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{{Sickle-cell disease}} | {{Sickle-cell disease}} | ||
{{CMG}}; {{AE}} {{AN}} | {{CMG}}; {{AE}} {{AN}}, {{shyam}} | ||
==Overview== | ==Overview== | ||
'''Sickle-cell disease''' is a group of [[genetic disorders]] of the red blood cell caused by a mutation in the β-globin chain gene of [[hemoglobin]] at the 6th position replacing [[glutamic acid]] to [[valine]]. HbS polymerizes reversibly when deoxygenated to form a network of fibrous [[hemoglobin]] polymers that stiffens the RBC [[Cell membrane|membrane]], giving it a sickle shape. These sickled cells loose the pliability to cross thin capillaries and possess a sticky membrane, giving it a property to adhere to the [[endothelium]] of blood vessels, thereby causing vaso-occlusion. It causes significant morbidity and mortality, particularly in people in the Mediterranean and African region. | '''Sickle-cell disease''' is a group of [[genetic disorders]] of the [[red blood cell]] caused by a mutation in the β-globin chain gene of [[hemoglobin]] at the 6th position replacing [[glutamic acid]] to [[valine]]. HbS polymerizes reversibly when deoxygenated to form a network of fibrous [[hemoglobin]] polymers that stiffens the RBC [[Cell membrane|membrane]], giving it a sickle shape. These sickled cells loose the pliability to cross thin capillaries and possess a sticky membrane, giving it a property to adhere to the [[endothelium]] of blood vessels, thereby causing vaso-occlusion. It causes significant morbidity and mortality, particularly in people in the Mediterranean and African region. The treatment includes measures to avoid vaso-occlusion, such as avoidance of dehydration, low oxygen conditions, or cold weather. Hydroxyurea has been used to increase fetal hemoglobin production. | ||
==Historical Perspective== | ==Historical Perspective== | ||
Sickle-cell disease was first discovered by [[James Herrick]], an American cardiologist and professor of medicine, in 1910 following presentation by his intern Ernest Irons.<ref name="pmid19610078">{{cite journal| author=Kato GJ, Hebbel RP, Steinberg MH, Gladwin MT| title=Vasculopathy in sickle cell disease: Biology, pathophysiology, genetics, translational medicine, and new research directions. | journal=Am J Hematol | year= 2009 | volume= 84 | issue= 9 | pages= 618-25 | pmid=19610078 | doi=10.1002/ajh.21475 | pmc=3209715 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=19610078 }} </ref> In 1922, the phrase, "sickle-cell anemia," was first used by Verne Mason, M.D. at Johns Hopkins University to describe the shape of the red blood cells. | |||
==Classification== | ==Classification== | ||
Sickle-cell disease may be classified according to the number and type of the two alleles of beta-globin. Sickle-cell disease may also be classified as an [[autosomal recessive]] genetic disorder. Sickle cell disease does not have a traditional classification method, as is true for other hemoglobinopathies.<ref name="pmid23378597">{{cite journal| author=Forget BG, Bunn HF| title=Classification of the disorders of hemoglobin. | journal=Cold Spring Harb Perspect Med | year= 2013 | volume= 3 | issue= 2 | pages= a011684 | pmid=23378597 | doi=10.1101/cshperspect.a011684 | pmc=3552344 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23378597 }} </ref> However, there are a few particular subtypes. Each subtype is based on the number and type of hemoglobin allele(s). The letter S denotes an allele with the sickle cell mutation. The subtypes (and the associated disease in parentheses below) are as follows: | |||
:*HbSS (sickle cell anemia) | :*HbSS (sickle cell anemia) | ||
:*HbSC (milder form of sickle cell anemia) | :*HbSC (milder form of sickle cell anemia) | ||
