Genetics Flashcards
What is haploinsufficiency?
When a protein truncating mutation lead to reduced production of the protein. Can still be functional
What is Dominant negative?
Missense mutation leads to production of abnormal protein that does not perform its usual function
What is a gain of function protein?
Missense mutation that produces a protein with increased activity or toxic effect, eg huntingtons
What is pleiotropy?
Multiple phenotypic expressions or disorders caused by a single gene. E.g. Marfan syndrome causing aortic root weakening, skeletal stretching and lens dislocation.
What is heteroplasmy?
The presence of a mixture of more than one type of mitochondrial DNA within a cell or individual. Usually need a threshold of mutation to lead to disease. It is a factor for the severity of mitochondrial diseases.
What is locus heterogeneity?
Variations in completely unrelated gene loci cause a single disorder
What is allelic heterogeneity?
Different mutations within a single gene locus (forming multiple alleles of that gene) cause the same phenotypic expression.
Eg One gene CFTR
- Multiple mutations All result in CF
What is genomic imprinting?
the epigenetic marking of a gene based on its parental origin
that results in monoallelic expression
What is uniparental disomy?
When both copies of a chromosome pair are derived from the same parent. One cause of abnormal imprinting patterns.
Can you detect balance chromosome translocations on chromosome microarray?
No
What does C-RET mutation cause?
MEN-2 adrenal phaeo, thyroid medullary cancers
What does SDH-B cause?
Exrta-adrenal phaeo with normal metanephrines
What does Karyotype detect?
Chromosome deletion/translocation/inversion
What does FISH detect?
Small section deletions/duplications
What does Microarray detect?
Specific DNA sequences checked against a chip, copy number variants, copy eutral changes, uniparental disomy
What does Sanger sequencing detect?
Testing for one gene variant - e.g CFTR
What gebe mutation causes Mody3?
HNF1a on chr 12
What causes MODY1?
HNF4a mutation
What causes mody2?
Glucokinase mutation
What does FBN1 Mutation cause?
Marfans
KCNQ1 causes?
Loss of function mutation -
LQT1
Slow potassium channels
What causes LQT2?
KNCH2 loss of function mutation
What causes LQT3?
SCN5A gain of function mutation
Sodium channel
What causes brugada syndrome?
SCN5A loss of function mutation
