Sickle cell disease (SCD) is the most common inherited blood disorder in the United States, and it affects African Americans far more than any other group. The reason is ancestry: the sickle cell gene became common in parts of Africa where malaria was widespread, because carrying one copy offers some protection against severe malaria. Today, SCD in the African American population is identified at birth through newborn screening and managed with a growing set of treatments, including potentially curative options.
In this guide I explain where the disease comes from, how it shows up, how it is diagnosed and treated, and what families can do to stay ahead of complications.
What Is Sickle Cell Disease?
Sickle cell disease is an inherited disorder in which the body makes an abnormal form of hemoglobin called hemoglobin S (HbS). Hemoglobin is the oxygen-carrying protein inside red blood cells. When HbS gives up its oxygen, the molecules stick together into long chains that bend the cell into a stiff crescent, or “sickle,” shape.
Healthy red cells are soft and flexible and live about 120 days. Sickled cells are rigid, clog small blood vessels, and break down after roughly 10 to 20 days. This combination of blocked blood flow and early red cell destruction explains most of the problems people with SCD face.
SCD is a family of conditions rather than a single disease. The main types are shown below.
| Type | Genes inherited | Typical severity |
|---|---|---|
| HbSS (sickle cell anemia) | Two sickle genes | Usually the most severe |
| HbSC | One sickle gene, one hemoglobin C gene | Often milder, but eye and bone problems are common |
| HbS beta-zero thalassemia | One sickle gene, one beta-zero thalassemia gene | Similar to HbSS |
| HbS beta-plus thalassemia | One sickle gene, one beta-plus thalassemia gene | Usually milder |
| Sickle cell trait (HbAS) | One sickle gene, one normal gene | Not a disease; usually no symptoms |
Why It Is More Common in African Americans
Sickle cell disease is caused by a single-letter change in the HBB gene on chromosome 11. That change swaps the amino acid valine for glutamic acid at the sixth position of the beta-globin chain, which is what makes hemoglobin S.
In regions of sub-Saharan Africa where malaria was common for thousands of years, people carrying one sickle gene, known as sickle cell trait, were more likely to survive severe malaria and have children. Over generations, the gene became common in those populations. Many African Americans trace their ancestry to these regions, so the gene is far more frequent in this community than in the general US population.
SCD is autosomal recessive: a child must inherit an abnormal beta-globin gene from each parent. When both parents carry sickle cell trait, each pregnancy has:
- A 1 in 4 chance of a child with sickle cell disease
- A 1 in 2 chance of a child with sickle cell trait
- A 1 in 4 chance of a child with neither
Many carriers do not know their status, which is why testing before or during pregnancy is so valuable. It is also worth remembering that SCD is not limited to one group; it also occurs in people with Hispanic, Middle Eastern, Mediterranean, and South Asian ancestry.
Symptoms and Complications
Symptoms usually appear in the first year of life, once protective fetal hemoglobin falls. The hallmark is the vaso-occlusive crisis, a sudden episode of severe pain caused by sickled cells blocking blood flow to bones, joints, or organs.
Common features include:
- Recurrent pain episodes, often in the back, chest, arms, and legs
- Fatigue and pallor from chronic hemolytic anemia
- Painful swelling of the hands and feet in young children (dactylitis)
- Yellowing of the eyes (jaundice) and gallstones from red cell breakdown
- Frequent or severe infections, because the spleen stops working early in life
- Delayed growth and puberty
Serious complications include acute chest syndrome (a pneumonia-like lung injury), stroke, splenic sequestration in young children, kidney damage, eye disease, leg ulcers, priapism, and avascular necrosis of the hip. Many of these are preventable or treatable when caught early, which is the whole point of regular specialist care.
Diagnosis and Newborn Screening
Every US state screens newborns for sickle cell disease, so most African American children with SCD are identified in the first weeks of life. Early diagnosis of sickle cell disease allows families to start preventive penicillin, vaccinations, and education before the first crisis.
Confirmatory testing uses hemoglobin electrophoresis or high-performance liquid chromatography (HPLC), which measure the types of hemoglobin present. DNA testing of the HBB gene is used when results are unclear or for prenatal diagnosis.
Ongoing monitoring includes a complete blood count and reticulocyte count, which show the degree of anemia and how hard the bone marrow is working to replace lost cells. Children with HbSS or HbS beta-zero thalassemia should have yearly transcranial Doppler ultrasound between ages 2 and 16 to identify stroke risk.
Treatment and Management
Good SCD care combines prevention, prompt treatment of acute events, and disease-modifying therapy. The main options are summarized here.
| Treatment | What it does |
|---|---|
| Hydroxyurea | Raises fetal hemoglobin; reduces pain crises, acute chest syndrome, and transfusion needs |
| L-glutamine | Oral powder that reduces oxidative stress in red cells and lowers crisis frequency |
| Crizanlizumab | Monthly infusion that reduces cell stickiness and pain crises |
| Blood transfusion | Treats severe anemia and prevents stroke in high-risk children |
| Stem cell transplant | Potentially curative; best results with a matched sibling donor |
| Gene therapy | Uses the patient’s own modified stem cells; potentially curative for selected patients |
Hydroxyurea is the cornerstone and is recommended for children with HbSS from around 9 months of age. Pain crises are treated with fluids and prompt, adequate pain relief, often including opioids. In 2023, US regulators approved the first gene therapies for SCD, including a CRISPR-based treatment, marking a real turning point for eligible patients.
Health Equity and Access to Care
Because SCD predominantly affects a minority community, patients have historically faced gaps in research funding, specialist access, and emergency pain care. Many adults report long waits for pain treatment or being doubted about their pain.
In my practice, the families who do best are connected to a comprehensive sickle cell center, carry a written pain plan for emergency visits, and move smoothly from pediatric to adult care. That transition in the late teens and early twenties is a vulnerable time, and planning for it early makes a difference.
When to See a Doctor
Seek emergency care right away for anyone with sickle cell disease who has:
- A fever of 38.5°C (101.3°F) or higher
- Chest pain, cough, or trouble breathing
- Sudden weakness, numbness, facial droop, confusion, or trouble speaking
- A suddenly enlarged spleen, pale skin, or unusual sleepiness in a child
- Pain that does not respond to home treatment
- An erection lasting more than 4 hours
Frequently Asked Questions
Why does sickle cell disease mostly affect African Americans?
The sickle gene became common in African regions where malaria was widespread, because carriers were protected against severe malaria. Many African Americans descend from these populations, so the gene is more frequent. The disease also affects people of other ancestries.
Can two people with sickle cell trait have a healthy child?
Yes. Each pregnancy has a 3 in 4 chance of a child without the disease, though half of children will carry the trait. Genetic counseling can explain options, including prenatal testing.
Is sickle cell disease curable?
Stem cell transplant and the newer gene therapies can cure the disease for some patients. They carry significant risks and are not suitable for everyone, so most people are managed with long-term treatments such as hydroxyurea.
How can I find out if I carry sickle cell trait?
A simple blood test, usually hemoglobin electrophoresis or HPLC, shows whether you carry the trait. If you were born in the US, your newborn screening result may already contain this information.