| Line 17: | Line 24: | ||
*Other variants of sickle cell disease include HbSD, HbSE, or HbSO (one sickle cell gene and one other gene).<ref name="pmid23378597">{{cite journal| author=Forget BG, Bunn HF| title=Classification of the disorders of hemoglobin. | journal=Cold Spring Harb Perspect Med | year= 2013 | volume= 3 | issue= 2 | pages= a011684 | pmid=23378597 | doi=10.1101/cshperspect.a011684 | pmc=3552344 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23378597 }} </ref> | *Other variants of sickle cell disease include HbSD, HbSE, or HbSO (one sickle cell gene and one other gene).<ref name="pmid23378597">{{cite journal| author=Forget BG, Bunn HF| title=Classification of the disorders of hemoglobin. | journal=Cold Spring Harb Perspect Med | year= 2013 | volume= 3 | issue= 2 | pages= a011684 | pmid=23378597 | doi=10.1101/cshperspect.a011684 | pmc=3552344 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23378597 }} </ref> | ||
. | . | ||
==Pathophysiology== | ==Pathophysiology== | ||
The pathophysiology of sickle cell disease is based on a mutation in the beta-globin chain of hemoglobin, which leads to red blood cell sickling and vaso-occlusive crises. The pathogenesis of sickle cell disease is characterized by an amino acid substitution on the beta-globin chain on chromosome 11, resulting in red blood cell sickling and vaso-occlusive episodes in various organs. A mutation in beta-globin, namely a a point mutation in exon 1 that substitutes valine for glutamic acid, has been associated with the development of sickle cell disease, involving the [[hemoglobin]] synthesis pathway.<ref name="pmid22924029">{{cite journal| author=Ballas SK, Kesen MR, Goldberg MF, Lutty GA, Dampier C, Osunkwo I et al.| title=Beyond the definitions of the phenotypic complications of sickle cell disease: an update on management. | journal=ScientificWorldJournal | year= 2012 | volume= 2012 | issue= | pages= 949535 | pmid=22924029 | doi=10.1100/2012/949535 | pmc=3415156 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22924029 }} </ref> On microscopic analysis, a peripheral blood smear will show sickle-shaped red blood cells, which are the characteristic findings of sickle cell disease. In some cases, hemoglobin C crystals may be observed. The point mutation causes cells to sickle, resulting in decreased deformability and decreased passage of red blood cells through the vasculature.<ref name="pmid27063958">{{cite journal| author=Alapan Y, Kim C, Adhikari A, Gray KE, Gurkan-Cavusoglu E, Little JA et al.| title=Sickle cell disease biochip: a functional red blood cell adhesion assay for monitoring sickle cell disease. | journal=Transl Res | year= 2016 | volume= 173 | issue= | pages= 74-91.e8 | pmid=27063958 | doi=10.1016/j.trsl.2016.03.008 | pmc=4959913 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=27063958 }} </ref> | |||
On microscopic analysis, a peripheral blood smear will show sickle-shaped red blood cells, which are the characteristic findings of sickle cell disease. In some cases, hemoglobin C crystals | |||
==Causes== | ==Causes== | ||
Sickle cell disease is caused by a mutation in the beta-globin gene on chromosome 11. | |||
==Differentiating Sickle Cell Disease from other Diseases== | ==Differentiating Sickle Cell Disease from other Diseases== | ||
