Sickle Cell Anemia

1. Sickle Cell
Anemia
Sample Project
Biology – Mr. Woolf
Image source: 9

2. What is sickle cell?
• Sickle cell disease (SCD) affects the
production of red blood cells in the
body. Hemoglobin, the protein in blood
cells that carries oxygen, is not produced
correctly. This gives affected blood cells
a sickle, or crescent, shape. These blood
cells tend to be stiff and sticky, and they
can block blood vessels in limbs and
organs. This can cause pain, organ
damage, and increased risk of
infections.13 The structure of hemoglobin 15

3. What is sickle cell?
• Sickle cell anemia is one common form
of sickle cell disease. Anemia is a
condition in which the body does not
have enough red blood cells. Sickle cell
anemia occurs because sickle cells die
more quickly than normal blood cells,
and the body’s bone marrow cannot
replace the blood cells quickly enough.13
• Sickle cell anemia can lead to many
complications, including stroke, high
blood pressure, blindness, skin ulcers,
gallstones, and a life-threatening
condition called acute chest syndrome. 8
Image source: 13

4. How common is sickle cell?
• Sickle cell is most common among populations with ancestry in
sub-Saharan Africa; Spanish-speaking regions in the Western
Hemisphere (South America, the Caribbean, and Central America);
Saudi Arabia; India; and Mediterranean countries such as Turkey,
Greece, and Italy. The CDC estimates that in the U.S.:
• SCD affects 90,000 to 100,000 Americans.
• SCD occurs among about 1 out of every 500 Black or African-American
births.
• SCD occurs among about 1 out of every 36,000 Hispanic-American
births.
• About 1 in 12 African Americans carries the gene for the sickle cell
trait. 2

5. What causes sickle cell?
• Sickle cell is caused by a mutation in the hemoglobin,
beta gene, referred to as the HBB gene. This gene is
located on the short arm of Chromosome 11, and it
controls the production of the protein hemoglobin.
• The HBB gene contains 1,605 nucleotide base pairs, and
the hemoglobin gene is a sequence of 535 amino acids.
• A change in one nucleotide causes
a single amino acid in the protein to
change: glutamic acid is replaced
with lysine. This causes the sickle
cell trait.5

6. What causes sickle cell?
• The sickle cell gene is considered an autosomal recessive
trait. A person must inherit the sickle cell gene from both
parents in order to exhibit the disease.
• If a person only inherits s copy of the gene from one
parent, that person is considered a carrier – this person
would be said to have the sickle cell trait (SCT), but not
sickle cell disease (SCD). Carriers do not exhibit
symptoms of the disease.16
Image source: 10

7. What causes sickle cell?
Image source: 11

8. Diagnosing sickle cell
• Sickle cell disease and the presence of the sickle cell trait can
be diagnosed with blood tests or genetic tests.
• Sickle cell can be diagnosed at any age, but testing of
newborns is preferred, so that treatment can start as early as
possible.
• The disease can be diagnosed before birth by testing amniotic
fluid or placental tissue.
• Parents can be tested for the trait using the same blood tests in
order to determine if they are carriers.
(http://www.chop.edu/service/hematology/our-programs/
sickle-cell-center/diagnosing-and-treating-sickle-cell-
disease.html#when_best)

9. Treatment of sickle cell
• In the past, people with sickle cell disease often died
between ages 20 and 40. With treatment, people now live
to the age of 50 and beyond.16
• A bone marrow transplant (a.k.a, stem cell translpant) can
potentially cure children will sickle cell with success rates
of approximately 85% . However, a donor must be
available, and the transplant procedure is risky, resulting
fatality in 5-10% of cases. Therefore, it is typically only
used in severe cases.6
Image source: 7

10. Treatment of sickle cell
• Ongoing treatments for the symptoms of SCD include
drugs (pain relievers, antibiotics, hydroxyuria), blood
transfusions to reduce stroke risks, vaccines to reduce
infection risk, and supplemental oxygen.
• During 2005, medical expenditures for children with
SCD averaged $11,702 for children with Medicaid
coverage and $14,772 for children with employer-sponsored
insurance. About 40% of both groups had at
least one hospital stay. 2

11. Interesting fact…
• People who carry the sickle cell trait are resistant to
malaria, a deadly insect-born disease. Many researchers
believe that this survival advantage accounts for high
rates of the sickle cell trait in populations that descend
from areas where malaria was historically common.10

