Sickle Cell Anemia

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Sickle Cell Anemia

• A presentation by Sarah and Judy

http//www.thetech.org/genetics/images/ask/sickle_
cell_image_1.jpg
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What is Sickle Cell Anemia?

• An inherited blood disease
• Affects red blood cells
• A homozygous recessive genetic disorder, but may
  effect heterozygotes under extreme physical
  stress or under high altitudes

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An Inherited Trait
http//www.nhlbi.nih.gov/health/dci/Diseases/Sca/S
CA_Causes.html
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Sickle Cell Factoids

• In the United States, sickle cell anemia affects
  about 72,000 people. The families of most of the
  people affected come from Africa
• About 2 million Americans carry the sickle cell
  trait. About 1 in 12 African Americans have the
  trait

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Normal Histology

• Red blood cells are usually smooth edged and have
  a biconcave doughnut shape
• They last about 120 days in the blood stream
  before being taken out of circulation
• Hemoglobin, an oxygen-carrier protein, is found
  in red blood cells
• It is made up of 4 globin chains (2 alpha and 2
  beta)

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Red Blood Cells
www-medlib.med.utah.edu/ WebPath/jpeg5/HEME002.jpg

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Disease State, What Happens?

• Causes a sickling shape via a mutation in beta
  globin
• Hydrophobic patches are created on deoxygenated
  hemoglobin
• These patches stick to one another causing it to
  aggregate into chains
• Causing the observed sickle shape
• This abnormal shape impedes blood flow in small
  vessels
• Can cause pain, damage, and a low blood count
  (anemia)

http//www.mcg.edu/centers/sicklecell/images/2017.
jpg
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Sickle Cells
http//www.thedoctorwillseeyounow.com/articles/oth
er/sicklecell_3/sickle1a.gif
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Sickle Cells
http//www-medlib.med.utah.edu/WebPath/jpeg5/HEME0
15.jpg http//webanatomy.net/histology/blood/sickl
e_cells.jpg
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Possible Outcome

• Splenomegaly, enlargement of the spleen (if
  ruptured will cause severe internal bleeding)
• The spleen is an organ involved in the production
  and maintenance of red blood cells, the
  production of certain circulating white blood
  cells, and is a part of the lymph system and the
  immune system
• Because of its wide variety of functions, the
  spleen may be affected by many conditions
  involving the blood or lymph system
• Can be caused by sickle cells filling the red
  pulp and causing the spleen to expand

http//www.brown.edu/Courses/Digital_Path/Spleen/s
ickle_cell_anemia_2.JPG
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Other Possible Outcomes

• Infections
• Infants and young children are more susceptible
  to bacterial infections (ex meningitis)
• Pain Episodes
• Blockage of blood flow in joints, muscles, etc
• Can be mild to severe
• Stroke
• Occurs when blockage occurs in the brain

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Treatments

• General Treatment
• The goal of treatment is to relieve pain,
  prevent infections, and control complications if
  they occur
• Treatments include medications, blood
  transfusions, and specific treatments for
  complications
• Bone marrow transplant
• Will provide new normal stem cells
• Because all blood cells arise from stem cells,
  providing the person with normal stem cells will
  assist in their production of normal red blood
  cells

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Benefit?

• Being a carrier for this disease is beneficial in
  some parts of the world
• Where malaria is prevalent, being a carrier
  creates a resistance to the deadly disease
• Individuals who are heterozygous for the sickle
  cell trait (carriers) are selected for in this
  environment
• When a heterozygous individuals RBC becomes
  infected with the malaria parasite, the cell
  sickles and will be caught and destroyed in the
  spleen

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Concluding Remarks

• An inherited trait, not infectious
• Sickle caused by abnormal heme group
• Treatment possible, research for cure ongoing
• Homozygous individuals are unfit, heterozygous
  individuals have advantage only in environments
  with malaria risk

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Video
Video 2 Sickle Cell Mouse (Non-Transplanted)
http//www.mssm.edu/labs/frenette/sickle_pnas.shtm
l
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References

• Ross, et al. Histology A Text and Atlas 4th ed.
  2003, Ch 9.
• http//www.nlm.nih.gov/medlineplus/sicklecellanemi
  a.html Nov. 21, 2005
• http//www.nhlbi.nih.gov/health/dci/Diseases/Sca/S
  CA_WhatIs.html Nov. 21, 2005
• http//www.sicklecelldisease.org/about_scd/faqs.ph
  tml Nov. 21, 2005
• http//www.sicklecelldisease.org/ Nov. 21, 2005