*Sickle cell disease must be differentiated from other diseases that cause fatigue, infection, bone pain, such as: | *Sickle cell disease must be differentiated from other diseases that cause [[fatigue]], infection, [[bone pain]], such as:<ref name="pmid19885711">{{cite journal| author=Hernigou P, Daltro G, Flouzat-Lachaniette CH, Roussignol X, Poignard A| title=Septic arthritis in adults with sickle cell disease often is associated with osteomyelitis or osteonecrosis. | journal=Clin Orthop Relat Res | year= 2010 | volume= 468 | issue= 6 | pages= 1676-81 | pmid=19885711 | doi=10.1007/s11999-009-1149-3 | pmc=2865595 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=19885711 }} </ref><ref name="pmid25742458">{{cite journal| author=Sankaran VG, Weiss MJ| title=Anemia: progress in molecular mechanisms and therapies. | journal=Nat Med | year= 2015 | volume= 21 | issue= 3 | pages= 221-30 | pmid=25742458 | doi=10.1038/nm.3814 | pmc=4452951 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=25742458 }} </ref> | ||
:* | :*[[Thalassemia]] | ||
:* | :*Acute [[leukemia]] | ||
:* | :*[[Autoimmune hemolytic anemia]] | ||
:*HbSC disease | :*HbSC disease | ||
:*HbS-beta-thalassemia | :*HbS-beta-thalassemia | ||
:* | :*Septic arthritis | ||
:* | :*[[Polycythemia vera]] | ||
:* | :*[[Systemic lupus erythematosus]] | ||
==Epidemiology and Demographics== | ==Epidemiology and Demographics== | ||
| Line 45: | Line 47: | ||
===Age=== | ===Age=== | ||
* | *Age is not a risk factor for sickle cell disease since this disease is inherited at birth. Unlike other diseases that increase with age, persons with sickle cell disease are born with the condition. | ||
===Gender=== | ===Gender=== | ||
| Line 52: | Line 54: | ||
===Race=== | ===Race=== | ||
*There is a racial predilection for sickle cell disease. | *There is a racial predilection for sickle cell disease. | ||
**Sickle cell disease usually affects individuals of the black race. | |||
*Sickle cell disease usually affects individuals of the black race. | **Sickle cell disease also affects persons of eastern Mediterranean descent and Middle Eastern descent. | ||
*Sickle cell disease also affects persons of eastern Mediterranean descent and Middle Eastern descent. | |||
==Risk Factors== | ==Risk Factors== | ||
The most potent risk factor in the development of sickle-cell disease is race, which include Africans, African Americans, Indians, and persons of Mediterranean descent. An additional risk factor is geographic location, with these locations containing the greatest occurrences of disease.<ref name="pmid25143960">{{cite journal| author=Makani J, Ofori-Acquah SF, Nnodu O, Wonkam A, Ohene-Frempong K| title=Sickle cell disease: new opportunities and challenges in Africa. | journal=ScientificWorldJournal | year= 2013 | volume= 2013 | issue= | pages= 193252 | pmid=25143960 | doi=10.1155/2013/193252 | pmc=3988892 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=25143960 }} </ref> | |||
==Screening== | |||
Sickle cell disease is currently a disease for which newborn screening is available, mandated, and routinely performed in the United States.<ref name="pmid21927581">{{cite journal| author=Brandow AM, Liem R| title="Sickle Cell Disease in the Emergency Department: Atypical Complications and Management" | journal=Clin Pediatr Emerg Med | year= 2011 | volume= 12 | issue= 3 | pages= 202-212 | pmid=21927581 | doi=10.1016/j.cpem.2011.07.003 | pmc=3172721 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21927581 }} </ref> | |||
== Natural History, Complications and Prognosis== | == Natural History, Complications and Prognosis== | ||
*The majority of patients with sickle cell disease remain asymptomatic until the second half of the first year of life. This is the time when fetal hemoglobin production declines such that sickled hemoglobin manifests clinically. | *The majority of patients with sickle cell disease remain asymptomatic until the second half of the first year of life. This is the time when fetal hemoglobin production declines such that sickled hemoglobin manifests clinically. | ||
*Early clinical features include painful crises, fatigue, shortness of breath | *If left untreated, sickle-cell disease can result in death. | ||
