DiGeorge syndrome (DGS) is named after Dr. Angelo DiGeorge, who first described the disease in the 1960s. Dr. DiGeorge was the first to demonstrate the role of the thymus in immune function. He described four cases in involving infants with thymic hypoplasia, hypoparathyroidism, and recurrent infection.
DiGeorge syndrome (DGS), also called DiGeorge anomaly or thymic aplasia, is an immune system disorder that occurs when the thymus gland is absent or not fully developed. Patients are born with this disorder.
The thymus gland is responsible for producing a type of white blood cell called T cells, which help the body fight against disease and infection. When the thymus gland is absent or underdeveloped, not enough T cells are produced. Therefore, patients with DGS syndrome are vulnerable to infections.
This disorder is also associated with other developmental defects, including abnormalities of the heart and large blood vessels around the heart and face. In addition, DGS patients often have hypoparathyroidism (underactive parathyroid glands), and the esophagus (the tube that leads from the mouth to the stomach) is typically underdeveloped.
Depending on how underdeveloped the parathyroid gland is, some patients may experience low calcium levels in the blood, which may lead to seizures. This is because the parathyroid gland is partially responsible for regulating the body's calcium levels.
The condition is caused by a genetic defect. DGS patients are missing a specific region on chromosome 22 that contains approximately 30-40 genes. The chromosomes contain the genetic makeup of an individual. Genetic research has identified one particular gene deletion on chromosome 22, TBX1, which is thought to be responsible for many of the features of DGS. In addition the same region of chromosome 22 also contains the COMT gene, and a deletion in this region is thought to contribute to the psychiatric complications of the disease. In a minority of cases, the defect is inherited (passed down from parents to their children). In most cases, patients are born without the gene by chance.
Researchers estimate that about one out of 3,000-4,000 individuals worldwide are born with DGS. Men and women are equally affected by DGS.
The disorder is usually diagnosed soon after birth because of the distinct physical defects and heart abnormalities associated with it.
There is currently no cure for DiGeorge syndrome (DGS). Thymus gland and bone marrow transplants have been conducted, with varying effectiveness. Patients typically receive supplements with calcium and vitamin D to manage their underactive parathyroid glands.
The prognosis varies among patients. In approximately 1% of cases, the thymus is completely missing. Some patients who have partial DGS may experience spontaneous T cell improvement and parathyroid function. However, most patients with complete DGS die within the first six months of life. Most deaths are the result of heart defects. Infections caused by severe immune deficiency are the second most common cause of death.
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