Sickle Cell Anaemia

Sickle cell anaemia is a serious inherited blood disorder where red blood cells become rigid and crescent-shaped, blocking blood flow and causing pain, infections, and organ damage throughout life.

Table of contents

• What is sickle cell anaemia?
• What causes this condition?
• Common symptoms
• Different types of sickle cell disease
• Who is most affected?
• How is it diagnosed?
• Treatment options
• Living with sickle cell anaemia
• Outlook and life expectancy

What is sickle cell anaemia?

Sickle cell anaemia is the most severe form of a group of inherited blood disorders called sickle cell disease (SCD). This condition affects the shape and function of red blood cells, which are responsible for carrying oxygen throughout your body^[1][2].

Normally, red blood cells are round and flexible, like soft disks. They can easily move through even the smallest blood vessels to deliver oxygen to all your organs and tissues. However, in sickle cell anaemia, these cells become rigid, sticky, and shaped like a crescent moon or a farm tool called a sickle. This unusual shape gives the disease its name^[3][4].

The sickled cells cannot move smoothly through your blood vessels. Instead, they get stuck and block blood flow, which causes pain and prevents oxygen from reaching parts of your body. These abnormal cells also die much faster than healthy red blood cells. Normal red blood cells live for about 120 days, but sickled cells typically die in just 10 to 20 days. This leads to a constant shortage of red blood cells, a condition called anaemia, which makes people feel extremely tired^[1][6].

What causes this condition?

Sickle cell anaemia is caused by changes in a specific gene called the HBB gene. This gene contains instructions for making beta-globin, which is part of hemoglobin, the protein inside red blood cells that carries oxygen^[2][4].

The genetic change causes the body to produce abnormal hemoglobin called hemoglobin S. This abnormal hemoglobin makes red blood cells become rigid and sickle-shaped, especially when they release oxygen to the body’s tissues^[3].

You can only be born with sickle cell anaemia if you inherit the changed gene from both of your biological parents. If both parents have either sickle cell disease or carry the sickle cell gene, there is a 1 in 4 chance that each of their children will have sickle cell disease^[5][6].

People who inherit the gene from only one parent have what is called sickle cell trait. They usually do not have symptoms of the disease but can pass the gene to their children^[3][6].

Common symptoms

Symptoms of sickle cell anaemia typically appear when babies are around 5 to 6 months old. The signs vary from person to person and may change over time^[1][4].

The most common symptoms include:

• Extreme tiredness and fatigue: Because there are not enough healthy red blood cells to carry oxygen, people feel very tired and weak. Babies may seem unusually fussy and irritable^[1][4].
• Painful episodes (pain crises): When sickled cells block blood flow through small blood vessels, it causes sudden, severe pain. This pain can occur in the arms, legs, chest, back, and joints. The pain may start as an ache that gets worse or come on suddenly. Some people have only a few pain crises each year, while others may have many. These episodes can last from a few hours to several days^[1][2].
• Frequent infections: Sickle cell anaemia affects the spleen, an organ that helps fight infections. When the spleen is damaged, the body becomes more vulnerable to infections, especially in young children^[1][4].
• Swelling of hands and feet: This is often one of the first signs of sickle cell anaemia in babies. The swelling occurs when sickled cells block blood flow to the hands and feet, causing painful swelling^[1][4].
• Yellow skin and eyes (jaundice): The rapid breakdown of sickled cells releases a substance called bilirubin into the blood. When bilirubin builds up, it causes the skin and the whites of the eyes to turn yellow^[1][4].

Long-term complications from sickle cell anaemia can include strokes, lung problems, eye problems, organ damage, and kidney disease. Any fever in someone with sickle cell disease must be taken very seriously because it may signal a dangerous infection^[1][2][12].

Different types of sickle cell disease

Sickle cell disease includes several types, depending on which genes a person inherits from their parents^[3]:

• HbSS (Sickle cell anaemia): This is the most common and usually the most severe form. People inherit two hemoglobin S genes, one from each parent^[3].
• HbSC: People inherit one hemoglobin S gene from one parent and a gene for another abnormal hemoglobin called “C” from the other parent. This is usually a milder form of the disease^[3].
• HbS beta thalassemia: People inherit one hemoglobin S gene and one gene for beta thalassemia, another blood disorder. There are two types: HbS beta0-thalassemia, which is usually severe, and HbS beta+-thalassemia, which tends to be milder^[3].
• Rare types: These include HbSD, HbSE, and HbSO. The severity of these rarer types varies^[3].

Who is most affected?

Sickle cell anaemia affects approximately 100,000 people in the United States. The condition is much more common in certain ethnic groups^[4][6]:

• People of African descent, including African-Americans (about 1 in 365 Black people in the US have the disease, and 1 in 12 carry the gene)^[4][6]
• Hispanic-Americans, particularly those from Central and South America^[6]
• People with southern European, Middle Eastern, or Asian Indian ancestry^[4][6]

The condition is also common in people with Caribbean family backgrounds^[5].

How is it diagnosed?

In the United States, all newborn babies are tested for sickle cell disease as part of routine newborn screening. A small blood sample is taken from the baby’s heel shortly after birth. This early detection allows doctors to start treatment right away, which helps prevent serious complications^[1][3][9].

Older children and adults can also be tested for sickle cell disease with a simple blood test. The blood sample is sent to a laboratory where it is checked for the presence of hemoglobin S^[1][9].