*Common complications | *Early clinical features include painful crises, [[fatigue]], and [[shortness of breath]]. | ||
*Prognosis is generally guarded | *Common complications include [[sepsis]], [[hypoxia]], tissue infarction, depression, and death.<ref name="pmid12911250">{{cite journal| author=Hasan SP, Hashmi S, Alhassen M, Lawson W, Castro O| title=Depression in sickle cell disease. | journal=J Natl Med Assoc | year= 2003 | volume= 95 | issue= 7 | pages= 533-7 | pmid=12911250 | doi= | pmc=2594635 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12911250 }} </ref> | ||
*Prognosis is generally guarded in the United States and poor in developing nations. | |||
== Diagnosis == | == Diagnosis == | ||
===Diagnostic Criteria=== | ===Diagnostic Criteria=== | ||
*The diagnosis of sickle cell disease is made when a person has: | *The diagnosis of sickle cell disease is made when a person has: | ||
:* | :*The characteristic genetic mutation (glutamic acid to valine) in beta-globin | ||
:* | :*Symptoms characteristic of sickle cell disease | ||
=== Symptoms === | === Symptoms === | ||
*Sickle cell disease is usually symptomatic. | *Sickle cell disease is usually symptomatic. | ||
Symptoms of sickle-cell disease include: | |||
*[[Pain and nociception|Pain]] and/or [[bone pain]] | |||
*[[Dactylitis]] | |||
*[[Blurry vision]] | |||
*[[priapism|Persistent and painful erection]] | |||
*[[Numbness]] | |||
*[[Tingling]] | |||
*Motor skill loss | |||
*[[aphasia|Speech deficits]] | |||
*[[Gait disturbance]] | |||
*Leg ulceration | |||
*[[Jaundice]] | |||
=== Physical Examination === | === Physical Examination === | ||
*Patients with | *Patients with sickle cell disease usually appear ill during times of acute exacerbation of painful crises. If patients are well controlled on their medications, they can appear clinically well. | ||
*Physical examination may be remarkable for: | *Physical examination may be remarkable for: | ||
:* | :*[[Hypotension]] | ||
:* | :*[[Tachycardia]] | ||
:* | :*[[Dehydration]] | ||
:* | :*Scleral icterus | ||
:* | :*[[Pallor]] (conjunctival, mucosal, and/or skin) | ||
:* | :*[[Fever]] | ||
:* | :*[[Otitis]]/[[sinusitis]] | ||
:* | :*[[Splenomegaly]] (due to extramedullary hematopoiesis) | ||
:* | :*[[Heart failure]] | ||
:* | :*Frontal and parietal bone bossing (due to extramedullary hematopoiesis) | ||
=== Laboratory Findings === | === Laboratory Findings === | ||
The most important laboratory test for sickle cell anemia is a complete blood count (CBC), specifically [[hemoglobin]] and [[hematocrit]]. Low hemoglobin (anemia) is due to the intrinsic nature of the disease. A positive peripheral blood smear showing sickle-shaped cells is characteristic of sickle cell disease. High total bilirubin with predominantly indirect bilirubin may suggest hemolysis, since bilirubin is a breakdown production of hemoglobin. High lactate dehydrogenase (LDH) may also be seen if there is hemolysis. High reticulocyte count may be seen if the bone marrow is attempting to compensate for the anemia. Low oxygen content on arterial blood gas (ABG) may be observed. | |||
Low hemoglobin (anemia) is due to the intrinsic nature of the disease. | |||
High total bilirubin with predominantly indirect bilirubin may suggest hemolysis, since bilirubin is a breakdown production of hemoglobin. High lactate dehydrogenase (LDH) may also be seen if there is hemolysis. | |||
High reticulocyte count may be seen if the bone marrow is attempting to compensate for the anemia. | |||
Low oxygen content on arterial blood gas (ABG) may be | |||
===Imaging Findings=== | ===Imaging Findings=== | ||
In some cases, plain imaging such as | *In some cases, plain imaging such as x ray can be useful, which may reveal subacute or chronic infarcts of the extremities or deformities. | ||
