Stein Lectures Flashcards
What is FISH?
Fluorescence in situ Hyrbidization: it is a cytogenic technique where a specific DNA probe bound to a fluorescent or radioactive isotope is created to hybridize with a samples DNA in order to detmermine if that DNA exists in the host
What are the three basic types of FISH?
- Repeat sequences: usually derived from telomeres or centrosomes
- Single Copy DNA: usually isolated from a cloned DNA of a disease-causing gene or a fragment of DNA of known loction associated with a particular gene
- Chromosome painting: a combination of many unique fragments of DNA along a chromomse so that the entire chromosome fluoresces
What are contiguous Gene Syndromes?
regions in the genome with clusters of closely associated genes (when duplicated or deleted express a specific clinical symptom) whose normal functions are generally unrelated
What is VCFS?
Velocardiofacial syndrome: 2nd most common syndrome known to humans resulting from a 3 MB deletion on chromosome 22. There is a wide variation of effects including: hypotonia, short stature, learning disabilities, cardiac anomolies
What is William’s Syndrome?
It’s caused by a deletion of an Elastin (ELN) gene on chromososome 7, the symptoms include: blue sclera, gifted musical abilities, usually low IQ, Stellate Iris, renal anomalies, terrible math skills
What type of inheritance pattern do mitochondrial genes have?
Matrilineal, none of the mitochondrial genes are given by the father, however, some mitochondrial disorders could be X-linked or autosomal since mitochondria rely on some nuclear genes
What is homoplasmy?
When all of the mitochondria within a cell have the same genome, meaning they’re the same
What is heteroplamy?
When there are two or more different mitochondrial genomes present in a cell.
In order for a cell to display dysfunction there must be about 85% of mutant mitochondria expressed
What region of DNA is frequently used in forensics?
Hyperviable minisatellite regions
Why is mitochondrial DNA espcially resilient to long term degradation?
Because it is circular and their are multiple copies of it within each cell
How is maternal serum alphafetoprotein useful?
MSAFP levels (high/low) have been associated with fetal abnormalities. Alpha fetoprotein is a major plasma protein produced by the yolk sac during fetal development. Several factors need to be calculated before the effect of this measurement is determined
High=Open spina bifida
Low=Down Syndrome
When is ultrasound normally performed?
Around 18 weeks gestation
What can you gather from an ultrasound?
Verify viability
Detect a multiple pregnancy
Determine gestational age
Determine Sex
Identify some abnormalities (clefting, nuchal translucency, neural tube deftects)
What is alpha fetoprotein?
It is an albumin like protein produced by the fetal liver. It can cross the placenta into the maternal blood circulation.
What is the maternal Quad test?
A serum assay measuring four different chemical concentrations of key molecules involved in fetal development
What is cfpDNA?
cell free placental DNA. It is free floating DNA with placental/fetal origin. This can be analyzed to identify specific DNA sequences indicative of disease
What is amniocentesis?
It is an invasive prenatal screening procedure whereby a needle is inserted through the abdomen into the amniotic cavity and amniotic fluid is withdrawn for testing. Risk of fetal loss is 1/200.
usually performed 16-18 weeks