Sickle cell disease (SCD) is an inherited disorder. In SCD, a mutation in a gene that makes hemoglobin (the protein that gives red blood cells their color) changes the shape of red blood cells from round to the shape of a C-shaped farm tool called a “sickle”. This can cause a lot of health problems.

Normal red blood cells are donut-shaped, squeezable, flexible cells that contain hemoglobin. They deliver oxygen all over the body. Red blood cells pick up the oxygen in the lungs and carry it through the blood vessels to all the tissues in your body. In someone who has SCD, more than half of the hemoglobin has a mutation. The mutated hemoglobin is called sickle cell hemoglobin (HbS).^1–5 This mutation makes the altered hemoglobin (hemoglobin S) stack in long strings inside blood cells, forming hemoglobin chains that damage the red blood cells and change their shape from round to sickle-shaped. These deformed blood cells (sickle cells) do not live as long as healthy red blood cells.6 As a result, people with SCD may not have enough red blood cells to give their bodies an adequate supply of oxygen.⁷ Continuous breakdown of sickle cells can cause chronic inflammation in the blood vessels⁸, and the lack of oxygen and nutrients can damage tissues and organs.⁶ 

"Sickle cell anemia" is a common term but does not cover all the aspects of the disease. “Anemia” only means the shortage of red blood cells due to the shorter lifespan of the red blood cells that have turned into sickle cells. But sickle cell disease is more than that. Another typical feature of SCD is that sickle cells can stick together and block blood flow in blood vessels.

People with SCD have an abnormality in a gene that is involved in making hemoglobin. This abnormality is called a “point mutation” because only a single site in the gene is altered.¹ The rest of the gene is the same as a healthy gene. The abnormal sickle cell gene is called the hemoglobin S gene (HbS). If more than half of all the hemoglobin in your body is abnormal, you will get sickle cell disease.³

Usually, a person gets sickle cell disease only if they are born with two copies of a sickle cell gene. Sometimes a person can have one sickle cell gene and another abnormal gene (such as HbC or beta-thalassemia). These cases are still called sickle cell disease. To have sickle cell disease, a child needs to inherit one abnormal gene from each parent. People who have one sickle cell gene and one healthy gene have “trait” SCD. They do not get the disease⁶ but are carriers and can pass the abnormal gene to their children. If both parents carry an altered gene, there is a 25% chance that their children will get sickle cell disease. That’s why there are often children with SCD and healthy siblings in one family.⁶

• there is not enough hemoglobin to supply the body with oxygen 
• sickle cells can damage and block blood vessels 
• chronic infections occur.

• Some people have hardly any symptoms until well into adulthood, while others have serious problems early in life.³
• The first signs of SCD often appear when a baby is two to three months old. That’s because babies have a different form of hemoglobin until that age.²
• SCD symptoms can change in the course of a person’s life.
• The frequency or likelihood of certain health problems may be different in children and adults.^6,16

Healthy red blood cells live for about 120 days before they die.⁶ Sickle cells have a much shorter lifespan of only 10 to 20 days.⁶ This can lead to a shortage of the red blood cells and hemoglobin needed to supply all of your tissues with sufficient oxygen.⁷ This type of anemia is also known as hemolytic anemia. People with SCD have anemia all their lives.² Fatigue (extreme tiredness, physical and mental exhaustion) is a serious and common symptom of anemia.^17,18 Other symptoms include:

• Paleness (pallor)⁶
• Getting tired easily⁶
• Feeling irritable⁶
• Low appetite or no appetite⁶
• Delayed growth⁶

Especially in babies and young kids, too many blood cells can suddenly get trapped in the spleen.⁷ This is called splenic sequestration. The spleen swells, resulting in very severe anemia. This condition is a medical emergency that needs to be treated immediately.⁷

Parents need to learn to feel the size of the spleen and recognize an enlarged spleen in their child with SCD. A child with an enlarged spleen needs to be taken to hospital immediately.⁷ Call 112 right away! Splenic sequestration can also occur into adulthood.⁴

The most common symptom of SCD is pain.³ Periods of pain occur at regular intervals. The pain can be excruciating.^6,9 If not treated properly, it can become chronic.³ 

Sickle cells are stiffer than healthy red blood cells, meaning they are less flexible1 and less able to squeeze through the smallest blood vessels.²⁵ If a large part of the blood is made up of sickle cells, the blood flows more slowly because the sickle cells repeatedly stick to blood vessel walls.²⁶ Sickle cells break down faster (hemolysis), triggering chronic (lasting) blood vessel inflammation.²⁶ Also, sickle cells can clump together and block blood vessels (vascular occlusion).⁶ Tissues and organs receiving their blood supply through these blood vessels no longer get enough oxygen and nutrients, causing what is known as a vaso-occlusive event or pain crisis.²⁵ A pain crisis can happen at any time. The pain can be extreme and can affect any part of the body, especially the legs, back, abdomen, chest and head.^6,25 If not treated properly, the pain can become chronic.³ That’s why careful, long-term and regular treatment of sickle cell disease is so important.

Sickle cell disease is a condition that can damage many organs in the body. The main health issues arise from the early, uncontrolled breakdown of red blood cells and the stiffness of sickle cells.

Many of the serious health problems in SCD are due to the blockage of blood vessels by sickle cells, constant anemia and pain crises.⁶ And if you have SCD, your blood may already be low in oxygen because of the anemia.⁶ This can cause tissue damage sooner or later. Any organ can be affected, including the liver, lungs, spleen, kidneys, heart, skin and eyes.^3,6

Joint and bone tissue may die if it is not getting any oxygen because sickle cells are blocking the blood vessels. The hip and shoulder joints are particularly at risk.⁹ 

Infections caused by bacteria or viruses are more common and more severe in people with SCD.¹⁶ That’s because the spleen – which is important for fighting infections – may be damaged by SCD very early in life.⁹ Babies and kids under 5 are at higher risk of life-threatening infections in the lungs, blood, meninges and bones caused by bacteria.⁶

A high temperature in a person with SCD should always be taken seriously. Any child under 5 with SCD and a temperature over 38.5 degrees Celsius needs to be hospitalized.¹⁶ Older children and adults with a fever need to get checked by a doctor immediately.

SCD is a chronic condition. People with SCD have it for life. And need lifelong medical care. If SCD is found and treated early, it helps people live longer.⁶ And there are things you can do to prevent serious health impacts. With good care, around 85% of kids with sickle cell disease now reach adulthood.²⁰ 

Ideally, treatment should be shared by a specialized team working together with a pediatrician or family doctor. 

• Stay hydrated! Tap water and unsweetened teas are best
• Avoid smoking and alcohol
• Do not swim in cold water
• Stick to a healthy, balanced diet 
• Keep vaccines up to date
• Always have painkillers handy
• Tell your friends, neighbors and work about your sickle cell disease. And let them know how they can help in an emergency.