*MRI can show avascular necrosis of the leg. | *CT scan is useful for patients with suspected stroke due to vaso-occlusion. | ||
*MRI can show avascular necrosis of the leg. It can also show [[osteomyelitis]] and marrow hyperplasia. | |||
=== Other Diagnostic Studies === | === Other Diagnostic Studies === | ||
* | *Sickle cell disease does not require any additional diagnostic tests. Newborn screening accurately identifies patients with sickle cell disease. | ||
== Treatment == | == Treatment == | ||
=== Medical Therapy === | === Medical Therapy === | ||
* | |||
*The mainstay of therapy for sickle cell disease is supportive care. Supportive care includes pain control, transfusions, antibiotics if there is infection, hydration, and oxygenation. | |||
Specific therapies include hydroxyuea, which increases fetal hemoglobin production, exchange transfusions, and stem cell transplant. | |||
=== Surgery === | === Surgery === | ||
*Surgery | *Surgery has no significant role in sickle cell disease. | ||
=== Prevention === | === Prevention === | ||
*There are no primary preventive measures available for | *There are no primary preventive measures available for sickle cell disease. However, genetic counseling is an option. | ||
Hydroxyurea can prevent sickle cell crises by increasing fetal hemoglobin. Fetal hemoglobin protects against complications of anemia.<ref name="pmid23465615">{{cite journal| author=Ngo D, Bae H, Steinberg MH, Sebastiani P, Solovieff N, Baldwin CT et al.| title=Fetal hemoglobin in sickle cell anemia: genetic studies of the Arab-Indian haplotype. | journal=Blood Cells Mol Dis | year= 2013 | volume= 51 | issue= 1 | pages= 22-6 | pmid=23465615 | doi=10.1016/j.bcmd.2012.12.005 | pmc=3647015 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=23465615 }} </ref><ref name="pmid26576059">{{cite journal| author=Fitzhugh CD, Hsieh MM, Allen D, Coles WA, Seamon C, Ring M et al.| title=Hydroxyurea-Increased Fetal Hemoglobin Is Associated with Less Organ Damage and Longer Survival in Adults with Sickle Cell Anemia. | journal=PLoS One | year= 2015 | volume= 10 | issue= 11 | pages= e0141706 | pmid=26576059 | doi=10.1371/journal.pone.0141706 | pmc=4648496 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=26576059 }} </ref> | |||
==References== | ==References== | ||
{{reflist|2}} | {{reflist|2}} | ||
[[Category:FinalQCRequired]] | |||
Latest revision as of 14:06, 10 July 2017
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aarti Narayan, M.B.B.S [2], Shyam Patel [3]
Overview
Sickle-cell disease is a group of genetic disorders of the red blood cell caused by a mutation in the β-globin chain gene of hemoglobin at the 6th position replacing glutamic acid to valine. HbS polymerizes reversibly when deoxygenated to form a network of fibrous hemoglobin polymers that stiffens the RBC membrane, giving it a sickle shape. These sickled cells loose the pliability to cross thin capillaries and possess a sticky membrane, giving it a property to adhere to the endothelium of blood vessels, thereby causing vaso-occlusion. It causes significant morbidity and mortality, particularly in people in the Mediterranean and African region. The treatment includes measures to avoid vaso-occlusion, such as avoidance of dehydration, low oxygen conditions, or cold weather. Hydroxyurea has been used to increase fetal hemoglobin production.
Historical Perspective
Sickle-cell disease was first discovered by James Herrick, an American cardiologist and professor of medicine, in 1910 following presentation by his intern Ernest Irons.[1] In 1922, the phrase, "sickle-cell anemia," was first used by Verne Mason, M.D. at Johns Hopkins University to describe the shape of the red blood cells.
