Lecture 3

Question 1

What are the three types of genetic testing?

Answer 1

Direct testing, Cytogenic testing, Biochemical testing

Question 2

What is direct testing?

Answer 2

Looking at the DNA or RNA that makes up a gene

Question 3

What is a Cytogenetic test?

Answer 3

When the chromosomes are examined

Question 4

What is biochemical testing?

Answer 4

When you assay for particular metabolites

Question 5

What are the two uses of genetic testing?

Answer 5

Diagnostic and Predictive

Question 6

What is the purpose of predictive testing?

Answer 6

So that potentially life style changes can be made in order to improve the health outcome

Question 7

What are the two forms of genetic heterogeneity?

Answer 7

Locus Heterogeneity and Allelic heterogeneity

Question 8

What is locus heterogeneity?

Answer 8

When multiple mutations can cause the same phenotype from different loci

Question 9

What is allelic heterogeneity?

Answer 9

many mutations within the same gene can result in different phenotypes

Question 10

What is the concept of penetrance?

Answer 10

How likely it is that the gene will result in a phenotype as it can vary dramaticallly between individuals

Question 11

What is expressivity?

Answer 11

The idea that a gene will manifest itself in different ways between individuals even if the gene is identical

Question 12

What is the process of Prenatal Diagnosis?

Answer 12

when chromosomal and genetic analysis is achieved through either culturing cells from amniotic fluid or through analyisis of homrones or proteins in the mothers blood etc

Question 13

What are the non-invasive prenatal diagnostic methods?

Answer 13

Maternal Serum alpha-fetoprotein,
Maternal serum screen,
Ultrasonography

Question 14

What does Maternal Serum alpha-fetoprotein test for?

Answer 14

Tests for levels of AFP which are elevated in neural tube defects and reduced in downs syndrome

Question 15

What does the maternal serum screen test for?

Answer 15

AFP to detect neural tube defects/downs syndrome
High levels of hCG and inhibin A are seen in downs syndrome
Oestriol is low in downs syndrome

Question 16

What are the two methods of invasive prenatal diagnosis?

Answer 16

Amniocentesis

Chorionic Villus Sampling

Question 17

How does the test of amniocentesis work?

Answer 17

A small amount of amniotic fluid is collected for studies

Question 18

How does Chorionic Villus Sampling work?

Answer 18

Biopsy is performed on the villus area of the chorion either transabdominally or transcervically

Question 19

What is the advantage of chorionic villus sampling as opposed to amniocentesis?

Answer 19

Results can be obtained at an earlier date

Question 20

What is pre implantation diagnosis?

Answer 20

Several embryos are cultured and then are tested through FISH and other genetic techniques and only those found without mutations will be implanted

Question 21

What are the two key things required to prove that a gene is linked to a disease?

Answer 21

Mutation screening and Functional proof

Question 22

What is mutation screening?

Answer 22

Failure to notice the gene in a large sample of controls

The gene can be observed with a clear and relevant inheritance pattern in a pedigree chart

Question 23

What is functional proof with regards to linking a gene to a disease?

Answer 23

There must be proof thorugh things such as computer modelling that the change the mutation has on the final product is important or relevant with regards to the original proteins function

Question 24

What is the only currently avaliable treatment for those with genetic diseases?

Answer 24

Primary prevention where changes in lifestyle or potentially some drug treatments may prevent onset of the disease