12. Global malaria vectors
Image source: 4

13. Families and sickle cell
Tiffany Dews, 33
Richmond, Va.
“When I first got pregnant, my intention was not to be a stay-at-home mom.
My intention was to work and finish school, but of course, plans change.
Both my husband and I have the trait for sickle cell disease, and combined
we have two children, Tracy and Riley, with the disease. There’s a one in
four chance each time we decide to have kids that we would pass on the
disease.
Years ago, [children with sickle cell disease] were not making it past the age
of 20 or 21. So my hope is that they will have kids, and hopefully not have
kids with the disease.” 1

14. Families and sickle cell
• For a family with insurance, typical medical costs for a family
member with sickle cell disease range from $10,000-15,000 per
year.2
• Parents of children with sickle cell disease need to educate
themselves about symptoms and complications of the disease, and
must monitor their child carefully. Children with the disease will
require frequent doctor’s visits.12
• Patients and family members often benefit from support groups,
where they can share information and coping strategies.12
• A person with a family history of sickle cell may want to be tested for
the trait, and may consider this information when making
reproductive and family planning decisions.12

15. References
1. Barrow, K. (2011, March 07). Pain, persistence, family: Sickle cell disease. Retrieved April 15, 2014, from
http://www.nytimes.com/2011/03/08/health/views/08sickle.html?_r=0
2. Center for Disease Control and Prevention. (n.d.). Sickle cell data and statistics. Retrieved April 15, 2014,
from http://www.cdc.gov/ncbddd/sicklecell/data.html
3. Children's Hosoital of Philadelphia. (n.d.). Overview of sickle cell disease. Retrieved April 15, 2014, from
http://www.chop.edu/service/hematology/our-programs/sickle-cell-center/diagnosing-and-treating-sickle-
cell-disease.html#when_best
4. Despommier, D., Racaniello, V., & White, J. (2004). Malaria. Retrieved October 20, 2014, from
http://www.medicalecology.org/diseases/malaria/malaria.htm.
5. Genetics Home Reference staff, National Institutes of Health. (2009). HBB. Retrieved April 15, 2014,
from http://ghr.nlm.nih.gov/gene/HBB
6. Healthwise staff. (2014, March 12). Stem cell transplant for sickle cell disease. Retrieved April 15, 2014,
from http://www.webmd.com/cancer/bone-marrow-transplant-for-sickle-cell-disease
7. Leukemia: Improving efficiency of bone marrow transplants. (n.d.). Retrieved April 15, 2014, from
http://fbresearch.org/leukemia-improving-efficiency-of-bone-marrow-transplants/
8. Mayo Clinic. (n.d.). Sickle cell anemia - complications. Retrieved April 15, 2014, from
http://www.mayoclinic.org/diseases-conditions/sickle-cell-anemia/basics/complications/con-
20019348
9. NHS England. (2014, May 21). Sickle cell anaemia: Causes. Retrieved April 15, 2014, from
http://www.nhs.uk/Conditions/Sickle-cell-anaemia/Pages/Causes.aspx

16. References (cont.)
10. Mutations and malaria: Pauling's adventure in genetics. (2009, January 13). Retrieved April 15, 2014, from
http://paulingblog.wordpress.com/2009/01/13/mutations-and-malaria-paulings-adventure-in-genetics
11. Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition.
(2003). Retrieved April 15, 2014, from http://medical-dictionary.
thefreedictionary.com/sickle%2Bcell%2Bdisease
12. National Institutes of Health. (2012, September 28). Living with sickle cell anemia. Retrieved April 15,
2014, from http://www.nhlbi.nih.gov/health/health-topics/topics/sca/livingwith.html
13. National Institutes of Health. (2012, September 28). What is sickle cell anemia? Retrieved April 15, 2014,
from http://www.nhlbi.nih.gov/health/health-topics/topics/sca
14. Oregon State University Libraries Special Collections & Research Center. (2009, January 13). Mutations
and malaria: Pauling's adventure in genetics. Retrieved April 15, 2014, from
http://paulingblog.wordpress.com/2009/01/13/mutations-and-malaria-paulings-adventure-in-genetics
15. Reproduced pastel drawing of the hemoglobin structure. (n.d.). Retrieved April 15, 2014, from
http://scarc.library.oregonstate.edu/coll/pauling/blood/pictures/1964b4.1-hbmodel.html
16. U.S. National Libraries of Medicine, National Institutes of Health. (2014, February 24). Sickle cell
anemia. Retrieved April 15, 2014, from
http://www.nlm.nih.gov/medlineplus/ency/article/000527.htm