1. Inheriting a Genetic Disorder

2. What are genetic disorders?
A genetic disorder is an abnormal condition that a person inherits through their genes or chromosomes.

3. What are genetic disorders?
Some are caused by mutations in DNA.
For example, sickle cell disease which you learned about yesterday!

4. What are genetic disorders?
This is a picture of ALL your chromosomes called a “karyotype”.
Others are caused by bigger changes in the chromosome.
For example, having too many chromosomes – Down Syndrome.

5. Cystic Fibrosis
Let’s take a closer look at a genetic disorder called Cystic Fibrosis.
Watch this video to learn about this condition.

6. How do you get a genetic disorder?
Genetic disorders like Cystic Fibrosis are NOT contagious! You can’t catch them from someone else who is sick!
You inherit them from your parents.
How do you know which children are at risk for inheriting Cystic Fibrosis?

7. How do you get a genetic disorder?
Each person has 2 cards – a yellow card and a pink card.
These alleles represent a trait that can be inherited from a parent.
Each person here is heterozygous for the trait. They have 2 different alleles!
Let’s model how genetic disorders like Cystic Fibrosis can be inherited. N m

8. How do you get a genetic disorder?
You’ll do this simulation with a partner.
Hold the cards behind your back and shuffle them up.
On the count of three, both people should pull out one of the cards.
These cards represent the 2 genes a child inherited from the parents (GENOTYPE).

9. How do you get a genetic disorder?
Repeat 3 more times with your partner, so you have the genotypes of 4 children.
Both yellow cards…
Both pink cards…
1 pink & 1 yellow…
Genotype = mm
Genotype = Nm
Genotype = NN N m N m m N

10. Who is affected by Cystic Fibrosis?
“N” represents the normal gene.
“m” represents the mutated gene that causes cystic fibrosis – it’s recessive.
NN = both normal genes.
Nm = carrier of the mutated gene, but is unaffected by the disorder.
mm = both mutated genes, so this child has cystic fibrosis.

11. Who is affected by Cystic Fibrosis?
Let’s find out more about how Cystic Fibrosis is inherited.
Overall, the probability (% chance) of inheriting CF if BOTH parents are carriers is 25% (1 in 4).
But you may have had more or less than 1 child inherit the disorder.

12. How many offspring in our simulation inherited Cystic Fibrosis?
Normal Genes (NN)=
Unaffected Carriers (Nm) =
Cystic Fibrosis (mm)=
Total Babies =
% who inherited CF =

13. Can Cystic Fibrosis be cured?
People hope that gene therapy can one day provide a cure for genetic disorders like cystic fibrosis.
Gene Therapy - involves removing the mutated gene and replacing it with a healthy gene.
Watch this video to find out more…