What is Sickle Cell Disease?

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Sickle cell disease (SCD) is an umbrella term for a group of genetic disorders affecting the body’s red blood cells.

People with SCD have atypical hemoglobin, a protein within red blood cells that helps circulate oxygen throughout the body – known as hemoglobin S or sickle hemoglobin – which causes their red blood cells to become misshapen. As a result, these red blood cells break down more quickly than usual and can block small blood vessels, cutting off the oxygen supply to certain tissues and causing complications.^[1]

SCD is typically a serious and lifelong condition, requiring long-term treatment and management. The disorder is most common in people of African, Caribbean, Middle Eastern, Eastern Mediterranean, and Asian origin.^[2]

Types of sickle cell disease

There are seven main subtypes of sickle cell disease:^[3][^10]^[4]

• HbSS (commonly known as sickle cell anemia)
• HbSC
• HbS beta-thalassemia
• HbSD
• HbSE
• HbSO
• HbAS

In all of these subtypes, “Hb” stands for “hemoglobin”. All sickle cell diseases are hereditary hemoglobinopathies, which means that a person has inherited genetic deformations of hemoglobin from one or both parents.^[4] Most of these subtypes don’t have “common” names and are therefore usually called by their abbreviations. The exception is sickle cell anemia.

HbSS, or sickle cell anemia, is the most common subtype of sickle cell disease. In this subtype, the affected person inherits one sickle-cell gene from each parent. This is called homozygous sickle cell disease.[^10]

In HbSC, the affected person inherits a sickle cell gene from one parent and a gene for a defective form of hemoglobin, hemoglobin-C, from the other.^[4]

HbS beta-thalassemia comes in two forms, beta 0-thalassemia, which is quite severe, and beta +-thalassemia, which is milder. These occur when the affected person has inherited a sickle-cell gene from one parent and a beta-thalassemia gene from the other.^[3][^10]

HSD, HbSE, and HbSO are rarer subtypes of sickle cell disease. In these subtypes, the affected person has inherited a sickle-cell gene from one parent and a gene for a defective form of hemoglobin (Hemoglobin D, E, or O) from the other. The severity of these subtypes varies.^[3]

Individuals who have only inherited a sickle-cell gene from one parent and no abnormal genes from the other have what is known as the sickle-cell trait.[4] In these cases, they are unaffected by the abnormal gene but may pass on risk of sickle-cell disease to their children.[3] If two people with the sickle-cell trait have children, those children have a one in four chance of having sickle-cell disease, a one in four chance of being completely unaffected, and a one in two chance of being unaffected carrier themselves.

If you suspect you or a loved one may have sickle cell disease, . check your symptoms atAdoctor symptoms.

Symptoms of sickle cell disease

The symptoms of SCD are typically intermittent, meaning they are experienced in episodes that come and go. Symptoms also tend to vary in frequency and severity from person to person and may change over time. They can occur in conditions that cause hypoxia, such as intense physical exertion.

Symptoms of SCD may include:^[5][6][7]

Painful episodes

Episodes of pain – also known as sickle cell crises – are one of the most common symptoms of SCD. The pain can vary in severity and may come on suddenly. Most often it is felt in the bones and joints, though it may also occur in other locations, such as the hands, feet, arms, legs or abdomen. Any area with both sensory nerves and blood supply can be affected during a painful episode. Many people with SCD experience chronic, low-level pain, often in bones and joints.

Painful episodes are caused by sickle-shaped cells blocking blood vessels and cutting off the oxygen supply to tissues. Although it is not clear what brings on these episodes, it is thought that changes in the weather, dehydration, stress, and strenuous exercise can all act as triggers.

Acute chest syndrome

Acute chest syndrome occurs when blood vessels in the lungs become blocked, typically causing chest pain, a high temperature, coughing, and shortness of breath. It should be treated as a medical emergency requiring urgent treatment. Symptoms of acute chest syndrome are:

• Chest pain, most common in adults
• Coughing
• Shortness of breath, most common in adults
• Fever, more common in children

The cause of acute chest syndrome may be multifactorial and may include factors, such as:

• Infection
• Blocked blood vessels
• Shallow inhalation, which can lead to poor ventilation in the lung
• Obstruction of blood supply (infarction) to the ribs

Infections

People with SCD are susceptible to severe infection from certain types of bacteria. Common types of infection include:

• Blood infection, also known as septicemia
• Lung infection, also known as pneumonia
• Infection of the surroundings of the brain and the spine, also known as bacterial meningitis
• Bone infection, also known as osteomyelitis

Good to know: Infection, particularly in infants, should be treated as a medical emergency requiring urgent treatment.

