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25 Cards in this Set

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what is the goal of newborn screening?
early recognition of a disorder so that intervention will prevent or reverse the disease process
what is the goal of heterozygote screening?
to identify unaffected carriers of a disease gene who can then be given information about risks for having affected offspring and reproductive options
for which types of diseases is heterozygote screening normall performed?
autosomal recessive
when can standard amniocentesis be performed during pregnancy?
15-18 weeks
when can chorionic cillus sampling (CVS) be performed during pregnancy?
9-12 weeks
when can early amniocentesis be performed during pregnancy?
11-15 weeks
when can ultrasound be performed during pregnancy?
the entire time
when can fetal blood sampling be performed during pregnancy?
18 weeks
what are 5 reasons to perform prenatal diagnosis?
maternal age >35, previous child with chromosome abnormality, history of structural chromosome abnormality in one of the parents, family history of genetic defect diagnosable by biochemical or DNA analysis, and risk of neural tube defect
what are the drawbacks of genetic sequencing for direct genetic diagnosis?
it is expensive and does not guarantee detection of the mutation responsible for the disease in the family
what are 3 possibilities for a false negative in genetic sequencing for direct genetic diagnosis?
1) patient does not have a mutation in the tested gene, 2) patient has a sequence alteration that cannot be detected by sequence analysis, or 3) patient has a sequence alteration in a region of the gene not covered by the laboratory's test
for what does ASO stand?
allele specific oligonucleotides
what must be known to perform ASO?
the DNA sequence surrounding a mutation
which DNA sequences are used as probes in ASO?
the mutation sequence and the normal sequence
what is a dot blot? A reverse dot blot?
when the test DNA is spotted on a membrane and ASOs for mutation and normal types are added; when the ASOs are attached to the membrane and the test DNA is the probe
what is a disadvantage of ASO technique?
it is not useful to detect rearrangements of genes such as large deletions
which technique is used to identify gene expression profiles in cancer, for example?
microarray analysis
what is microarray CGH?
when microarray is used to identify loss and gain of genetic material
do microarrays usually use the dot blot of reverse dot blot principle?
reverse dot blot
what is not detected in microarray CGH?
balanced rearrangements or mosaicism for gain/loss of chromosomes or chromosomal segments
at what does indirect genetic diagnosis look?
DNA polymorphisms linked to the disease gene to determine whether an individual has inherited a chromosome containing the disease gene from his or her parent
what are 2 disadvantages to indirect genetic testing?
need to type multiple family members and possibility of recombination
what is presymptomatic testing?
testing of individuals who will develop the disease, if they carry the disease phenotype
do predictive tests deal with probabilities or certainties?
probabilities
does detection of mutations in a gene reveal the severity of the disease?
no