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18 Cards in this Set

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What is anemia?
A pathological deficiency in the oxygen-carrying component of the blood, measured in unit volume concentrations of hemoglobin, red blood cell volume, or red blood cell number.
Lab Values of Hemoglobin Male vs. Female
Hematogrit Lab Values Male vs. Female
Hematocrit(Hct)
What is the Mean Corpuscular Volme (MCV)
Mean corpuscular volume (MCV)
86 –98 μm3/cell
Basics of Sickle Cell Anemia
Sickle cell anemia is inherited form of anemia

-Red blood cells (RBC) become rigid and sticky and are shaped like sickles or crescent moons

-These irregular-shaped RBC die prematurely

-Results in chronic shortage of RBC

-They also get stuck in blood vessels and slow or block blood flow and oxygen = pain + complications

-No cure for most people
Sickle Cell Trait versus Sickle Cell Disease
Sickle cell trait

-Have one gene for the disease
-No signs and symptoms
-Don’t develop the disease unless exposed to low oxygen
-Approximately 1 in 12 black Americans
________________________

Sickle cell disease

-Have two genes for the disease
-Show signs and symptoms after 4 months of age
-Some people have mild symptoms
-Others have severe symptoms and need frequent hospitalization.
Signs & Symptoms of SCA
-Anemia –sickle cells very fragile

-Pain episodes (crises)
–sickle-shaped RBC block blood flow through tiny blood vessels

-Hand-foot syndrome –swollen hands and feet often first sign of disorder in babies

-Jaundice –liver overwhelmed by rapid breakdown of RBC

-Frequent infections –sickle cells can damage spleen

-Stunted growth –due to lack of oxygen and nutrients needed for growth

-Vision problems
What causes SCA
Mutation in gene responsible for making hemoglobin
What is the disease etiology?
Autosomalrecessive disorder of Hgb

-Missensemutation causes an amino acid substitution (valinefor glutamine)

-Prevalence variable among populations

-Mutation evolved to confer resistance to malaria and thereby provided a survival advantage to heterozygotes(Heterozygote Advantage)
Evolution of Defective Gene
Sickle cell anemia evolved many years ago in Africa, Mediterranean, Middle East, and India

-Malaria epidemics were rampant
-Some people developed a genetic mutation that caused RBC to change shape
-These sickle cells interfered with growth of parasite (Plasmodium) that causes malaria
-Sickle cell trait allowed some to survive malaria outbreaks
Novel Property Mutation
A change in the amino acid (glufor val) sequence confers a novel property on the protein (Hgb) that results in a disease (sickle cell anemia)
What is the pathogenesis of the disease?
The amino acid substitution (valfor glu) causes a decreased solubility of deoxygenated Hgb

-This Hgbpolymerizes, forming a gelatinous network that stiffens and deforms the cell
-These cells occlude capillaries causing infarctions and tissue injury distal to that site
-Normal RBCslive 90 to 120 days
-Sickle cells die after 10 to 20 days
-Chronic RBC shortage = anemia
What is the inheritance risk?
Future children of an affected person have a risk dependent upon the genotype of the other parent

-Future sibs of an affected patient have a 25% chance of HgbSdisease and 50% chance of HgbStrait
Inheritance Risk
In the United States
80,000 Americans have the disease
-1 in every 500 African American births
-1 in every 1000 Hispanic births
__________________________

Two million Americans have the trait
-1 in 12 African Americans
-50% chance of being a carrier
-25% chance of having the disease
Complications
-CVA (cerebral vascular accident) or stroke

-Acute chest syndrome
-Chest pain, fever, difficulty breathing
-Caused by lung infection or trapped sickle cells in lungs

-Antibiotics, blood transfusions, and bronchodilators

-Organ damage
-i.e., kidneys, liver, spleen
Other Complications
-Leg ulcers

-Gallstones due to high bilirubinfrom RBC breakdown

-Priapism
What is the treatment?
-Bone marrow transplant offers potential cure

-Few people have suitable donor

-Treatment usually aimed at avoiding crises
-Antibiotics –children take penicillin until 5 years
-Pain meds

-Hydroxyurea–appears to stimulate fetal Hgbthat helps to prevent sickle cell formation
-Long-term use may lead to leukemia or tumors

-Blood transfusions –increase normal RBC but can cause excess iron accumulation
-Supplemental oxygen
Experimental Treatments
-Gene therapy –correct defective gene and insert into bone marrow

-Butyric acid –may increase fetal Hgb

-Clotrimazole–prevents water loss from RBC which may reduce number of sickle cells

-Nitric oxide –helps dilate blood vessels and reduces stickiness of RBC; may also prevent formation of sickle cells