Types of blood disorders

Overview

Blood disorders, also referred to as blood diseases or blood conditions, include a range of conditions affecting the components and functions of blood. These disorders can significantly impact an individual's health by altering the production, quality and functioning of blood cells. Types of blood disorders include: aplastic anaemia, sickle cell disease, thalassemia, autoimmune blood disorders, myelodysplastic syndrome (MDS), and myeloproliferative disorders.

This page explains the different categories of blood disorders, including their definitions, symptoms, and treatment. We will also highlight conditions that can be helped with stem cell transplants and why more donors are needed in the long run.

Aplastic Anaemia

Aplastic anaemia is a serious but rare blood disorder in which the bone marrow doesn't make enough new blood cells. This affects red blood cells, white blood cells, and platelets, which are all important for carrying oxygen, fighting infections, and stopping bleeding.

Some people are born with inherited forms of this blood disorder, but environmental factors can trigger it, such as exposure to toxic chemicals, certain medications, or viral infections. In other instances, however, the condition develops because of unknown factors.

When aplastic anaemia occurs, stem cells in the bone marrow are damaged, causing them to stop producing more blood cells. This puts sufferers at risk of frequent infections, chronic tiredness, and uncontrollable bleeding.

Symptoms

The symptoms of aplastic anaemia vary, based on which type of blood cell is low.

• Low red blood cells: causes tiredness, weakness, dizziness, and pale skin
• Low white blood cells: leads to frequent or long-lasting infections
• Low platelets: results in easy bruising, nosebleeds, and prolonged bleeding from cuts.

Treatment

The treatment for aplastic anaemia depends on its severity. Sometimes it is mild, and your doctor may simply monitor your health with regular blood tests.

It can improve on its own, but may also worsen. You will need treatment to suppress your immune system, which can help blood counts recover in up to three out of four cases. You will also receive blood transfusions to replenish your red cells and platelets and medications to prevent infections.

If you are young and fit enough, severe aplastic anaemia is treated with a stem cell transplant using donor cells: an allogeneic transplant. This is also the first option for inherited aplastic anaemia, as immune suppression is ineffective.

Outlook

Treatment for aplastic anaemia has improved over the years, and many people respond well. Around six in 10 people live at least five years after diagnosis, and this number is higher for those with moderate forms of the disease.

For moderate aplastic anaemia, nine in 10 people can expect to live at least five years. In many cases, symptoms ease over time and less intensive treatment is needed.

Severe aplastic anaemia has a more guarded outlook, but treatment still offers good outcomes, especially for younger people. Those under 60 often respond well to immune-suppressing therapy, with nine in 10 living at least five years. Older patients may have fewer options, as stem cell transplants are usually unsuitable.

Importantly, these figures do not suggest that people only live for five years. Many people recover from this blood disorder and go on to live longer and normal lives. The five-year timeframe simply reflects how long the patients are monitored during clinical trials.

Sickle cell disease

Sickle cell disease is a common type of blood disorder that affects red blood cells. Instead of being round, they become crescent-shaped, causing a sickle cell crisis. In a sickle cell crisis, the crescent-shaped red cells block small blood vessels and slow blood flow in larger ones, causing great pain and other symptoms. There is no full understanding of what causes a sickle cell crisis, but we know they can be brought on by infection, stress, cold, dehydration and extreme exercise.

You can only inherit sickle cell disease if both your parents carry the sickle cell gene. If you inherit the gene from one parent, it is called having a sickle cell trait. You can then pass the gene on to your children, but do not have the disease yourself.

There are around 17,500 people in the UK with sickle cell disease, which is often called sickle cell anaemia or just ‘sickle cell’. This is a genetic condition present from birth. Anyone can have sickle cell disease, but it is most common in people from African and Caribbean backgrounds.

Symptoms

A sickle cell crisis is typically very painful, often causing pain in the bones, chest, or abdomen. Additional symptoms may include:

• Swollen hands and feet.
• Swelling in the abdomen (enlarged spleen)
• Tiredness and lack of energy.
• Frequent infections with a high temperature.

Sickle cell is very variable in how it affects people, and the reasons for this variability are poorly understood. Over time, sickle cell can cause complications and organ damage. People with sickle cell have a higher risk of:

• Stroke
• Blindness
• Bone damage, and
• Acute chest syndrome causes breathlessness and chest pain.

Treatment

During a crisis, painkillers and oxygen are typically required. Your doctor will also address any known crisis causes, such as providing warmth or fluids. Various drugs can help prevent crises, and regular blood transfusions may be administered to boost normal haemoglobin levels.

The only cure for sickle cell disease is a stem cell transplant using blood cells from a donor (an allogeneic transplant). This option is usually considered for children with severe, hard-to-control sickle cell disease who have a relative with closely matched bone marrow. Doctors are testing clinical trials for children without a close relative match using stem cells from unrelated donors, known as MUD (matched unrelated donor) transplants.

