enlarged spleen & liver, bone pain, & deficiencies of blood
cells - Variable in age of onset, severity
of symptoms, & rate of
progression
TYPE 1 GAUCHER DISEASE
