What does the FISH test look for?
the presence or absence of DNA on chromosomes
What does CMA do?
uses 1.8 million "normal" probes to analyze a genome for any variations
What does FISH stand for?
Fluorescent in situ hybridization
DNA methylation is carried out by which 2 mechanisms?
1) maintenance methylation 2) de novo methylation
What are copy number variations?
deletions or duplications of chromosomes
What does CMA stand for?
chromosomal microarray analysis
What does SNP microarray stand for?
single nucleotide polymorphism microarray
What test should be ordered before an SNP microarray and why?
chromosome analysis because this can diagnose common aneuploidies first
________ activity is necessary to preserve DNA methylation after every cellular DNA replication cycle.
What does DNA methylation analysis screen for?
1) Prader-Willi 2) Angelman Syndrome
Chromosome studies are performed concurrently with _____,
How does SNP microarray work?
it detects both copy number variation (deletions or duplications) and copy-neutral structural variants such as regions of homozygosity (ROH) and uniparental disomy (UPD)
Where does methylation occur?
at the C5 position of CpG dinucleotides
What are the steps to perform an SNP microarray?
1) hybridize DNA to bead chips 2) label with probes 3) scan with laser and interpret with software
What phase of the cell cycle does FISH use?
metaphase or interphase
What are the steps to perform a standard chromosome analysis?
1) examine at least 20 cells in metaphase 2) compile at least 3 karyotypes
What diseases did we learn about that are diagnosed with FISH? (6)
1) Prader-Willi 2) Angelman 3) 22q13 deletion syndrome 4) CML and ALL (leukemias) 5) Down Syndrome 6) 15q duplication
Why is SNP microarray used instead of a karyotype?
It can detect submicroscopic abnormalities, including microdeletions and microduplications
What phase of the cell cycle is used to perform standard chromosome analysis?
1) fix cells 2) add complementary fluorescent RNA probes 3) look at fluorescence under microscope, which tells if hybridization occurred and therefore the chromosome/location was present and where
What kinds of specimens are commonly used for cytogenetic studies? (4)
1) bone marrow 2) blood 3) tissues- lymph nodes, tumors 4) fluids- CSF, amniotic fluid
SNP microarray does not detect ______, _______, _______, or __________.
balanced rearrangements (i.e., inversions, translocations), heterodisomy, very low level mosaicism, or single nucleotide mutations/polymorphisms
What is analyzed in amniocentesis and chorionic villi sampling?
What is DNMT and what does it do?
DNA methyltransferase; it is the maintenance methyltransferase that copies DNA methylation patterns to the newly synthesized daughter strand
What are examples of copy-neutral structural variants?
1) regions of homozygosity 2) uniparental disomy
________ are performed concurrently with FISH testing,
Standard chromosome analysis is used to detect ___ (6 things).
Trisomies, Monosomies, Larger partial deletions, duplications, some translocations, inversions