Outlook

The outlook for individuals with sickle cell disease has been steadily improving. Early screening of babies for this blood disorder at birth allows for prompt treatment, and new treatments are better at controlling the disease and reducing complications.

Although statistically, people with sickle cell disease do not live as long as those without the disease, life expectancy is increasing as management of the condition improves. It is important to note that these statistics reflect past treatments, and children born today are likely to have even better outcomes.

Thalassaemia: beta-thalassaemia

Thalassaemia is a type of anaemia. The condition is due to a genetic mutation which affects the bone marrow's ability to produce sufficient haemoglobin, the protein responsible for carrying oxygen in the blood.

There are two main types of thalassaemia: alpha and beta. Both are genetic conditions that affect the production of healthy red blood cells. We have only included information on beta thalassaemia here, as stem cell transplants for alpha thalassaemia are still regarded as highly experimental.

You can only inherit beta-thalassaemia if both your parents carry a beta-thalassaemia gene. If you inherit the gene from one parent, you are a carrier. You can then pass the gene on to your children, but do not have the disease yourself.

There are around 1,000 people in the UK with beta-thalassaemia. It is a genetic condition that you have from birth. Anyone can have it, but it is most common in people from the Mediterranean, the Middle East, India, Pakistan, Bangladesh and South East Asia.

Symptoms

Thalassemia symptoms vary depending on the severity of the condition. In the UK, babies are screened for thalassemia, enabling early treatment to prevent many symptoms. However, even with good management, individuals with thalassemia may be shorter than average and at risk of complications like diabetes and gland disorders due to iron overload.

Mild symptoms of beta-thalassemia minor (beta-thalassemia trait) typically cause mild anaemia, leading to fatigue, dizziness or weakness, frequent headaches and pale skin.

Beta-thalassemia major and beta-thalassemia intermedia can cause more severe symptoms, including shortness of breath with exertion, heart palpitations, jaundice, dark or tea-coloured urine, slow growth or delayed development, a swollen abdomen, and frequent infections in infants.

Treatment

If you have beta-thalassaemia, you will need blood transfusions every few weeks throughout your life. A side effect is that too much iron builds up in your body. This can cause organ damage, so you need medication to remove it. This is called chelation therapy.

With beta-thalassaemia, the spleen can become very enlarged. Your doctor may suggest a splenectomy operation to remove it. This will reduce the discomfort the enlarged spleen causes and can mean you do not need transfusions as often.

The only cure for beta-thalassaemia is a stem cell transplant using stem cells from a donor; an allogeneic transplant. The patient usually needs to have a relative whose bone marrow is a close match. Doctors are testing transplants in clinical trials using stem cells taken from unrelated donors for children who do not have a close relative who is a match. These are called MUD transplants, which stands for ‘matched unrelated donor’.

Outlook

People born with thalassaemia usually live a normal lifespan if they have the proper treatment and their conditions are appropriately managed.

Autoimmune disorders

Autoimmune disorders are not strictly blood disorders, but they are sometimes treated using stem cell transplants. These conditions occur when the immune system becomes overactive and attacks healthy tissue. A wide range of diseases fall under this category, including multiple sclerosis (MS), Crohn's disease, and rheumatoid arthritis.

Because these conditions vary widely, treatment options also differ and are not all covered here. However, stem cell transplants have been explored under the following circumstances:

• The condition is severe
• It does not respond to conventional treatment, or few effective treatments exist.
• There is a risk of severe organ damage if left untreated

The idea is that a stem cell transplant can ‘reboot’ the immune system, potentially halting or even reversing the disease. This approach has shown the most promise in cases of relapsing-remitting MS, Crohn's disease, and systemic sclerosis.

In nearly all cases, patients receive their own stem cells back following chemotherapy to eliminate the faulty immune response. This is known as an autologous transplant.

Myelodysplastic Syndrome (MDS) and Myeloproliferative Disorders

Myelodysplastic syndromes (MDS) and myeloproliferative disorders affect how blood cells develop in the bone marrow. These conditions used to be classified as blood disorders, but with greater medical understanding, they’re now more often described as cancers or precancerous conditions.

They’re complex and varied in how they affect individuals, so we've covered them in more detail on a separate page. If you’d like to explore these conditions further, you can read about MDS and myeloproliferative disorders here.

Partner with DKMS

A diagnosis of a blood cancer or blood disorder can be overwhelming, but you’re not alone. By partnering with DKMS, you can help raise awareness, grow the stem cell donor registry, and support others facing similar challenges. Whether you choose to share your story or register as a potential donor, your involvement can offer real hope to people in need of a transplant.