Flashcards in gene function Deck (42)
what comprises hypothesis generating?
without any prior knowledge we can identify which genes, proteins and pathways are involved in development and disease whether they are monnogenic or complex. Identification of genes allows for accurate diagnosis, counselling and determination of function and also identifies a target for therapy
how is genetics used?
for diagnosis, counselling, therapy treatment and prevention
what diagnosis can there be for neonates?
presymptomatic, preimplantation or prenatal
what genes may involve counselling?
BRCA1/2 for ovarian and brast cancer development
what is BRCA mutations responsible for?
responsible for 16% of familial cancers and 5-10% of all breast cancers
what is the increase of risk for breast and ovarian cancer with BRCA1/2 gene?
usual breast risk is 12% by 90y/o
with BRCA mutations increases risk to 85% by 70y/o
usual ovarian risk is <2%
with BRCA1 is 55% and BRCA2 25%
what are the benefits of being tested for BRCA?
mind at rest
risk reducing activities such as diet and tamoxifen
other family members
why does testing direct treatment plan?
BRCA mutations in cancer respond to other treatments better than usual treatments - cisplatin and PARP inhibitors
what are the disadvantages of testing for BRCA?
false reassurance of never getting breast cancer
complications e.g. insurance
what are the prophylactic options for BRCA?
removal of ovaries after having a family - reduces risk by 85%
preventative masectomy - reduces risk by 90%
these are popular due to advances in reconstructive surgery
what can you presymptomatically test for?
late onset disorders - breast and colon cancer, HDD and retinitits pigmentosa
why would diagnostics help counselling?
confirm the clinical diagnosis, identify carriers of recessive mutations and identify cases of non-penetrance
what is TCS?
it is a congenital abnormality where there is deformity of ears, eyes, cheekbones and chin and can range from mild to severe
how would TCS be tested for?
amniocentesis - 17 weeks
CVS - 11 weeks
NIPD - 10 weeks
what else can be tested for in prenatal diagnosis ?
triploidy and single gene disorders
what is NIPD?
non invasive prenatal diagnosis - it is a new non invasive method that is based on NGS of the mothers blood at ten weeks - cell free DNA screening
what is the process of NIPD?
the maternal serum contains placental DNA that matches the foetal genome. NGS genome sequencing is performed on the cell free DMA and the results will identify trisomies
what are the advantages of NIPD?
much more accurate (<99% compared to current 85% for Downs) and much lower false positive rate (0.06% compared to current 5.4% for Downs)
what is pre-implantation diagnosis?
it is when there is HLA typing to match the cord blood stem cells for siblings for a saviour sibling
who oversee pre-implantation diagnosis?
HFEA - human fertilisation and embryology authority
when can pre-implantation non disclosure testing be performed?
for HDD - without knowledge of the disease status of the parent
what is gene therapy?
it is the use of genetic material such as DNA or RNA as a medicine q
what is classic gene therapy?
it is the introduction of functional genes in the form of DNA to replace mutated genes
what is novel gene therapy?
it is using gene technology to repair mutated genes, silence overactive genes or provide immune cells with the tools that they need to recognise and kill cancer cells and infections
what is Leber's congenital amaurosis?
LCA is a rare inherited eye disorder that has over 22 genes implicated and is a recessive inheritance pattern. It account for 10-18% of congenital blindness, and results in blindness at birth or in infancy, or impaired visual function resulting in inability to see wise with only a small circle of vision. It is a target of gene therapy
why is the eye a target for gene therapy?
it is immune privileged and is accessible for subretinal injections
what is an example of gene therapy in LCA?
RPE65 mutations have been identified in LCA families which is a retinal enzyme. A sub-retinal injections between RPE and photoreceptors that is made of adeno associated virus containing RPE65 and RPE65 promoter may restore vision - unsure of benefits as of yet
what is DNA editing?
CRISPR/Cas9 is a find and replace process. A cell is transfected with an enzyme complex containing a guide molecule to find the target DNA strand, healthy DNA copy and a DNA cutting enzyme. The enzyme cuts off the defective DNA strand and it is replace with a healthy copy
what does pharmacogenetics show?
there is a correlation between the effect of drugs and the genetic constitution of patients