DiGeorge syndrome (DGS) is a primary immunodeficiency disease (PIDD) associated with susceptibility to infections due to decreased T cell production and function due to an absent or poorly developed thymus. The thymus is the “school house” where T-cells are educated to fight infection and prevent autoimmunity. DGS is caused by abnormal cell and tissue development during fetal growth. In addition to possible immune system problems, this abnormal development can result in altered facial characteristics, abnormal gland development (parathyroid or thyroid) or heart defects. DGS is a lifelong condition that is typically diagnosed in infancy or early childhood. Children with DGS differ in the organs and tissues affected, as well as in the severity of the disease.
The presentation of DGS varies. At one end of the spectrum is “Complete DGS” that is associated with total absence of the thymus and a severe deficiency in T-cells that requires thymic transplantation for survival. “Partial DGS” is associated with low, but not absent T-cell function and often improves during childhood. Still, approximately one-third of affected adults will have mild recurrent infections.
Most cases result from a deletion of chromosome 22q11.2 (the DGS chromosome region). A small number of cases of DGS have defects in another chromosome, notably 10p13. Infants with CHARGE syndrome (CHD7 gene) and infants of diabetic mothers also may present with DGS.
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Certain facial features are often seen with DGS - low set ears, underdeveloped chin, a short philtrum (the vertical groove on the upper lip), a bulbous nose tip, heavy eyelids and/or a small mouth.
Nasal-sounding speech can occur when a cleft palate is involved. Short stature, learning difficulties or certain psychiatric disorders are also common.
Based on which organs are affected by the syndrome, other symptoms may include:
- Frequent infections
- Low calcium levels
- Heart defects
DGS is often diagnosed at birth or in infancy based on clinical observation of multiple symptoms with various organs. A genetic test is used to confirm the diagnosis.
As the organs and tissues involved and the severity of the abnormalities vary, treatment plans for DGS must be personalized.
For instance, mild T cell problems can often be managed with antibiotics and close follow-up. On the other extreme, cases of DGS in which T cell development is severely affected have been successfully treated with bone marrow or thymus transplant.
Severe problems involving the heart or facial features may require corrective surgery.
Children with DGS benefit from a multi-specialty approach to treatment, since this disease can be associated with a spectrum of disorders that fall under varying different medical specialties including ENT, immunology, cardiology, genetics and speech therapy.
To learn more about PIDDs visit the Immune Deficiency Foundation website.