Genetics Flashcards
define penetrance
likelihood of having a disease features if you have a gene mutation
define variant
any change in the DNA sequence, can be benign or pathogenic
define mutation
pathogenic variant
define polymorphism
variant that is prevalent in the general population
may have low penetrance effect on common disease
what is the common disease-common variant hypothesis (CDCVH)?
if a disease is common in a population (>1%) then specific variations in the genetic code will also be common in the populations
what type of inheritance does the CDCVH work for?
polygenic disorders
multiple genes involved
factors that increase the chance of a variant being pathogenic
frame shift premature stop codon highly conserved area introns remain in coding sequence exon mutated rather than intron splice site known disease-causing mutation
what to question when finding a causative variant?
is it in a coding bit of gene- exon?
does it affect the gene? (consider degenerative nature of DNA)
exclude those variants known as polymorphisms
is it in a gene that causes disease?
does the pattern of inheritance match- FH?
classifying a variant
Class 1= definitely benign Class 2= probably benign (>90%) Class 3= variant of uncertain significance Class 4= probably pathogenic (>90%) Class 5= definitely pathogenic
what does NGS sequence?
the whole genome
what process should be done to NGS once the whole genome has been sequenced?
filtered to look at the part of the genome related to a specific disease
what is the exome?
sequencing the coding part of the DNA sequence
why is sequencing the exome better than the whole genome?
cheaper
less time-consuming
may find several diseases if sequence the whole genome (impossible to consent for)
what genetic test do you use to look at a specific gene?
PCR
what genetic test do you use to sequence several different genes/ parts of the exome?
NGS
