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Severe combined immunodeficiency (SCID): heel prick screening

Severe combined immunodeficiency (SCID) is an inherited condition. It is caused by a gene passed down from parents to their child. SCID is rare but very serious.

Babies born with SCID have a very weak immune system. Their body does not make enough T-cells. T-cells are a type of immune cell that fights infection.

Early detection and treatment is very important. Common infections can be life-threatening for babies with SCID if they do not get treatment.

Babies born in Ireland with SCID

About 1 in 40,000 babies born in Ireland has SCID.

How heel prick screening can help

Babies are checked for SCID as part of heel prick screening. They are offered this screening when they are around 5 days old.

About heel prick screening

Heel prick screening also checks for other conditions. One of these is the adenosine deaminase (ADA) deficient SCID known as ADA-SCID. ADA-SCID is a type of SCID.

A midwife or nurse will take a few drops of blood from your baby's heel using a special device.

If the heel prick test suggests that your baby might have SCID, you will be contacted and more tests will be arranged.

If these tests confirm your baby has SCID, your baby will get urgent treatment in hospital. The earlier treatment for SCID starts, the better for the baby.

Treatment for SCID can include a bone marrow transplant or gene therapy. A specialist team will support you and explain all the treatment options available.

Page last reviewed: 9 April 2026
Next review due: 9 April 2029