Texas Health and Human Services / Texas Health Steps

Sickle Cell Overview

Sickle cell disease is a lifelong illness. . . Most people who have sickle cell disease should see their provider every 3 to 12 months, depending on their age.

National Heart, Lung, and Blood Institute, 2022

Sickle cell disease is the most common inherited blood disorder in the United States (American Academy of Pediatrics, 2023). About 2,000 U.S. babies are born with sickle cell disease every year (Ibid.).

“Children with sickle cell disease experience episodes of severe pain and ongoing medical challenges” (Ibid.). However, “early and ongoing medical care can minimize complications and help children with the disorder lead full and active lives.”

Sickle cell disease comprises a group of related disorders that affect an individual's red blood cells. It is caused by a change in the genes that make hemoglobin, the protein in red blood cells that carries oxygen. Sickle cell disease can cause an individual’s red blood cells to become hard, sticky and curved like a farm tool called a sickle. The misshapen red blood cells, known as sickled cells, and other anomalies can block blood flow through the body, causing recurring pain episodes or intense pain crises.

Parts of the body that don’t receive normal blood flow may eventually become damaged. Complications can include anemia, vision loss, chronic pain, deep vein thrombosis, infection, pulmonary embolism, and nerve and organ damage.

Below left, healthy red blood cells have a round, donut shape. At right, bent, sickle-shaped red blood cells.

illustration of healthy and unhealthy red blood cells

Treatment for sickle cell disease may include medications such as daily hydroxyurea, blood transfusions, gene therapy or a stem cell transplant.

Early Signs and Symptoms of Sickle Cell

Most newborns with the disease have no symptoms until age 5 or 6 months (NHLBI, 2022). Symptoms can vary and change over time. Almost all individuals with sickle cell disease experience complications during their lifetime. Some may have occasional symptoms while others have symptoms very often.

Early symptoms include:

  • Jaundice
  • Fatigue or fussiness
  • Painful swelling of hands and feet

Prevalence of Sickle Cell

Sickle cell disease “is particularly common among those whose ancestors came from sub-Saharan Africa; Spanish-speaking regions in the Western Hemisphere (South America, the Caribbean, and Central America); Saudi Arabia; India; and Mediterranean countries such as Turkey, Greece, and Italy” (Centers for Disease Control and Prevention [CDC], 2022).

In Texas, sickle cell disease affects about one of every 2,000 newborns, or 180–200 babies each year. The disease affects female and male babies equally. Texas Department of State Health Services (DSHS) data show Texas cases are most common among Black families, who account for 85 percent of cases; followed by Hispanics, who represent 5 percent of cases; and other ethnicities combined, at 10 percent.

Texas screens all newborns, regardless of ethnicity, for sickle cell disease through the DSHS Newborn Screening Program.

Sickle Cell Disease versus Sickle Cell Trait

Sickle cell disease occurs in several forms. Sickle cell anemia (HbSS) is the most common form of the disease, and usually the most severe. Individuals with sickle cell disease inherit a hemoglobin gene with the sickle mutation, called hemoglobin S or HbS, from each parent.

Sickle cell trait (HbAS) occurs when a child inherits a hemoglobin gene with the sickle variant from one parent and one normal functioning hemoglobin gene from the other parent. Sickle cell trait is NOT sickle cell disease and sickle cell trait will never turn into sickle cell disease as a child ages. It is a benign-carrier condition. However, individuals with sickle trait may be at risk for complications under extreme stress. It is considered a risk factor for complications such as hematuria or spleen swelling at high elevations. A very rare cancer, renal medullary carcinoma, occurs almost exclusively in individuals with sickle cell trait and predominately affects adolescents and young adults.

On rare occasions during intense physical activity, people with sickle cell trait may experience severe medical problems. Most people with sickle cell trait lead completely normal lives.

Forms of Sickle Cell Disease

Different forms of sickle cell disease are caused by a hemoglobin S pathogenic variant.

The individual’s genotype may be hemoglobin SS or a single copy of the S hemoglobin variant in combination with other hemoglobin variants (C, D, E or others), or with a beta thalassemia variant in the other allele. The most common types of sickle cell disease are:

  1. Sickle cell anemia hemoglobin SS
  2. Sickle-hemoglobin C disease (SC) or Sickle-C disease
  3. Sickle cell-beta thalassemia +/0 (hemoglobin S beta thalassemia +/0)
    • There are two types of sickle cell-beta thalassemia:
      1. Beta-plus (or beta+) thalassemia occurs when the beta thalassemia variant results in some hemoglobin A production.
      2. Beta-zero (or beta0) thalassemia occurs when the beta thalassemia variant does not produce any hemoglobin A.

Heredity and Sickle Cell Disease and Trait

When one partner in a couple that plans to have children is known to have sickle cell trait, the other should be screened by hemoglobin electrophoresis to determine the couple’s risk of having a child with one of the significant hemoglobinopathies.

The inheritance of hemoglobin type is autosomal recessive, with five possible combinations.

Infographics from the CDC, n.d.







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