Classification
Sickle-cell disease may be classified according to the number and type of the two alleles of beta-globin. Sickle-cell disease may also be classified as an autosomal recessive genetic disorder. Sickle cell disease does not have a traditional classification method, as is true for other hemoglobinopathies.[2] However, there are a few particular subtypes. Each subtype is based on the number and type of hemoglobin allele(s). The letter S denotes an allele with the sickle cell mutation. The subtypes (and the associated disease in parentheses below) are as follows:
- HbSS (sickle cell anemia)
- HbSC (milder form of sickle cell anemia)
- HbAS (sickle cell trait)
- HbSB+thal (beta-thalassemia anemia)
- HbSB0thal (beta-thalassemia anemia)
- Other variants of sickle cell disease include HbSD, HbSE, or HbSO (one sickle cell gene and one other gene).[2]
.
Pathophysiology
The pathophysiology of sickle cell disease is based on a mutation in the beta-globin chain of hemoglobin, which leads to red blood cell sickling and vaso-occlusive crises. The pathogenesis of sickle cell disease is characterized by an amino acid substitution on the beta-globin chain on chromosome 11, resulting in red blood cell sickling and vaso-occlusive episodes in various organs. A mutation in beta-globin, namely a a point mutation in exon 1 that substitutes valine for glutamic acid, has been associated with the development of sickle cell disease, involving the hemoglobin synthesis pathway.[3] On microscopic analysis, a peripheral blood smear will show sickle-shaped red blood cells, which are the characteristic findings of sickle cell disease. In some cases, hemoglobin C crystals may be observed. The point mutation causes cells to sickle, resulting in decreased deformability and decreased passage of red blood cells through the vasculature.[4]
Causes
Sickle cell disease is caused by a mutation in the beta-globin gene on chromosome 11.
Differentiating Sickle Cell Disease from other Diseases
- Sickle cell disease must be differentiated from other diseases that cause fatigue, infection, bone pain, such as:[5][6]
- Thalassemia
- Acute leukemia
- Autoimmune hemolytic anemia
- HbSC disease
- HbS-beta-thalassemia
- Septic arthritis
- Polycythemia vera
- Systemic lupus erythematosus
Epidemiology and Demographics
- The prevalence of sickle cell disease is approximately 160 per 100,000 individuals worldwide at birth. The actual prevalence, however, is less given that people die from the disease at an early time point.
- Approximately 1 in 12 persons of African descent have sickle cell trait.
- Approximately 100,000 persons are living with sickle cell disease in the United States.
Age
- Age is not a risk factor for sickle cell disease since this disease is inherited at birth. Unlike other diseases that increase with age, persons with sickle cell disease are born with the condition.
Gender
- Sickle cell disease affects men and women equally. It is not an X-linked disease.
Race
- There is a racial predilection for sickle cell disease.
- Sickle cell disease usually affects individuals of the black race.
- Sickle cell disease also affects persons of eastern Mediterranean descent and Middle Eastern descent.
Risk Factors
The most potent risk factor in the development of sickle-cell disease is race, which include Africans, African Americans, Indians, and persons of Mediterranean descent. An additional risk factor is geographic location, with these locations containing the greatest occurrences of disease.[7]
Screening
Sickle cell disease is currently a disease for which newborn screening is available, mandated, and routinely performed in the United States.[8]
Natural History, Complications and Prognosis
- The majority of patients with sickle cell disease remain asymptomatic until the second half of the first year of life. This is the time when fetal hemoglobin production declines such that sickled hemoglobin manifests clinically.
- If left untreated, sickle-cell disease can result in death.
- Early clinical features include painful crises, fatigue, and shortness of breath.
- Common complications include sepsis, hypoxia, tissue infarction, depression, and death.[9]
- Prognosis is generally guarded in the United States and poor in developing nations.
Diagnosis
Diagnostic Criteria
- The diagnosis of sickle cell disease is made when a person has:
- The characteristic genetic mutation (glutamic acid to valine) in beta-globin
- Symptoms characteristic of sickle cell disease
Symptoms
- Sickle cell disease is usually symptomatic.
