Lecture 5

1.
What is direct testing?
Looking at DNA or RNA of a gene
2.
What is cytogenetic testing?
Examining chromosomes
3.
What is biochemical testing?
Assaying certain metabolites
4.
What genetic services make up the team involved in genetic testing? (3)
"Clinicians, lab technicians, counselling"
5.
When is someone referred to a gentics clinic? (5)
"A child is born with severe abnormalities, family history of medical condition esp cancer esp if a member is diagnosed with cancer at a young age, pregnancies in women over 35, women prone to miscarriage, anyone uncertain of genetic risk"
6.
What is the difference between diagnostic testing and presymptomatic testing?
"Diagnostic testing is after symptoms have developed, presymptomatic testing is before symptoms and is predictive"
7.
What are some issues with genetic testing? (4)
"Genetic heterogeneity, non penetrance, expressivity, non paternity"
8.
What is locus heterogeneity?
Same clinical phenotype arises from different mutations at different loci
9.
What is allelic heterogeneity?
Different alleles within same gene produce similar phenotype
10.
What is an example of a disease for locus heterogeneity?
Retinitis pigmentosa
11.
What is an example of a disease of allelic heterogeneity?
Cystic fibrosis
12.
What is penetrance?
The proportion of people who express a phenotype of a genetic mutation (as opposed to those who have the mutation but are asymptomatic)
13.
14.
When can genetic testing take place? (3)
"Pre implantation (IVF), prenatal, presymptomatic"
15.
What fluid is tested in prenatal genetic testing?
Amniotic 
16.
What was prenatal testing initially performed as a test for?
Down syndrome (trisomy 21)
17.
What are other reasons for pre natal diagnosis? (4)
"Provide reassurance and reduce anxiety in high risk groups, to prepare those with an affected fetus, to enable treatment of affected foetuses, to allow parents of an affected fetus to make an informed choice"
18.
What are examples of non-invasive prenatal diagnosis for Down syndrome? (4)
"Reduction of AFP (maternal serum alpha-feto protein), high Inhibin A and human chorionic gonadotrophin (maternal serum screen), low oestriol (maternal serum screen), ultrasonography"
19.
What are invasive techniques for prenatal diagnoses? (2)
"Amniocentesis, Chorionic villus sampling"
20.
Which of the invasive techniques have a higher risk of fetal loss?
Chorionic villus sampling
21.
What is pre implantation genetic diagnosis?
Selection of embryos free from genetic conditions in IVF pregnancies