If someone is diagnosed with sickle cell anaemia, doctors may recommend additional tests to check for complications. These may include ultrasound tests to assess stroke risk in children, as well as blood tests and imaging studies to monitor organ function^[9].

Sickle cell disease can also be diagnosed before birth through tests that examine the amniotic fluid (the fluid surrounding the baby in the womb) or tissue from the placenta. If you or your partner has sickle cell disease or carries the gene, you can talk to a genetic counselor before pregnancy to understand your options^[9].

Treatment options

While there is currently no widely available cure for sickle cell anaemia, many treatments can help manage symptoms, prevent complications, and improve quality of life. Treatment focuses on relieving pain, avoiding crises, and preventing infections and organ damage^[1][2].

Medicines

Several medicines are approved to treat sickle cell disease:

• Hydroxyurea: This daily medicine reduces the frequency of painful crises and may decrease the need for blood transfusions and hospital stays. It has been used since 1998 and is recommended for many patients, including young children^[9][10].
• L-glutamine: This medicine, available as a powder that can be mixed with food or water, was approved in 2017 for patients five years and older. It helps reduce pain episodes^[10][12].
• Crizanlizumab: This medicine is given through monthly infusions and was approved in 2019 for patients 16 years and older to reduce pain crises^[10][12].
• Pain medicines: Over-the-counter pain relievers like paracetamol or ibuprofen can help with mild to moderate pain. For severe pain crises, stronger prescription painkillers may be needed, sometimes requiring hospital treatment^[9][13].
• Antibiotics: Daily antibiotics, usually penicillin, are given to young children to prevent dangerous infections. This is especially important until at least age 5, and some people continue taking antibiotics throughout their lives^[9][13][14].

Blood transfusions

Blood transfusions increase the number of healthy red blood cells in the body, which helps reduce symptoms and prevent complications like stroke. Some people need transfusions regularly, while others may need them only during emergencies or severe complications^[9][10].

Preventing infections

Because people with sickle cell disease are more vulnerable to infections, it is very important to:

• Receive all recommended vaccinations, including annual flu shots and vaccines for pneumonia and meningitis
• Take daily antibiotics as prescribed, especially for young children
• Seek medical care immediately for any fever or signs of infection^[10][13][14]

Stem cell transplant

A stem cell transplant (also called a bone marrow transplant) is currently the only cure for sickle cell disease. However, it is not an option for most people because the procedure carries significant risks and requires a closely matched donor, usually a family member. The decision to proceed with a transplant depends on many factors, including age and the severity of symptoms^[6][9][13].

Gene therapy

In December 2023, the U.S. Food and Drug Administration approved two new gene therapies for sickle cell disease. These treatments work by either adding a modified gene into the body or changing a gene that is already there. These are transformative therapies that may offer cures for some patients with sickle cell disease^[10][12].

Living with sickle cell anaemia

People with sickle cell anaemia can live full lives and participate in most activities that other people enjoy. Managing the condition requires ongoing care and attention to preventing crises and complications^[2][16].

Healthy habits to prevent crises

You can reduce your risk of painful episodes by avoiding things that trigger them:

• Stay hydrated: Drink 8 to 10 glasses of water every day. Dehydration increases the risk of a crisis^[16][17].
• Avoid extreme temperatures: Dress appropriately for the weather and avoid sudden temperature changes, such as swimming in cold water. Don’t get too hot or too cold^[16][17].
• Be careful at high altitudes: The lower oxygen levels at high altitudes can trigger a crisis. Flying in airplanes should not be a problem because cabins are pressurized^[16][17].
• Exercise moderately: Physical activity is important for staying healthy, but avoid very intense exercise that leaves you seriously out of breath. Rest when you feel tired^[16][17].
• Avoid alcohol and smoking: Alcohol can cause dehydration, and smoking can trigger serious lung complications^[17].
• Manage stress: Stress can trigger a crisis. Learning relaxation techniques like breathing exercises may help^[17].

Regular medical care

People with sickle cell disease should see their doctor regularly for checkups, usually every 3 to 12 months depending on age and the severity of the disease. Regular care helps prevent serious problems and allows early treatment of complications^[16].

It is important to take all prescribed medicines as directed and to work closely with your healthcare team. The best care often comes from specialists at sickle cell treatment centers^[2][16].

When to seek emergency care

Contact your doctor or go to the emergency room immediately if you experience:

• A fever over 38°C (or any increased temperature in a child)
• Severe pain that is not responding to home treatment
• Severe vomiting or diarrhea
• Severe headache, dizziness, or stiff neck
• Breathing difficulties
• Very pale skin or lips
• Sudden swelling in the abdomen
• Confusion, drowsiness, or slurred speech
• Weakness on one or both sides of the body
• Changes in vision or sudden vision loss^[17]

Outlook and life expectancy

Sickle cell disease varies greatly from person to person, ranging from mild to severe. In the past, babies born with sickle cell anaemia rarely lived to become adults. However, thanks to early detection through newborn screening and advances in treatment, outcomes have improved dramatically^[4][5].

Today, with proper care, many people with sickle cell anaemia live into their 50s and beyond. Some people experience mild symptoms and lead relatively normal lives most of the time, while others face more frequent and serious complications^[4][5].

The key to the best possible outcome is early diagnosis, regular medical care, following treatment plans, and working with a team of healthcare specialists who understand sickle cell disease. With the right support and management, people with sickle cell anaemia can live fulfilling lives^[2][5].