yohan kim. first to described in 1904 by james b. herrick. ◦ found “elongated and...
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Sickle Cell Disease
Yohan Kim
First to described in 1904 by James B. Herrick. ◦ Found “elongated and sickle-shaped” red blood cells (RBCs) from
a patient suffering from anemia
A multisystem disease, associated with episodes of acute illness and progressive organ damage
Most common in African heredity population◦ Occurs in about 1 of every 500 births
Clinical management of sickle cell disease is still basic and no drugs have been developed that specifically tar-get the pathophysiology of this disease
Affects about 70,000 people in the US
Sickle Cell
Global distribution & Malaria
2 Types of Hemoglobin HbF(More O2), HbA(Less O2)◦ Newborn – 5:5~8:2, 6
months – 1:99
Sickled hemoglobin is caused by a mutation of the gene of HbA
In the amino acid sequence va-line takes the place of glutamic acid at the sixth position.
HbA become C-shaped or sick-led when the patient’s oxygen saturation is low.
Pathophysiology
Pathophysiology
Reduced flexibility impairs blood flow through vessels
Repeated de-oxygenation can damage the cells enough to make sickling permanent
short-lived (10 to 20 days instead of the normal 120 days)
Sickled RBC
No clear symptoms shown
Indications may be visible during growth
Newborns usually of normal length and weight at birth
Develop a gradually increasing deficit in height and weight as they age
After time of the normal adolescent growth spurt, they be-gin to catch up with their normal peers. ◦ (Girls 15 to 17, boys 18 to 19)
Delayed puberty also occurs.
Signs and symptoms
Treatment of sickle cell crisis is usually symptomatic
Referring the patient immediately
Referral
Based on analysis of hemoglobin
Protein electrophoresis or chromatography
Hemoglobin mass spectrometry and DNA analysis increasingly used ◦ Enable high-throughput testing.
Diagnostic test
HbSS - inherited two sickle cell genes (S); one from each par-ent. ◦ The most common type
HbSC - inherited a sickle cell gene (S) from one parent and a gene for abnormal hemoglobin (C) from the other ◦ 20% to 30% of cases, usually a milder form of sickle cell disease.◦
HbS beta thalassemia - one sickle cell gene from one parent and one gene for beta thalassemia from the other parent.
Other: HbSD, HbSE, and HbSO -inherited one sickle cell gene and one gene for an abnormal type of hemoglobin
HbAS - sickle cell trait
Differential diagnosis
Not a disease, generally regarded as an asymptomatic con-dition.
When compared to controls, is no difference
Some physiological differences during exercise or at high al-titudes
Following exercise -> increase in the number of sickled cells. ◦ exertional sickling
The presence of sickled cells after physical exertion is even greater at higher altitudes
Sickle cell trait
Explanations for sudden deaths due to sickle cell anemia are not entirely clear.
Data indicate an association between sickle cell trait and sudden death there is no direct evidence of cau-sation.
Dehydration, hyperthermia and acidosis associated with extreme physical exertion suggested
Results include rhabdomyolysis (muscle break-down), acute renal failure and coronary vasoconstriction
Sickle cell trait
Hydroxyurea (medication)
◦ Oral efficacy and low toxic effects
◦ Increase hemoglobin concentrations
◦ Decreasing platelet and white cell counts
◦ Changing expression of adhesion molecules
◦ Nitric oxide generation
Treatment
Red blood cell transfusion◦ Corrects anemia
◦ Decreases the percentage of sickled hemoglobin
◦ Suppresses sickle synthesis,
◦ Reduces polymerization.
◦ Necessary if the hemoglobin concentration is high, or if rapid decrease in sickled hemoglobin percent-age needed
Treatment
Hematopoietic stem cell transplantation
◦ AKA bone marrow
◦ The only cure for sickle cell disease
◦ First bone marrow transplantation for sickle cell in 1983 on 8-year-old patient with leukemia and sickle cell disease The bone marrow transplantation cured both dis-
eases
Treatment
Hematopoietic stem cell transplantation
◦ Indications1. Stroke or CNS event lasting longer than 24 hours2. Abnormal brain MRI3. Elevated transcranial Doppler4. Acute chest syndrome with recurrent hospital-
izations5. Two or more vaso-occlusive crises requiring hos-
pitalizations6. RBC alloimmunization
Treatment
Splenectomy
◦ The spleen is the organ most often affected by sickle cell disease.
◦ To prevent complication
◦ Also reduces patients’ need for transfusion
◦ Decreases splenic complications
◦ Further eliminates pain
Treatment
Acute pain - most common cause of hospital admission
Infection - major cause of morbidity and mortality
Stroke
Acute chest syndrome - second most common cause of hospital admis-sion
Pulmonary hypertension
Heart disease
Renal complications - almost inevitable, hemoglobin polymerize in the renal medulla, because of the low oxygen
Complications
About 90% of patients survive to age 20
Close to 50% survive beyond the fifth decade.
Prognosis
No methods to prevention sickle cell disease
Screening and diagnosing sickle cell in advance will help prevent complications in the future
Engaging and educating patients before complications begin are also good ways of preventing complications.
Prevention
A college football player with sickle cell trait (SCT) who col-lapsed minutes after running 16 successive sprints of 100 yards each at sea level.
The player, 19 year old, African American, was apparently healthy when running.
No exertional heat illness was present.
After collapsing, went into coma and developed fulminant rhab-domyolysis, profound lactic acidosis, acute myoglobinuric renal failure, refractory hyperkalemia, and disseminated intravascular coagulation.
Died about 15 hours after admission to hospital
Case study
Cause of death was acute exertional rhabdomyolysis as-sociated with SCT
appears that sickling can begin within 2-3 minutes of maximal exertion and can reach grave levels very soon
Being urged on by coaches can pose problem
Heat, dehydration, altitude, and asthma can increase the risk
Screening and simple precautions can prevent this unique syndrome and enable SCT athletes to thrive in their sports
Case study
1. Redding-Lallinger R, Knoll C. Sickle cell disease--pathophysiology and treatment. Current Problems In Pediatric And Adolescent Health Care. 2006;36(10):346–376.
2. Parrish M R, Morrison J C. Sickle cell crisis and pregnancy. Seminars in Perinatol-ogy. 2013;37(4):274–279. doi:10.1053/j.semperi.2013.04.006.
3. Rees DC, Williams TN, Gladwin MT. Sickle-cell disease. Lancet. 2010;376(9757):2018–2031. doi:10.1016/S0140-6736(10)61029-X.
4. Sheth S, Licursi M, Bhatia M. Sickle cell disease: time for a closer look at treat-ment options? British Journal Of Haematology. 2013;162(4):455–464. doi:10.1111/bjh.12413.
5. Apanah S, Rizzolo D. Sickle cell disease: Taking a multidisciplinary approach. JAAPA: Journal of the American Academy of Physician Assistants (Lippincott Williams & Wilkins). 2013;26(8):28–33. doi:10.1097/01JAA.0000432497.24151.d4.
6. Aloe A, Krishnamurti L, Kladny B. Testing of collegiate athletes for sickle cell trait: what we, as genetic counselors should know. Journal Of Genetic Counseling. 2011;20(4):337–340. doi:10.1007/s10897-011-9366-9.
7. Anzalone ML, Green VS, Buja M, Sanchez LA, Harrykissoon RI, Eichner ER. Sickle Cell Trait and Fatal Rhabdomyolysis in Football Training: A Case Study. Medicine & Science in Sports & Exercise. 2010;42(1):3–7.
References