Genetics part 3 Flashcards
Family History:
Genetic screening tool/health analysis
personalized approach to disease prevention
recognize patterns of inheritance
Identify genetic syndromes
assess and eval of risk
Pedigree:
Graphic rep of family’s health and genetic relationships
Illustration of biologic and social relationships
Preferred method of organization
Genetic testing:
Genetic testing is the analysis of DNA, RNA, chromosomes, proteins, protein metabolites to identify heritable diseases in genes and chromosomes
Oversight:
Labs doing genetic testing must be certified under the clinical lab improvement act
Sample tissue:
Most commonly used samples are epithelial cells from buccal swabs or saliva
Blood samples require special tubes to prevent clotting and inhibit DNA breakdown by enzymes
Saliva collection requires polypropylene tubes
PCR Amplification:
Copying small segments of DNA -fast inexepensive
steps include denaturing (separating) thru heating followed by enzymatic building of new DNA
leads to 1 billion copies of DNA
Cell Free DNA cfDNA
-Small piece of DNA circulating in the blood after cell lysis thru apoptosis
-Fetal DNA from the placenta can mix with maternal
-cfDNA and can be used for per natal testing
-collected from plasma or urine
-non-invasive
-Non invasive prenatal testing helps find fetal blood type, fetal sex determination assoc with sex-linked disorders, chromosomal aneuploidy detection and diagnosis of single gene disorders
-less expensive
Circulation Tumor (ctDNA)
Cancer cells have rapid turnover as cell die they shed tumor specific DNA Strands
Ct DNA strands are much shorter than the cf DNA shed by other cells
Reports indicate the stability of the tumor (higher level= more cancer present)
Helps with individualized treatment selection and detect changes that may lead to resistance to treatment
Identify recurrence of cancer after remission
Diagnostic Testing:
Done to confirm or rule out a particular diagnosis from a symptomatic patient
Some clinical tests better than genetic testing (CF sweat chloride test)
Predictive Testing:
Done to asymptomatic individuals who want information about their risk of developing a disease in the future
Positive predictive tests indicate the individual will develop the disease tested for at some point in the future (Huntington’s disease)
Pre-dispositional Testing:
Testing is done when having a gene variant increases the likelihood that a person will develop a genetic disease
Carrier Testing:
When individuals have a family members affected by a heritable disease (they aren’t affected)
Inconclusive Testing:
Individual has a variant of a gene that hasn’t been specifically linked to the disease in question
High risk monitoring should be put in place
Mutation databases such as ClinVar can be used to determine if the DNA sequence represents
DNA Sequencing:
Analysis of bases in a length of DNA
Most common practice is reviewing sequence of nucleotides in the region of the DNA that codes for a protein
Results shown in electropherogram
Cytogenic Testing:
-Evaluates entire chromosomes for variations in structures or numbers (cancer/infertility)
-Cells cultured and arrested in metaphase (cell division), stained, and reviewed for placement of centromere and banding patterns
-Result is a karyotype
