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DiGeorge Syndrome də-ˈjȯrj-

by James Fernandez, MD, PhD

DiGeorge syndrome is a congenital immunodeficiency disorder in which the thymus gland is absent or underdeveloped at birth.

Usually, DiGeorge syndrome is due to a chromosomal abnormality, but it does not usually run in families. Boys and girls are equally affected. The fetus does not develop normally, and abnormalities often occur in the following:

  • Heart: Children are often born with a congenital heart disorder.

  • Parathyroid gland: Children are usually born with underdeveloped or no parathyroid glands (which help regulate calcium levels in the blood). As a result, calcium levels are low, leading to muscle spasms (tetany). Spasms usually start within 48 hours after birth.

  • Face: Typically, children have unusual facial features, with low-set ears, a small jawbone that recedes, and wide-set eyes. They may have a split in the roof of the mouth (cleft palate).

  • Thymus gland: The thymus gland is necessary for the normal development of T cells. Because this gland is missing or underdeveloped, the number of T cells is low, limiting their ability to fight many infections. Infections begin soon after birth and recur often. However, how well T cells function varies considerably. Also, T cells may spontaneously start functioning better.

The prognosis usually depends on the severity of the heart disorder.

Diagnosis

Doctors suspect the diagnosis based on symptoms. Blood tests are done to determine the total number of blood cells and the number of T and B cells and to evaluate how well T cells and the parathyroid glands are functioning. Blood tests are also done to determine how well the body produces immunoglobulins in response to vaccines.

A chest x-ray may be taken to check the size of the thymus gland. Chromosomal tests may be done to look for abnormalities.

Treatment

For children who have some T cells, the immune system may function adequately without treatment. Infections that develop are treated promptly. Calcium and vitamin D supplements are given by mouth to prevent muscle spasms.

For children who have very few or no T cells, the disorder is fatal unless transplantation of thymus tissue is done. Such transplantation can cure the immunodeficiency. Before the thymus tissue is transplanted, it is placed in a culture dish and treated to eliminate mature T cells. These cells may identify the recipient’s tissue as foreign and attack it, causing graft-versus-host disease (see Graft-versus-host disease). Stem cell transplantation may also be done.

Sometimes the heart disease is worse than the immunodeficiency, and surgery to prevent severe heart failure or death may be needed.