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Nezelof syndrome is an autosomal recessive [6] congenital immunodeficiency condition due to underdevelopment of the thymus.The defect is a type of purine nucleoside phosphorylase deficiency with inactive phosphorylase, this results in an accumulation of deoxy-GTP which inhibits ribonucleotide reductase.
Thymic hypoplasia is a condition where the thymus is underdeveloped or ... There are various causes of thymic hypoplasia such as 22q11.2 deletion syndrome ...
The two most common genetic syndromes linked to thymus development defects are 22q11.2 deletion syndrome and CHARGE syndrome. Patients with these syndromes exhibit a variety of symptoms because the genes TBX1 and CHD7 , associated with these disorders, play a role in the development of the entire midline region. [ 1 ]
When the thymus tissue fails to descend appropriately or fails to involute, thymus tissue remains in various locations along this pathway. Locations that solid thymus tissue has been reported include near the thyroid (most common), within the thyroid, the base of the skull, and within the pharynx or trachea. [6] [2]
The thymus gland in normal patients will gradually decrease in size because the need for the thymus gland diminishes. The decrease in the size of the thymus gland occurs because the body already has a sufficient number of developed T-cells. [13] However, a patient with X-SCID will be born with an abnormally small thymus gland at birth. [9]
A thymoma is a tumor originating from the epithelial cells of the thymus that is considered a rare neoplasm. [1] Thymomas are frequently associated with neuromuscular disorders such as myasthenia gravis; [2] thymoma is found in 20% of patients with myasthenia gravis. [3]
In the thymus, the AIRE causes transcription of a wide selection of organ-specific genes that create proteins that are usually only expressed in peripheral tissues, creating an "immunological self-shadow" in the thymus. [10] [11] It is important that self-reactive T cells that bind strongly to self-antigen are eliminated in the thymus (via the ...
Immunodeficiency involves both deficient humoral and cellular immunity. Patients have low total serum antibodies. The thymoma may inhibit the thymus’s normal role in production of self-tolerant T lymphocytes. These T-lymphocytes then attack the B cell precursors in the marrow, preventing maturation and ultimately resulting in ...