__________________________

Genetic screening: to identify those with an increased risk of inheriting a disorder

• Often tied to ethnic background• May involve karyotyping or biochemical tests• Then treatment or counselling can be given• Huntington’s disease can be screened for (autosomal

dominant trait)

_____________________________

Risk groups:

• Pregnant women over 35 years old

• Parents with genetic abnormality in previous children

• Parents who have family members with genetic abnormalities

• Couple from high risk backgrounds for a specific disease

___________________________:

involves checking the fetus for a problem

• One of the processes is called amniocentesis

• during 16 week of pregnancy by inserting needle

• Uses amniotic fluid, which contains fetus cells

• An ultrasound can be used to prevent injury to mother or fetus

•to visually identify physical abnormalities

_________________________: is the result of foreign DNA inserted into an organisms DNA

Dr. Barbara _____________________ (1902-1992)

Research focused on making the connection between the behaviour of chromosomes in a special type of crossing over and the phenotypic effects on corn kernals

• 1951 - “Jumping gene” theory, now known as transposons

• Little attention was paid to her theories

• Transposons have large role in gene regulation and help explain wide range of variation in certain proteins (pigments)

• Received a Nobel Prize for her work in 1983 (over 30 years later)

____________________________:

direct use of genetic techniques to treat a genetic condition

Two methods:

1. Normal gene product can be given to an affected individual

• Used extensively today, example is insulin.

2. Manipulate the abnormal DNA in parent or offspring in order to better the disease

____________________: Physical alteration of genes.

•Can be used to correct some hereditary defects

• Involve inserting a proper working gene into the cell that lack the ability to produce their own protein

• Insulin, inserting that gene into pancreatic cells

• Need to use a vector to insert the gene, like a virus, which is site specific to pancreatic cells

• Once there the virus would insert the genes, giving these cells the ability to produce their own insulin

_____________________

• Transfer of technology to the private sector• Interesting facts:

– 50% of HG is non-coding “junk” DNA

– 30 000 – 35 000 genes

– gene transfer from bacteria

– Mutations 50% more likely in vs – 50% of HG is similar (transposable elements)

– 3 164 700 million nucleotides

– Crossing over more frequent in short chromosomes

_________________

• Clones have identical DNA to “parent”

• Dolly the Sheep (1997) by Ian Wilmut

• First mammal cloned from the nucleus of another adult mammal

___________________

• A technology that has replaced blood typing for paternity or criminal prosecutions

• Each person has a unique DNA “fingerprint” that can be identified from a small sample of DNA

A) “Prospective parents who have a family history of a genetic condition that can be identified in prenatal testing and are at risk should be required to undergo genetic screening.”

b) “Ultimately you would hope all parents would take advantage of screening techniques in an effort to reduce the frequency of children born with genetic abnormalities.”

c) “As long as there are strict guidelines controlling gene therapy, society will not have to be concerned about abuses of this technology.”

d) “Private biotech companies that have invested millions of dollar in the Human Genome Project have a right to obtain patents for specific gene sequences. Other private companies or research facilities should have to ask permission or even pay to use this information in their studies.”

Can you give possible points in support of or opposition to the following statements?

PRACTICE QUESTIONS

1. Why is it advantageous to control breeding in plants and animals?

2. How is inbreeding performed in a) plants, b) animals?

3. List the problems that can result from inbreeding.

4. Briefly outline three of the roles of genetics in medicine.

5. What types of individuals are most likely to consult with a genetic counsellor?

6. Briefly explain how amniocentesis is performed.