Knowra DiGeorge syndrome DiGeorge syndrome DiGeorge syndrome is a congenital disorder most often caused by a deletion at chromosome 22q11.2. Its variable features can include heart defects, immune deficiency, palate abnormalities, and low blood calcium.
22q11.2 deletion syndrome : A genetic condition caused by loss of a small region of chromosome 22, with a wide range of possible features. DiGeorge syndrome is one name used within this broader condition, which also includes other clinical presentations.
Fluorescence in situ hybridization : A laboratory method that uses fluorescent DNA probes to detect selected chromosome sequences. It can detect the common 22q11.2 deletion, though some smaller or atypical deletions may be missed.
CATCH-22 : A mnemonic for features associated with 22q11.2 deletion: cardiac defects, abnormal facies, thymic hypoplasia, cleft palate, and hypocalcemia. It summarizes findings often linked to DiGeorge syndrome but cannot capture the full range of presentations.
T-cell deficiency : A shortage or impaired function of T lymphocytes, which coordinate cellular immune responses. Its severity ranges from mild immune abnormalities to profound deficiency when thymic development is severely impaired.
Pharyngeal arches : Embryonic tissue structures that contribute to the development of the face, neck, and several organs. Abnormal development of pharyngeal structures helps explain the syndrome’s palate, heart, and thymus findings.
Chromosomal microarray : A genetic test that surveys the genome for gains and losses of DNA segments. It can identify the 22q11.2 deletion and define its extent.
Velocardiofacial syndrome : A historical clinical name for a condition often caused by a 22q11.2 deletion, associated with palate, heart, and facial features. This overlapping label emphasizes facial and palate findings rather than thymic and calcium abnormalities.
Hypocalcemia : An abnormally low concentration of calcium in the blood. It may cause seizures or muscle spasms, particularly around birth or during illness.
Thymus : A lymphoid organ where T cells mature, especially during childhood. Underdevelopment of the thymus can impair T-cell development and weaken cellular immunity.
Echocardiography : An ultrasound examination that shows the heart’s structure and function. It evaluates suspected congenital heart defects, including lesions involving the aortic arch or outflow tract.
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