Sickle Cell Disease: Symptoms, Treatment and Gene Therapy

Sickle Cell Disease: Symptoms, Treatment and Gene Therapy

Sickle cell disease is an inherited red blood cell disorder in which abnormal hemoglobin makes cells hard, sticky and sickle shaped, so they die early and block small blood vessels. It causes pain crises, anemia and infections. Standard care includes hydroxyurea, transfusions and antibiotics, and two one-time gene therapies are now approved for some patients.

This guide is for people living with sickle cell disease, parents of children who have it, and anyone who saw headlines about new gene treatments and wants to know what they really mean.

Key takeaways

  • Sickle cell disease is inherited: a child must receive an abnormal hemoglobin gene from each parent.
  • About 100,000 people in the United States have the disease, according to the CDC, and about 1 in 13 Black babies is born with sickle cell trait.
  • Hydroxyurea is the first-line oral medicine and helps reduce pain crises.
  • In December 2023 the FDA approved two gene therapies, exagamglogene autotemcel and lovotibeglogene autotemcel, for people aged 12 and older.
  • In England, NICE recommends exagamglogene autotemcel for people 12 and over with recurrent crises when a stem cell transplant is suitable but no matched related donor is available.

What is sickle cell disease?

Sickle cell disease (SCD) is a group of inherited conditions that affect hemoglobin, the protein in red blood cells that carries oxygen. In SCD, the hemoglobin is abnormal, so red cells become rigid and curved like a farm sickle instead of soft and round.

The CDC explains that these sickled cells die early, leaving a constant shortage of red blood cells (anemia), and they can get stuck in small blood vessels, blocking blood flow. That blockage causes the sudden, severe pain episodes the disease is known for.

Sickle cell trait is different. A person with the trait has inherited one sickle gene and one usual gene. They do not have the disease, but they can pass the gene on. If two people with the trait have a child, that child may inherit two sickle genes and have SCD.

The CDC estimates roughly 100,000 people in the United States have SCD. More than 90% are non-Hispanic Black and an estimated 3% to 9% are Hispanic or Latino. The disease occurs in about 1 in 365 Black births and about 1 in 16,300 Hispanic births.

What are the symptoms of sickle cell disease?

The main symptoms are pain, tiredness and frequent infections, and they usually come and go. Severity varies widely from one person to the next.

The NHS lists these common symptoms:

  • Pain in the bones, joints, muscles or chest
  • Tiredness and weakness from anemia
  • Swelling in the hands and feet
  • Breathing problems
  • More frequent infections
  • Stomach pain

Symptoms can start from about 6 months old. A sudden flare of severe symptoms is called a sickle cell crisis (also called a vaso-occlusive crisis), and it can last hours, days or weeks. The NHS names dehydration, sudden temperature changes and stress as common triggers. That is one reason activities like plunging into very cold water deserve caution; our article on whether cold water swimming is good for you covers the general risks. For stress, these practical ways to calm your nerves can help.

The CDC lists serious complications including infection, acute chest syndrome (a lung complication with chest pain, fever and breathing trouble) and stroke.

How is sickle cell disease diagnosed?

Most cases are found through newborn screening, and carriers can be identified with a simple blood test at any age.

In the UK, the NHS heel prick test checks newborns for sickle cell disease and carrier status. Pregnant people are usually offered a blood test before 10 weeks to check for sickle cell genes that could be passed on. Adults can ask their doctor for a carrier test at any time. The CDC also recommends transcranial Doppler ultrasound screening for children to identify those at higher stroke risk.

What are the standard treatments?

Standard treatment aims to prevent crises, protect against infection and stroke, and manage pain quickly. Most people use a combination of daily medicine, preventive care and a plan for flare-ups.

TreatmentWhat it doesWho it is for
Hydroxyurea (hydroxycarbamide)Oral medicine that reduces sickling and helps prevent pain crisesFirst-line option, used from about 9 months of age; not for use in pregnancy
L-glutaminePowder mixed into food or drink that may reduce pain crises and hospital staysAges 5 and up
CrizanlizumabMonthly IV infusion that helps stop blood cells blocking vesselsAges 16 and up
PenicillinDaily antibiotic to lower the risk of serious blood infectionMainly children; some adults, especially after spleen removal
Blood transfusionReplaces sickled cells with healthy donor cellsSevere anemia, acute chest syndrome, stroke prevention
Stem cell transplantReplaces bone marrow with a donor's; can cure the diseaseMostly children with serious complications and a matched donor
Gene therapyModifies your own stem cells so they make healthier hemoglobinAges 12 and up with severe disease, in specialist centers

This summary is drawn from the National Heart, Lung, and Blood Institute. NHLBI also notes that voxelotor, once used to treat SCD, was withdrawn from the market in September 2024 and is no longer available.

Infection prevention matters because people with SCD are more vulnerable. Vaccines and antibiotics are the backbone here, though eating well supports overall immune health too, as our piece on nutrient-rich foods and white blood cells explains.

For pain, NHLBI lists acetaminophen or ibuprofen for mild to moderate pain and prescription opioids for severe pain. It also names complementary approaches that may help, such as cognitive behavioral therapy, massage, yoga, and meditation.

