S,S disease (sickle cell anemia)

Newborn screening for S,S disease is done using a small amount of blood collected from your baby’s heel. To learn more about this process, visit the Blood Spot Screening page.

During screening, a special machine measures certain types of hemoglobins in your baby’s blood. Babies with different types of hemoglobins (specifically hemoglobin S) might have S,S disease.

If your baby’s blood spot screening result for S,S disease is out-of-range, your baby’s health care provider will contact you. Together, you will discuss next steps and follow-up plans.

An out-of-range screening result usually means that your baby has the condition and that your baby needs more follow-up testing. To learn more about screening results, visit the Blood Spot Screening Results page.

Your baby may need the following tests after an out-of-range screening result:

• Blood tests
• Genetic testing using a blood sample

You should complete any recommended follow-up testing as soon as possible. Babies with this condition can have serious health problems soon after birth if they are not diagnosed and treated quickly.

False-positive newborn screening results for this condition are rare. However, screening samples that are collected after a baby receives red blood cells from someone else (a red cell transfusion) will be inaccurate.

Newborn screening helps babies lead healthier lives. If your baby has an out-of-range result, follow up with your health care provider quickly. It is important to follow their instructions. Your baby may need to get treatment right away, even if they are not showing signs or symptoms. In some cases, your baby’s health care provider may decide it is best to watch (monitor) your baby to decide next steps. Careful monitoring and early treatment will help your baby stay as healthy as possible.

Many infants with S,S disease do not have signs and symptoms of the condition until later in life. In some cases, signs of the condition can appear within two months after birth. 

Many children may not have symptoms until they become very sick. It is important to see a doctor and start treatment quickly.

Signs of the condition may include the following:

• Low number of red blood cells (anemia)
• Serious infections
• Large spleen (usually found during a health care provider visit)
• Periodic episodes of pain or painful swelling in hands or feet
• Difficulty breathing

The condition is caused by a change in the HBB gene. This gene gives the body instructions for making beta-globin, a protein found in hemoglobin. 

The change in HBB creates an abnormal beta-globin called hemoglobin S (HbS). The abnormal beta-globins cause red blood cells to be sickle-shaped instead of round. Red blood cells containing mostly sickle hemoglobin can break down more quickly and can block small blood vessels.

S,S disease is a genetic condition. Babies inherit it from their biological (birth) parents. To learn more about genetic conditions, visit MedlinePlus Genetics.

• S,S disease is an autosomal recessive condition. Babies inherit the condition when each parent passes down a nonworking HBB gene to their baby. Only babies with two nonworking HBB genes—one from the mom and one from the dad—have this condition.
  • People with one normal copy and one nonworking copy of the HBB gene are said to have sickle cell trait (sometimes also called being a carrier).
  • People with sickle cell trait do not have or develop the condition. However, they may pass down a nonworking copy of the gene to their children.
  • If two parents have sickle cell trait and have a nonworking copy of the HBB gene, they have a 1 in 4 chance of having a child with S,S disease.
  • People with sickle cell trait often do not know they are carriers of a nonworking copy of the HBB gene before having a child with the condition. In most cases, families have no history of the condition until the birth of a child with S,S disease.
  • Parents who already have a child with S,S disease still have a 1 in 4 chance of having another child with S,S disease. This 1 in 4 chance stays the same for all future children.
• Genetic counselors and medical geneticists can help families learn about this condition and the chance of having children with it. Visit the National Society of Genetic Counselors to find a genetic counselor and the American College of Medical Genetics and Genomics to find a medical geneticist.