Lab tests Flashcards
Nernst potential
membrane potential at which there is 0 net driving force; value of membrane potential that balances an ion’s concentration gradient exactly
driving force = (membrane potential) - (Nernst potential)
when Nernst is far from membrane potential, there is a large driving force
Southern blot
DNA
gel electrophoresis
Northern blot
RNA (gene expression)
gel electrophoresis
Western blot
presence of proteins (antibodies radiolabeled)
gel electrophoresis; more specific than ELISA, but only qualitative
ELISA (enzyme-linked immunosorbent assay)
proteins (presence and concentration)
less specific than Western blot, but quantitative
mass spectrometry
used to identify protein/post-translational modifications
PCR (polymerase chain reaction), qPCR/RT-PCR
PCR: amplification of chromosome segments (small DNA seq)
qPCR/RT-PCR: quantifying SNPs for mRNA or DNA
Traditional Sanger Sequencing
uses PCR + ddNTPs to sequence genome
can be used for single gene/syndrome sequencing (small differential)
next-generation sequencing
DNA + beads, looks at pH difference
can be used for:
- single gene/syndrome sequencing (small differential)
- phenotype specific panel testing
whole exome/genome sequencing (WES/WGS)
best used if there is no high clinical suspicion of a recognized genetic disorder
can also be used as a last resort for sequencing point/small mutations
karyotyping
to check for aneuploidies
FISH (fluoresence in situ hybridization)
specific DNA sequence bound with fluorescent probes
to be used when there is a chromosomal abnormality and the specific DNA seq of mutation is known
chromosomal microarray
microchip-based testing
method for detecting copy number changes (gains or losses) across the entire genome; used when there is no high clinical suspicion of disorder
site specific testing
tests for known mutation in the family
CRISPR/Cas 9
used to add/delete genes in DNA sequences
RNAi (RNA interference)
DICER cleaves, RISC destroys identical RNA strands (hairpin loop)
Cre-Lox system
used to induce recombination between specific DNA sites (e.g., to study the effect of gene insertions or deletions)
prenatal diagnostic test: preimplantation
preimplantation genetic diagnosis (PGD): blastocyst bopsy (IVF technique)
tests if a specific genetic change is present in an embryo
prenatal screening & diagnostic tests: first trimester
screening:
- first trimester screen: ultrasound + maternal serum, screens for trisomy 21 & 18
- non-invasive prenatal screening (NIPT) AKA cell-free DNA (cfDNA) testing: maternal serum, screening for trisomies 21, 18, 13
diagnostic:
- chorionic villus sampling (CVS): boipsy of tissue from chorion
prenatal screening & diagnostic tests: second trimester
screening:
- quad or triple screen AKA maternal serum alpha-fetoprotein (MSAFP): maternal serum, screens for trisomies 21 & 18, neural tube defects (NTD)
- anatomy ultrasound: anatomical alterations and NTDs
diagnostic:
- amniocentesis: amniotic fluid (needle), cells of fetal origin
- percutaneous umbilical blood sampling AKA cordocentesis: umbilical cord sample of fetal blood
