bubble_chart Overview

Also known as DiGeorge syndrome or the third and fourth pharyngeal pouch syndrome. This condition is a congenital immunodeficiency caused by abnormal development of the first to sixth pharyngeal pouches during embryogenesis. Between the 6th to 10th week of gestation, the thymus, parathyroid glands, thyroid gland, parts of the face, aortic arches, and heart develop from the cellular components of the first to sixth pharyngeal pouches. By the 12th week of pregnancy, the thymus migrates to the thoracic region. If these embryonic tissues develop abnormally before this stage, the syndrome occurs. All cases of this syndrome are sporadic, suggesting it is not caused by genetic defects but rather by abnormalities in the embryonic environment, such as maternal alcoholism, which may be one of the contributing factors. Pathological examination reveals the absence or hypoplasia of the thymus and thyroid gland.

bubble_chart Clinical Manifestations

1. It can appear immediately after birth: ① Characteristic facial features, such as hypertelorism, micrognathia, low-set auricles, and other deformities. ② Persistent hypocalcemic convulsions that cannot be corrected by calcium supplementation alone. ③ Abnormalities of the main arteries, such as dextroposition of the aorta, tetralogy of Fallot, etc.

2. After the neonatal period, recurrent viral, fungal, or Pneumocystis carinii infections occur, or infections follow a chronic course. Severe reactions, even fatal ones, often occur in response to various live attenuated vaccines, such as smallpox, BCG, and measles vaccines. Patients with severe conditions are also prone to bacterial infections.

bubble_chart Auxiliary Examination

① Decreased lymphocytes in peripheral blood, especially reduced T cells, with an increased percentage of B cells. ② Significantly reduced cellular immune function. ③ Variable humoral immune function. Serum Ig levels are often not low. ④ Decreased blood calcium levels. ⑤ Reduced parathyroid hormone levels.

bubble_chart Treatment Measures

Most patients with complete DiGeorge syndrome die during infancy; those with incomplete forms may experience spontaneous improvement in T-cell function and have a longer survival. For hypoparathyroidism and hypocalcemia, long-term treatment with vitamin D and calcium preparations is recommended. Severe cases may benefit from fetal thymus tissue transplantation to improve immune function. In China, thymus tissue from aborted fetuses was cultured in vitro for about 14 days and used to treat three patients with immunodeficiency, achieving some therapeutic effect. Bone marrow or lymphoid tissue transplantation can also be attempted, though the outcomes are variable. Congenital cardiovascular malformations can be treated surgically.