Symptoms of sickle-cell disease include:
- Pain and/or bone pain
- Dactylitis
- Blurry vision
- Persistent and painful erection
- Numbness
- Tingling
- Motor skill loss
- Speech deficits
- Gait disturbance
- Leg ulceration
- Jaundice
Physical Examination
- Patients with sickle cell disease usually appear ill during times of acute exacerbation of painful crises. If patients are well controlled on their medications, they can appear clinically well.
- Physical examination may be remarkable for:
- Hypotension
- Tachycardia
- Dehydration
- Scleral icterus
- Pallor (conjunctival, mucosal, and/or skin)
- Fever
- Otitis/sinusitis
- Splenomegaly (due to extramedullary hematopoiesis)
- Heart failure
- Frontal and parietal bone bossing (due to extramedullary hematopoiesis)
Laboratory Findings
The most important laboratory test for sickle cell anemia is a complete blood count (CBC), specifically hemoglobin and hematocrit. Low hemoglobin (anemia) is due to the intrinsic nature of the disease. A positive peripheral blood smear showing sickle-shaped cells is characteristic of sickle cell disease. High total bilirubin with predominantly indirect bilirubin may suggest hemolysis, since bilirubin is a breakdown production of hemoglobin. High lactate dehydrogenase (LDH) may also be seen if there is hemolysis. High reticulocyte count may be seen if the bone marrow is attempting to compensate for the anemia. Low oxygen content on arterial blood gas (ABG) may be observed.
Imaging Findings
- In some cases, plain imaging such as x ray can be useful, which may reveal subacute or chronic infarcts of the extremities or deformities.
- CT scan is useful for patients with suspected stroke due to vaso-occlusion.
- MRI can show avascular necrosis of the leg. It can also show osteomyelitis and marrow hyperplasia.
Other Diagnostic Studies
- Sickle cell disease does not require any additional diagnostic tests. Newborn screening accurately identifies patients with sickle cell disease.
Treatment
Medical Therapy
- The mainstay of therapy for sickle cell disease is supportive care. Supportive care includes pain control, transfusions, antibiotics if there is infection, hydration, and oxygenation.
Specific therapies include hydroxyuea, which increases fetal hemoglobin production, exchange transfusions, and stem cell transplant.
Surgery
- Surgery has no significant role in sickle cell disease.
Prevention
- There are no primary preventive measures available for sickle cell disease. However, genetic counseling is an option.
Hydroxyurea can prevent sickle cell crises by increasing fetal hemoglobin. Fetal hemoglobin protects against complications of anemia.[10][11]
References
- ↑ Kato GJ, Hebbel RP, Steinberg MH, Gladwin MT (2009). "Vasculopathy in sickle cell disease: Biology, pathophysiology, genetics, translational medicine, and new research directions". Am J Hematol. 84 (9): 618–25. doi:10.1002/ajh.21475. PMC 3209715. PMID 19610078.
- ↑ 2.0 2.1 Forget BG, Bunn HF (2013). "Classification of the disorders of hemoglobin". Cold Spring Harb Perspect Med. 3 (2): a011684. doi:10.1101/cshperspect.a011684. PMC 3552344. PMID 23378597.
- ↑ Ballas SK, Kesen MR, Goldberg MF, Lutty GA, Dampier C, Osunkwo I; et al. (2012). "Beyond the definitions of the phenotypic complications of sickle cell disease: an update on management". ScientificWorldJournal. 2012: 949535. doi:10.1100/2012/949535. PMC 3415156. PMID 22924029.
- ↑ Alapan Y, Kim C, Adhikari A, Gray KE, Gurkan-Cavusoglu E, Little JA; et al. (2016). "Sickle cell disease biochip: a functional red blood cell adhesion assay for monitoring sickle cell disease". Transl Res. 173: 74–91.e8. doi:10.1016/j.trsl.2016.03.008. PMC 4959913. PMID 27063958.
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