Severe anemia

People with SCD will normally also experience mild to moderate anemia, a lack of hemoglobin. Periodically, however, this anemia can become severe and require urgent medical attention. This may occur suddenly or more gradually.

Signs and symptoms of the onset of severe anemia include:

• Tiredness
• Shortness of breath
• Dizziness
• Nausea
• Paleness, particularly in the eyelids, lips, tongue and fingernails

Read more about Anemia »

Signs and symptoms of sickle cell disease in infants

As a genetic disorder, SCD is present from birth, but will not generally begin to display symptoms until an infant is 5 to 6 months old. However, in some areas, routine newborn screening may find the disease.

Early signs and symptoms that may indicate the presence of SCD include:

• Swelling of the hands and feet that may cause pain, also known as dactylitis
• Fatigue, fussiness and irritability
• A yellowing of the skin and/or whites of the eyes, also known as jaundice

If you are concerned your infant is displaying signs of sickle cell disease, contact your doctor Find My doctor location to start a free symptom assessment.

Causes of sickle cell disease

SCD is caused by a gene defect that creates atypical hemoglobin, known as hemoglobin S or sickle hemoglobin. Hemoglobin S behaves differently from normal hemoglobin, typically changing the shape of red blood cells from their usual spherical, donut-like shape, into a crescent or sickle-like shape.

These deformed red blood cells tend to deplete faster than usual, causing anemia and can block blood vessels, leading to a reduced supply of oxygen to the body’s tissues.^[5]

How is sickle cell disease inherited?

If an individual inherits two hemoglobin S genes from their parents, that person may develop SCD. This may also be the case if an individual inherits one hemoglobin S gene plus another type of abnormal hemoglobin gene, such as thalassemia, hemoglobin C, hemoglobin D or hemoglobin E.^[8]

If an individual inherits one hemoglobin S gene and one normal hemoglobin gene from their parents, they will have something known as sickle cell trait and become a carrier of sickle cell disease. People with sickle cell trait, however, will generally be healthy and only rarely display signs or symptoms associated with SCD. These symptoms can occur during intense exercise or physical exertion.

Diagnosing sickle cell disease

SCD is normally diagnosed following blood tests. To make the diagnosis, a blood sample will be taken and analyzed in order to establish what type of hemoglobin is present.

If the results prove inconclusive or there is any uncertainty, DNA tests may also be carried out.^[9]

Diagnosing sickle cell disease in newborn babies

In many places, tests for sickle cell disease are carried out on newborn babies as part of the routine postnatal screening process. To do this, a blood sample will be collected from a heel prick and sent to a laboratory for testing.

Parents will be informed of the results of the testing as soon as possible. If the results return positive for SCD, the second round of testing will be ordered to definitively confirm the diagnosis. If confirmed, parents will have treatment options thoroughly explained to them.

Good to know: Postnatal tests will also be able to show whether or not a newborn has a sickle cell trait. This is important, as it may increase the chances of a sibling or the child’s future children inheriting the disorder.^[10]

Prenatal sickle cell disease diagnosis

Tests can also be carried out prior to birth to see whether a child will inherit SCD. This is usually done by using tissue from the placenta or amniotic fluid from the sac surrounding the embryo and can be carried out from around 8 to 10 weeks into the course of a pregnancy.

Sickle cell disease treatment

A number of treatment methods are available to manage the symptoms of SCD and prevent complications. However, in most cases, the **disorder cannot be cured and will **require lifelong management.

People with SCD will be treated by a specialist and will be required to attend check-ups at regular intervals. They will also be taught how to recognize the condition’s symptoms so that treatment can be given as soon as possible after they appear.

