Sickle cell disease

Some people are born with a blood problem.

Their blood cells are not round. Instead, they look like a curved moon.

These moon shapes can get stuck. They block the small paths in the body. This can cause a lot of pain. It can also hurt the heart or lungs.

Children may feel pain in their hands and feet. This often starts when they are very young. Some people feel sick or tired too.

Doctors can help people stay well. They use medicine and special shots. Some people get new blood to help them.

Many people around the world have this. It is good to learn how to help.

Some people are born with a blood disorder. This is called sickle cell disease.

Inside our blood, red cells carry oxygen. They usually look like round saucers. But in this disease, the cells change shape. They become curved like a sickle moon.

These sickle shapes can cause big problems. They are not soft or flexible. They can get stuck in small blood vessels. This is called a vaso-occlusive crisis. This happens when cells block the flow of blood. It can cause extreme pain in the chest or legs.

People get this disease from their parents. They must inherit two abnormal genes. One gene comes from each parent. If you only have one abnormal gene, you are a carrier. Carriers usually do not feel sick.

Doctors use blood tests to find the disease. They can help with medicine or blood transfusions. New gene therapies are also being used now. These help by changing blood cells in the bone marrow. Many people around the world live with this condition.

Sickle cell disease is a group of inherited blood disorders. The most common type is called sickle cell anaemia. This condition affects how our red blood cells carry oxygen. Normally, these cells are shaped like round saucers. They are soft and flexible so they can move easily.

In this disease, the cells change their shape. They become stiff and curved like a sickle moon.

This change happens because of an abnormality in haemoglobin. Haemoglobin is the protein that holds onto oxygen.

This disease works through a specific change in the cells. A person must inherit two abnormal copies of a gene. They get one copy from each parent.

This abnormal gene creates something called haemoglobin S. This protein changes how the red blood cells behave. When oxygen levels change, the cells switch from round shapes to sickle shapes. This can be triggered by stress, cold, or dehydration. Once they change, the cells become rigid. They can no longer bend to fit through tiny paths.

These stiff cells can block small blood vessels called capillaries.

Doctors have been studying this for a long time. An American doctor named James B. Herrick first described it in 1910. Later, in 1949, E. A. Beet and J. V. Neel found how it is passed down. In 1954, scientists learned something very interesting about the genes. They found that people who carry just one abnormal gene have some protection against malaria. This might be why the gene stays in certain populations. This connection helps explain why the disease is found in many places.

Many people around the world live with this condition. About 7.7 million people are affected globally. Most cases, around 80 percent, occur in sub-Saharan Africa. It is also found in parts of India and Southern Europe. The disease can cause many different health problems. Some people feel pain in their joints or hands. Others may face serious issues with their heart, lungs, or kidneys. Without care, many do not reach adulthood. However, with good healthcare, people can live to be 58 to 66 years old.

Medical science is finding new ways to help. Doctors use blood tests to find the disease in babies. They use medicines, vaccinations, and blood transfusions to keep people healthy. In 2023, new gene therapies were approved. These treatments change blood-forming cells in the bone marrow. This is a big step for science. It shows how we can use biology to fix the tiny parts of our blood.

Sickle cell disease (SCD) is a group of inherited blood disorders. These disorders affect how hemoglobin works in red blood cells. Hemoglobin is the protein that carries oxygen through the body. The most common form is known as sickle cell anaemia. In this condition, red blood cells change their shape. Instead of being round and flexible, they become stiff and curved.

This shape resembles a sickle, which is a curved tool used in farming. Because these cells are rigid, they struggle to move through the body. This leads to serious health challenges for many people.

The disease is caused by a specific genetic mechanism. A person must inherit two abnormal copies of the β-globin gene. They receive one abnormal gene from each parent.

This pattern is called autosomal recessive inheritance. These genes cause the body to produce hemoglobin S (HbS). When oxygen levels drop, the HbS molecules undergo polymerization. This means they stick together into long, rigid structures.

These structures force the red blood cell to transform from a flexible saucer shape into a stiff sickle shape. This change can be triggered by dehydration, high altitude, stress, or temperature changes.

Once the cells become sickle-shaped, they cause several types of medical crises. A vaso-occlusive crisis (VOC) occurs when these stiff cells block capillaries. These tiny blood vessels are too narrow for the rigid cells to pass through. This blockage restricts blood flow, causing ischaemia, which is a lack of oxygen to tissues. This results in extreme pain in the chest, back, legs, or arms.

Another emergency is a splenic sequestration crisis. This happens when sickled cells block the spleen, which acts as a blood filter. The spleen can swell with blood, causing a dangerous drop in hemoglobin levels. This most commonly affects young children, often around 1.4 years of age.

Other serious complications can affect the entire body. Acute chest syndrome is a major concern involving the lungs. It is caused by a vaso-occlusive crisis in the lungs and accounts for about 25% of deaths. Aplastic crises can also occur if a person catches parvovirus B19. This virus attacks the cells that produce new red blood cells. Because people with SCD already have shorter red cell lifespans, this can lead to life-threatening anaemia. Other long-term issues include strokes, kidney failure, and vision problems like retinal detachment.

Scientists have a long history of studying this condition. An American physician named James B. Herrick first described the disease in 1910. In 1949, E. A. Beet and J. V. Neel discovered how the disease is passed through genes. A major discovery occurred in 1954 regarding the relationship between genetics and malaria. Researchers found that people with a single abnormal gene, called a carrier, have some protection against malaria. This protection is likely why the sickle cell trait persists in populations where malaria is common.

The impact of sickle cell disease is global. It is estimated to affect about 7.7 million people worldwide. About 80% of all cases occur in sub-Saharan Africa. It is also found in parts of India, West Asia, and North Africa. The disease causes an estimated 34,000 direct deaths every year. It is also a contributory factor in 376,000 other deaths. Without medical care, many people do not reach adulthood. However, with modern healthcare, the median life expectancy is between 58 and 66 years.

Medical treatments have evolved significantly over time. Doctors use vaccinations, antibiotics, and folic acid to manage symptoms. Some patients receive blood transfusions or medications like hydroxycarbamide. In 2023, a major breakthrough arrived with new gene therapies. These therapies involve the genetic modification of blood-forming stem cells in the bone marrow. This allows doctors to address the root cause of the disorder at a cellular level.

This represents a new era in treating inherited blood diseases.