B1-3 How can and should genetic information be used? How can we use our knowledge of genes to prevent diseases?

Question 1

What two diseases are caused by faulty alleles of only a single gene?

Answer 1

Huntington’s disease and Cystic Fibrosis

Question 2

What type of allele causes HD?

Answer 2

Dominant - Hh or HH

Question 3

What type of allele causes CF?

Answer 3

Recessive - cc

Question 4

What happens if the person has only one copy of the recessive allele? e.g. Cc

Answer 4

This means they do not have the disorder, but they are a carrier and can pass it down to their children.

Question 5

Recall the symptoms of Huntingtons:

Answer 5

Loss of memory, clumsiness, speech difficulties, forgetfulness, mood changes, hard to focus and shaking

Question 6

Recall the symptoms of Cystic Fibrosis:

Answer 6

Breathing difficulties, thick/excessive mucus,chest infections, lack of nutrients, difficulty in digestion.

Question 7

Please use a Punnet Square to determine: a) The outcomes of all offspring from someone who has Huntingtons - Hh and someone who is normal. b) The outcomes of all offspring from two carriers of Cystic fibrosis.

Answer 7

a) 50% chance of no disorder, 50% chance of Huntingtons

b) 25% chance of nothing, 50% chance of carrier & 25% of having CF

Question 8

What are the uses of Genetic testing for adults, children and embryos?

Answer 8

• Testing embryos for embryo selection (PGD).
• Testing people or embryos for genetic diseases.
• Testing people to before prescribing drugs - to see whether or not they will be affected.

Question 9

What are the implications of this information being used by others?

Answer 9

Employers may think twice about promoting you as they may be investing in someone who will not be around.
Life Insurance would be more expensive as they have a higher risk to die earlier than others - people may have to lie to these companies, or even put off a genetic test in fear of losing insurance to help their families once they die.

Question 10

What is IVF?

Answer 10

IVF is In-vitro fertilisation - meaning that the egg is fertilised outside the mothers womb, then implanted again to develop. This is part of the PGD process.

Question 11

What are the two different genetic tests?

Answer 11

Amniocentesis and Chronic Villus Test

Question 12

What is the process of Amniocentesis?

Answer 12

1. Large needle is inserted into womb through stomach.
2. Syringe like motion extracts amniotic fluid.
3. Fluid is then tested.

Question 13

What is the process of Chronic Villus?`

Answer 13

1. A suction stick is inserted into the mothers vagina.
2. Suction is then used to remove some of the placenta.
3. The placenta contains amniotic fluid.
4. It is then tested.

Question 14

What are the similarities between the two tests?

Answer 14

1. Results aren’t 100% reliable
2. Both carry risks of miscarriage
3. Both carry ethical implications

Question 15

What are the differences between the two tests?

Answer 15

1. Almost no risk of infection with Chronic Villus whereas small risk with amniocentesis
2. Results at 10-12 weeks with Chronic Villus - slower with amniocentesis at 15-18 weeks

Question 16

The issues surrounding Genetic Testing

Answer 16

• Not 100% safe - could cause a miscarriage
• May not be 100% accurate - people might get false results. They make bad decisions based on this incorrect information.
• Should they even have children if they are positive?
• Should other family be alerted to be tested?
• Should the pregnancy be terminated?
• Is it fair to pressure them into their own choice?

Question 17

What is the process of Pre-Implantation Genetic Diagnosis?

Answer 17

1. Fertility drug is taken so mother can release several eggs.
2. Eggs collected into a Petri-dish
3. Eggs are fertilised - IVF
4. At the 8-cell stage, one cell is removed from each embryo and tested
5. Only healthy cells are inserted into the mother
6. The others are discarded

Question 18

What are the implications of PGD?

Answer 18

• This could lead to people choosing their babies, not based on medical conditions, but based on appearance. This is unethical as people should love their creation.
• It is a natural process, people should not interfere with it and ‘play god’.
• The embryo has the right to a life, and is seen as murder by many.