Study Genetic Testing Flash Cards

 
Pile Management Card
Genetic Testing

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Insurance
-GTests not covered
– If yes, those insurers will have access to results
Who investigated GT kits?
– US Government Accountability Office
GT Regulations
-none in US
– Categorized as services, not regulated by FDA
– Dubious claims
• no recommendations/counseling
Down Syndrome
• Trisomy 21
• Incidence increases with mom age
• Increased risk for certain medical
conditions
• Life expectancy dramatically improved over last decades (from 25-->60)
Tay‐Sachs Disease
• Inherited metabolic disorder
• Defect in enzyme hexosaminidase (Hex A)
• Infantile and late‐onset
– Infantile most common
– Severe retardation
• Affects Jews usually
• No treatment‐fatal
• Tests are enzymatic or genetic
Sickle Cell
• Anemic disorder
• Defective hemoglobin
• Autosomal recessive disorder
• Affects millions around the world
• affects mostly blacks
• Simple blood test‐ infants
Huntington’s Disease
• Degenerative brain disorder
• Autosomal dominant gene
• Presents 30‐50 years
• Disease symptoms vary
• Testing
– Predictive
– Confirmatory
– Prenatal
Type B Hemophilia
-Christmas disease, defect in clotting factor IX
Type A Hemophilia
-classical hemophilia, defect in clotting factor VIII
Duchenne Muscular Dystrophy
-affects voluntary muscles
• X‐linked recessive inheritance
• DMD gene encodes for Dystrophin‐ the largest gene to date
• Symptoms evident in infancy
• Testing
– Muscle sample‐ protein stain
– DNA sample‐ large deletions or
sequencing
Cystic Fibrosis
• Most common inherited disease among causcasians
• Disease due to defect in ion channel protein CFTR
-autosomal recessive
Charcot‐Marie‐Tooth
• common neuro disorder
• Onset is adolescence
-gradual progression, pain
• Not lethal, normal life expectancy
• many forms vary in severity
and symptoms
Breast Cancer
• Only 5‐10% of women have hereditary form
• BRCA1 & BRCA2
– increased chances with BRCA mutation
• Susceptibility only
• Need determined by family history
Hemophilia
• X‐linked recessive inheritance
• Hemophilia A or Hemophilia B
• Testing is done to identify women who are carriers or to diagnose fetuses during pregnancy
Sporadic
-late‐onset Alzheimers: most common
FAD
-early‐onset Alzheimers: develops before age 65
riluzole
-Riluzole is a drug used to treat amyotrophic lateral sclerosis
-still no cure for ALS
Amyotrophic Lateral Sclerosis
• ALS or Lou Gehrig’s disease
• Progressive neurodegenerative disease
– Muscle weakness, speech,
swallowing and breathing difficulty
• No treatment
– FDA approved drug riluzole
Guthrie test
a medical test performed on newborn infants to detect phenylketonuria
Phenylketonuria
Phenylketonuria (PKU)‐ increased level of phenylalanine in blood (enzyme deficiency)
– If untreated, severe retardation
– just need diet restrictions
– Guthrie test
What proteins can be tested for genetic problems?
• Proteins‐ testing restricted to enzymatic proteins, not valid for structural proteins
How is genetic testing done?
• Tissue sample is taken
• Proteins‐ testing restricted to enzymatic proteins, not valid for structural proteins
• DNA‐ molecular diagnosis
• Chromosomes
Alzheimer’s Disease
• Complex
• Two types‐ familial (FAD) & sporadic
• Apolipoprotein
– 3 common alleles: ApoE2, ApoE3, ApoE4
• Forensic testing
‐ uses DNA sequences to
identify an individual for legal purposes
– Victim identification
– Criminal involvement
– Relationships
• Predictive testing
‐ to detect gene mutations associated with disorders that appear after birth
– Presymptomatic: presence of mutation indicates individual will likely develop symptoms
– Predisposition: development of symptoms is likely but not certain
– Can influence life decisions
– Discouraged in children if no treatment is available
• Preimplantation testing
‐ a specialized technique that can reduce the risk of having a child w/ a genetic disorder
– aka preimplantation genetic diagnosis (PGD)
– Limited availability
– Not always possible
– $$$
• Prenatal testing
‐ detect changes in a fetus’s
genes or chromosomes before birth
– Amniocentesis, chorionic villi sampling
– May impose increased risk to fetus
– Specific mutations must be identified in parents
• Carrier testing
-to identify people who carry one copy of a mutation
– Reproductive choices
– Counseling and educational support
– Family testing
– Risk assessment for ethnic groups
• Diagnostic Testing
‐ to identify a specific genetic or chromosomal condition
– Symptomatic
– Medical management
– May have implications for family members
– May require more than one test
• Newborn screening
‐ genetic disorders that can be treated early in life
– Not intended for diagnosis
– Phenylketonuria (PKU)
Types of Genetic Tests
• Newborn screening
• Diagnostic testing
• Carrier testing
• Prenatal testing
• Preimplantation testing
• Predictive testing
• Forensic testing
• Genome scanning‐SNPs
• Genome Scanning‐ SNPs
– Can be used to predict how you’ll respond to certain drugs
– Useful for complex (multigenic) traits
– Some associated with risk of disease
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