Staying healthy is an important principle of managing SCD. This will often involve:^[5]

• Antibiotics. Taking daily doses of antibiotics, usually penicillin, is often recommended by doctors, particularly for children of five years of age or younger. This is aimed at preventing infection.
• Vaccinations. People with SCD, especially children, should ensure they keep up-to-date with all recommended vaccinations, including those against meningitis, influenza and hepatitis B.
• Vitamin supplements. Extra folic acid supplements are commonly recommended for people with SCD to aid the body in its production of red blood cells. A daily supplement containing zinc, Vitamins D, E, C and A, magnesium, selenium, carotenoids and flavonoids, but not iron, may also be useful.

Treating painful episodes

Most mild to moderate painful episodes (sickle cell crises) will not require a visit to the hospital and can be treated at home. This may involve:

• Painkillers, usually paracetamol or ibuprofen
• Staying hydrated by drinking plenty of water
• Antibiotics. These are strongly recommended for children of younger than five, but are optional for older individuals. Should a fever develop, the individual should receive prompt medical attention regardless of whether or not they are on antibiotics

If a painful episode is severe, professional medical attention should be sought as soon as possible. If fever appears, medical attention should be sought right away: fever is a medical emergency in people with SCD.

Hydroxyurea therapy

In people with frequent and severe pain resulting from SCD, hydroxyurea treatment is currently the standard. Hydroxyurea increases the concentration of functioning hemoglobin. This in turn reduces painful episodes and acute chest syndrome, as well as the need for hospitalization and the number of blood transfusions a person with SCD may need.^[11]

Blood transfusions

A blood transfusion can be used to treat acute chest syndrome or severe anemia, as well as to prevent or treat certain complications. Blood transfusions, however, are not considered routine due to the complications they can cause, meaning they are only carried out when considered absolutely necessary.

Treatment to prevent clotting is recommended for all adults with SCD admitted to the hospital.

Stem cell transplant

A stem cell transplant is the only known way to cure SCD. It does, however, come with the risk of severe complications, and its success is not guaranteed. It is generally reserved for very severe cases of SCD.

Erythrocytapheresis

Erythrocytapheresis is a method of reducing hemoglobin concentration to less than 30%. In this procedure, red blood cells are removed from a blood sample, and the rest of the blood is introduced to circulation.^[12]

In this way, it cuts down the risk of stroke in adults and children from SBC. The treatment has relatively few side effects, all of which can be managed.

Sickle cell disease complications

There are various possible complications that can occur as a result of SCD. Some of the most common complications related to SCD include:

Growth and development problems

Children and adolescents with SCD may experience slowed growth and development. Teenagers may also undergo puberty two to three years later than average. Doctors will monitor childhood development closely and may suggest certain vitamin supplements to help manage possible problems.

Stroke

Strokes are a common complication for children and adolescents with SCD and can occur in adults.

Sickle cells blocking blood vessels in the brain can shut off the oxygen supply, causing a stroke. Symptoms may include difficulty with speech and weakness or paralysis of the face and limbs. In some cases, there may be no noticeable symptoms.

Strokes are generally treated with blood transfusions, which are able to improve blood flow to the brain.

Read more about Ischemic Stroke »

Spleen problems

If blood vessels in the spleen become blocked, the organ can swell with blood and cause a severe bout of anemia. This will often occur very suddenly and require urgent medical attention. In some cases, treatment may involve removing the spleen completely.

Other complications

Other possible complications include:

• Heart, lung or kidney problems
• Eye or vision problems
• Unwanted and sustained erections (priapism)
• Gallstones
• Leg ulcers

Sickle cell disease FAQs

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1. National Heart, Lung, and Blood Institute. “What is Sickle Cell Disease?” August 10, 2017. Accessed November 9, 2017. ↩

2. NHS Choices. “Sickle cell disease.” May 17, 2017. Accessed November 9, 2017. ↩

3. Centers for Disease Control and Prevention. “Facts About Sickle Cell Disease”. Accessed 04 April 2018.
   [10]: Sickle Cell Association of the National Capital Area, Inc. “Types of Sickle Cell Disease”. Accessed 04 April 2018. ↩ ↩ ↩ ↩

