Gene Function to Clinic Flashcards
What proportion of breast cancers are associated with BRCA mutations?
5-10% all breast cancers.
-16% of breast cancer in
What proportion of breast cancers are associated with BRCA mutations?
5-10% all breast cancers.
-16% of breast cancer in
What chromosome is associated with early onset familiar breast cancer?
Chromosome 17q21.
What is the risk of developing breast cancer for women in the USA?
12%.
-85% with BRCA 1/2 mutation
What is the risk of developing ovarian cancer for women in the USA?
How does prophylactic surgery reduce breast and ovarian cancer risks?
Mastectomy - reduces risk by 90%.
Ovaries - reduces risk by 85%.
What is non-penetrance?
Genotype fails to manifest itself in phenotype because of modifying factors.
What are the main features of Treacher-Collins syndrome?
Abnormal development of bones / tissues in face.
- lack of migration of neural crest cells to face
- small chin, constricted airways, etc
What are the main prenatal tests, and when are they carried out? (3)
- Amniocentesis (~17w)
- Chorionic villus biopsy (~11w)
- Non-invasive testing (~10w)
What is pre-implantation testing (on cell from embryo) mainly used for?
- Monogenic disorders.
e. g. CF, beta-thalassaemia - Chromosome abnormalities
What is non-disclosure testing?
Parents do not wish to know if they are carriers, but wants children who do not have the genetic mutation.
-e.g. Huntington’s
What mutation is linked to obesity?
Leptin.
-hormone secreted by adipose cells to tell the brain to stop eating
What hormone opposes leptin?
Ghrelin.
-secreted when stomach is empty
What is gene therapy?
Introduction of functional DNA to replace mutated genes.
What is Leber’s congenital amaurosis (LCA)?
Inherited blindness (autosomal recessive). -gene therapy by subretinal injection improves vision
What gene is associated with Leber’s congenital amaurosis (LCA)?
RPE65 mutation.
What sort of mutation must be present in Leber’s congenital amaurosis (LCA) for gene therapy to be effective?
Missense mutation.
-single gene
What is pharmacogenetics?
The study of gene variation in relation to drug response.
-e.g. adverse effects
What enzyme in the liver is responsible for metabolic activation and elimination of most drugs?
Cytochrome P450 oxidases.
What specific cytochrome P450 oxidase metabolises 25% of drugs?
CYP2D6.
- e.g. rate limiting step for converting tamoxifen to endoxifen
- 6-10% caucasians don’t have it
What does personalised medicine involve?
Using genotype to tailor medical care.
-not used yet
What does homozygous APOE gene lead to?
Increased Alzheimer’s risk.
What chromosome is associated with early onset familiar breast cancer?
Chromosome 17q21.
What is the risk of developing breast cancer for women in the USA?
12%.
-85% with BRCA 1/2 mutation
