1. Sickle Cell Disease

2. What is Sickle Cell Disease?
Affects millions around the world, mostly in Africa
About 70,000 Americans are estimated to have the disease
About 1000 babies are born with the disease in the US each year

3. What is Sickle Cell Disease?
Sickle cell is passed on by a recessive gene
People with only one copy of the gene are healthy
Since they can still pass on the recessive sickle-cell gene, these people are called “carriers”
Sickle cell gene in blue…
Can be covered up by the dominant gene (red).

4. What is Sickle Cell Disease?
People with two copies of the sickle cell gene have sickle cell disease
If two people who are both carriers have children, what is the possibility of their child having sickle cell disease?
Set up a Punnett square to figure this out! (H is the healthy gene, h is the sickle cell gene) +
= sickle cell disease

5. Punnett Square H h H h HH Hh Hh hh
“Carriers” are heterozygous (they have one dominant gene and one recessive gene)
H h
There is a 25% chance that their child will have the sickle cell disease. H h HH Hh Hh hh

6. What does it do to you?
People with two copies of the sickle cell gene have sickle cell disease
The gene codes for hemoglobin, an important protein in red blood cells
The abnormal form of hemoglobin clumps together, which changes the shape of the red blood cells +
= sickle cell disease

7. What does it do to you? Sickled cells are fragile, sticky, and stiff
These cells can get trapped in blood vessels, making it impossible for blood to get through
Muscles and organs that depend on blood for oxygen and nutrients can suffer or even stop working

8. Why is it still around?
If sickle cell disease is so bad, why does the trait still exist in such high numbers?
Watch this video.(8 min)