4. AMBOSS. “Sickle cell anemia (Sickle cell disease)”. Accessed 04 April 2018. ↩ ↩ ↩ ↩

5. Patient. “Sickle Cell Disease.” November 1, 2017. Accessed November 9, 2017. ↩ ↩ ↩

6. NHS Choices. “Sickle cell disease: Symptoms.” May 17, 2016. Accessed November 9, 2017. ↩

7. National Heart, Lung, and Blood Institute. “What Are the Signs and Symptoms of Sickle Cell Disease.” August 10, 2017. Accessed November 9, 2017. ↩

8. National Heart, Lung, and Blood Institute. “What Causes Sickle Cell Disease?” August 10, 2017. ↩

9. Patient. “Diagnosing Sickle Cell Disease.” November 1, 2017. Accessed November 9, 2017. ↩

10. National Heart, Lung, and Blood Institute. “How is Sickle Cell Disease Diagnosed.” August 10, 2017. Accessed November 9, 2017. ↩

11. Medscape. “Sickle Cell Anemia Treatment & Management.”. December 27, 2017. Accessed May 4, 2018. ↩

12. Tranfusion Medicine and Hemotherapy. “Erythrocytapheresis: Do Not Forget a Useful Therapy!”. Januiary 15, 2008. Accessed 4 May, 2018. ↩

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**What is Sickle Cell Disease?**



**Overview**



Sickle cell disease (SCD) ⁣is a rare and inherited blood disorder characterized by abnormal, sickle-shaped red blood cells. ​These misshapen cells can obstruct blood flow, causing a variety ‍of health complications. SCD primarily affects individuals of African, Hispanic, and ⁤Mediterranean ancestry.



**Causes**



SCD⁣ is ‍caused by a‍ mutation in the hemoglobin gene (HBB), which encodes the⁣ protein​ responsible for carrying oxygen‌ in red blood cells. The mutation ​causes red blood cells to produce defective hemoglobin called sickle hemoglobin (HbS).



**Symptoms**



SCD‍ symptoms can range from⁤ mild to​ life-threatening and can include:



* Chronic pain episodes (sickle cell ‌crises)

* Anemia

*⁢ Fatigue

* Jaundice (yellowing of ​the skin​ or eyes)

* Organ ‍damage (e.g., stroke, ‍heart attack, kidney failure)



**Types**



There are several types of SCD, the most common being:



* Hemoglobin ⁤SS disease: The ⁢most severe form,‌ caused​ by ⁣two copies of the⁤ HbS gene

*​ Hemoglobin SC disease: Caused by one‌ copy of the HbS gene⁣ and one ​copy ​of the hemoglobin C (HbC) gene

* Hemoglobin Sβ-Thalassemia: Caused by the HbS gene⁤ and a mutation in the beta-globin gene



**Diagnosis**



SCD is‍ diagnosed based on a blood test that detects​ the⁣ presence of sickle hemoglobin. Additional tests, such as electrophoresis or genetic testing, may be ⁤used to confirm the diagnosis and identify the specific type ​of‍ SCD.



**Treatment**



There is currently no cure for SCD, but ‍treatments aim to manage symptoms, prevent complications, and improve quality of ⁣life. These include:



* Pain medication

* ‍Blood transfusions

* Hydroxyurea (hydroxycarbamide)

* Stem cell transplant

* Gene therapy



**Prevention**



Preventing⁣ SCD involves genetic counseling and‍ prenatal screening for individuals from high-risk populations. Screening can identify couples at risk of having children ‌with SCD and provide them with options for avoiding the condition.



**Outlook**



The outlook for individuals with SCD has improved significantly in recent years due to advances⁤ in⁢ treatment. With proper management, individuals can lead healthy and fulfilling lives. However, SCD⁣ can still be ‍a life-threatening condition, and⁢ ongoing ⁣research is aimed at developing new and improved therapies.



**Additional ‌Keywords**



* Hematologic Disorder

* Genetic Mutation

* Sickle-Shaped Red Blood Cells

* Hemoglobin

*​ Sickle Cell Crises

* Pain ‌Management

* Blood ‍Transfusion

* Stem Cell Transplant

* Gene Therapy

* Genetic ‍Counseling

* ‌Prenatal Screening