How do the new gene therapies work, and who can get them?

The two approved gene therapies take your own blood stem cells, modify them in a lab, and return them after high-dose chemotherapy. They are one-time treatments, but the process is long and demanding.

The FDA approved both on December 8, 2023 for people aged 12 and older:

  • Exagamglogene autotemcel (exa-cel) uses CRISPR/Cas9 gene editing to switch on production of fetal hemoglobin, a form that resists sickling. In the trial, 29 of 31 evaluable patients (93.5%) went at least 12 months in a row without severe pain crises.
  • Lovotibeglogene autotemcel uses a viral vector to add a gene for a modified adult hemoglobin. In its study, 28 of 32 patients (88%) had complete resolution of pain events between 6 and 18 months after infusion. It carries a boxed warning for blood cancer, so patients need lifelong monitoring.

Here is what the process involves, step by step:

  1. Assessment at a specialist center to confirm you are eligible and fit enough.
  2. Collection of your own blood stem cells.
  3. Lab modification of those cells, which takes time.
  4. Myeloablative conditioning: high-dose chemotherapy that clears your bone marrow so the modified cells can take its place.
  5. A single infusion of your modified cells.
  6. Weeks in hospital while the new cells settle in, then long-term follow-up.

Side effects reported to the FDA include low blood counts, mouth sores, nausea, fever with low white cells and pain. The conditioning chemotherapy carries its own risks, so these therapies are not a casual choice.

In England, the headlines about a "life-changing treatment on the NHS" refer to exa-cel. NICE approved it under a managed access scheme. The NICE recommendation covers people 12 and over with recurrent vaso-occlusive crises and certain genotypes, when a stem cell transplant is suitable but no matched related donor is available, and only for those who have had at least 2 crises per year in each of the previous 2 years. More data will be collected before NICE reviews it again. Headlines often blur these details, so it helps to know how to spot misleading health news.

Living well with sickle cell disease

Day-to-day habits can lower the chance of a crisis. The CDC recommends drinking enough fluids, avoiding extreme temperatures and keeping up with vaccines.

A simple daily checklist built on that advice:

  • Drink water steadily through the day, more in hot weather or during exercise.
  • Dress for the weather and avoid sudden temperature changes.
  • Take hydroxyurea or other prescribed medicines every day, even when you feel well.
  • Keep vaccinations and any daily antibiotics up to date.
  • Rest well; fatigue is common, and these sleep hygiene tips can help.
  • Carry a written care plan for emergencies.

Living with a lifelong condition also takes an emotional toll. Our guide to protecting your emotional wellness offers a starting point.

Common mistakes and misunderstandings

  • Thinking gene therapy is available to everyone. It's limited to people 12 and over with severe disease who meet specific criteria.
  • Confusing trait with disease. Carriers usually have no symptoms but can pass the gene to their children.
  • Stopping hydroxyurea when you feel well. It works by preventing crises, so gaps reduce its benefit.
  • Waiting out a fever at home. A high temperature in someone with SCD can signal a serious infection.

When to see a doctor

Treat these as emergencies. The NHS advises calling emergency services, and not driving yourself, if you or your child with SCD has:

  • A crisis with severe pain that home treatment does not control
  • Breathing difficulties or chest pain
  • Repeated vomiting
  • A high temperature
  • A painful erection that will not go away (priapism)

Also seek urgent care for signs of stroke, such as sudden weakness, trouble speaking or a severe headache. See your doctor or sickle cell team soon if crises are becoming more frequent, you feel increasingly tired or short of breath, or you want to discuss whether gene therapy or a transplant might suit you.

Frequently asked questions

Is sickle cell disease curable?

For some people, yes. A stem cell transplant from a matched donor can cure it, and NHLBI reports about 90% success in children with a matched related donor. Gene therapies are designed as one-time treatments that can end severe crises for many patients. Both options carry serious risks, so most people still rely on long-term standard care.

Who qualifies for gene therapy?

In the US, both approved therapies are for people 12 and older with sickle cell disease. In England, NICE recommends exa-cel for people 12 and over who have had at least 2 vaso-occlusive crises a year in each of the previous 2 years, when a transplant is suitable but no matched related donor is available. A specialist team decides individually.

Can sickle cell trait cause problems?

Most people with sickle cell trait live without symptoms and don't have the disease. The main practical concern is family planning, because two carriers have a chance of having a child with SCD in each pregnancy. A simple blood test can tell you whether you carry the trait, and genetic counseling can explain the odds.

What triggers a sickle cell crisis?

The NHS names dehydration, sudden temperature changes and stress as common triggers. Avoiding triggers helps, but crises can still happen, which is why preventive medicine, steady fluids and a clear pain plan matter even on good days.

What to do next

  1. If you don't know your carrier status, ask your doctor for a sickle cell blood test.
  2. Write a crisis plan with your care team, including which pain medicines to use and when to go to hospital.
  3. Ask your specialist whether hydroxyurea, transfusions or gene therapy fit your situation.
  4. Keep vaccines and any prescribed antibiotics current.

This article is for general information and is not medical advice.

Sources

Last reviewed: October 2026.

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