f Flashcards
(26 cards)
What’s nonconservative missense mutation and what’s an example?
biochemically different amino acid
sickle cell mutation of the B-globin chain of Hgb
CTC glutamic acid -> CAC valine
What is a nonsense mutation and what’s an example?
change an AA codon to a stop a stop codon
B-globin glutamine CAG -> UAG -> B-thalassemia
mendelian disorders
mutations in single genes that have large effects
IF someone is heterozygote for sickle cell anemia, what do their RBCs look like?
a portion of the Hgb is HbS and sickling occurs under specific circumstances like low O2: sickle cell trait
codominance and example
both of the alleys of a gene pair contribute to the phenotype
histocompatibility and blood group antigens
pleiotropism and example
single mutant gene that can lead to many end effects
sickle cell can also cause jams in small vessels like splenic fibrosis, organ infarcts, and bone changes
genetic heterogeneity definition and example
mutations at several genetic loci produce the same trait
childhood deafness- many autosomal recessive mutations
in autosomal dominant, children have what chance of getting it?
one chance in two
What is an example of variable expressivity?
neurofibromatosis type 1 can range from brown spots to skin tumors and skeletal deformities
dominant negative definition and example
mutant allel impairs function of the normal allele
OI
glucose-6-phosphate dehydrogenase deficiency is an example of what kind of transmission? clinical features?
x-linked recessive
predisposes red cell hemolysis in patients receiving certain drugs
What is an example of an x-linked dominant disorder? How is it transmitted?
vitamin D resistant rickets
affected mom: 1/2 sons and 1/2 daughters
affected dad: no sons and all daughters
good for analysis of large or multiple genes
gold standard for sequence determination
sanger sequencing
looks for particular sequence variants
may be used to analyze DNA obtained from cancer biopsies
pyrosequencing
identifies mutations at a specific nucleotide position
very sensitive
single-base primer extension
used for diagnosis of casual mutations that always occur invariant nucleotide positions
restriction fragment length analysis
look for mutations that affect length of DNA that can’t be easily detected by PCR
but won’t work if the trinucleotide repeat extension is too large (then use SB)
amplicon length analysis
used to monitor frequency of cancer cells or infectious load of certain viruses
can be used to detect somatic point mutations in oncogenes such as KRAS or BRAF
real-time PCR
herpes, HIV
can be performed on amniotic fluid, blood, cancer biopsies, archival tissue sections
looks for chromosomal abnormalities, subtle micro deletions, or translocations (HER2 or NMYC in neuroblastoma)
fluorescent in situ hybridization
can detect deletions and duplications of any size (too large for PCR and too small for FISH)
good for CFTR
multiplex ligation-dependent probe amplification (MLPA)
FISH requires prior knowledge to find genetic abnormalities, where as ____ does not
cytogenomic array technology
What is good for finding CNVs across the genome?
array-based comparative genomic hybridization (Array CGH)
routinely used when karyotype is normal but structural chromosomal abnormality is still suspected
uncovers mosaicism
SNP genotyping arrays
What are scattered throughout and so variable they’re good for differentiating between two individuals?
microsatellite
