1. 3 parents Student sheets Sheet no. Title Notes SS1 All about LHON
Reusable, one per pair
SS2
The 3 parent technique
SS3
Advice sheet
Consumable, one per student (optional)
SS4
A game of issues
Reusable, one per group
SS5
The issues
Reusable, one per group. Laminate and cut into cards.

2. All about LHON SS1 What is LHON? What causes it? A cell
chromosome
Section of DNA (a gene)
nucleus
What is LHON?
LHON is an eye disease that causes blindness. Unfortunately there are no treatments.
What causes it?
Inside the nucleus of all cells are chromosomes made of DNA. Sections of DNA called genes code for characteristics.
It happens because the mitochondria are not working properly. Mitochondria are the parts of the cell that produce energy.
Mitochondria
Cytoplasm
Nucleus
A cell
The mitochondria also contain a few genes. These only code for parts of the mitochondria.
Sometimes, there are mistakes in the genes of the mitochondria. If this happens the mitochondria don’t work properly. This is what happens in LHON.
How is it inherited?
People who have LHON have inherited it from their mother. During fertilisation she passes on her unhealthy mitochondria.
Child with LHON
Unhealthy mitochondria
Unhealthy mitochondria
Sperm
Egg
Fertilisation: the nucleus from the egg and sperm join.
A single cell is formed. This will divide many times to form an embryo.

3. SS2
3 parent technology
1. Get a donated egg from a healthy woman. Remove its nucleus and discard it.
Pipette
5. Wait for the egg to develop into an embryo.
Healthy mitochondria
Healthy mitochondria
6. Put it into the woman’s womb where it should develop into a healthy baby.
Egg cell from healthy woman
4. Put it in the healthy egg cell.
Woman has mitochondrial disease
Unhealthy mitochondria
2. Fertilise the woman’s egg with the man’s sperm in a glass dish.
Couple who want a baby
Nucleus with a mixture of the couple’s genes
Unhealthy mitochondria
Egg
Sperm
The embryo inherits everything from the parents except for the damaged mitochondria. The embryo inherits mitochondria from the healthy woman. So the baby ends up with one dad ...and two mums!
3. Take the nucleus out of their fertilised egg.

4. Advice sheet What is LHON?
SS3
Advice sheet
What is LHON?
LHON is a disease that affects the in the cells.
It is caused by a mistake in the
It is passed from mother to baby because...
Can the 3 parent technique help Maya and Jake?
If they use this technique the baby will have a mixture of genes from Maya and Jake and inherit their characteristics because...
But the baby will not have mitochondria from Maya because....
This is good because....
I think that the technique will / will not be able to help them because...

5. A game of issues SS4 Issue affects For the treatment
Against the treatment
In groups of 4 share out the cards. You will also need 16 counters.
The first player reads out an issue and says where they think it goes in the grid.
The other players each say ‘I agree’ or ‘I disagree’. If most agree, you win a counter.
If they all disagree, try to decide where the card should go.
When all the cards have been placed, the player with the most counters is the winner.
The couple
Their future child
Society as a whole

6. SS5
The issues 1 2 3 4
The mother needs to have a medical procedure to extract her eggs. This is a health risk.
It changes the genes of future generations so has unknown consequences.
It is very expensive to care for seriously ill people.
A life which is disease free is a happier one. 5 6 7 8
Caring for a child with a serious disease is a terrible thing to experience. Parents would do anything to avoid this.
Rather than wasting time and money on this, we should research solutions to other, more common health problems.
In some countries women are paid for donating eggs. They may be pressured to do this, and go through pain and health risks.
If we can stop children being born with serious illnesses then we should. It is a moral duty to help others. 9 10 11 12
There are other safer options available to the parents. This includes using donor eggs (eggs from another woman).
It allows the parents to have a healthy baby who shares genes with both of them. This is a right everyone should have.
This is a new procedure which has not been tested on humans. It could create children with health problems.
It is currently banned in over 40 countries – there must be a good reason why. 13 14 15 16
Mitochondrial diseases can cause serious health problems and can even result in death.
People are often worried about new techniques but this shouldn’t stop them being developed and used.
Interfering with genes in this way is ‘playing God’. No human has the right to do this.
It might not work. This would be very disappointing for the parents.