Pathophysiology
1) cellular immune deficiency in setting of absent or hypoplastic thymus and parathyroids and truncal heart defects (tetralogy of Fallot, truncus arteriosus) 2) results from defects of the third and fourth branchial arches 3) marked T cell defects
Signs and Symptoms
1) moderate retardation 2) severe cardiac defects 3) hypertelorism 4) low-set ears 5) cleft palate 6) bifid uvula 7) micrognathia 8) mucocutaneous candidiasis
Characteristic Test Findings
Laboratory – hypocalcemia
Associated Conditions
1) severe infections 2) seizures
Biochemistry
1) reduced levels of T cell and T cell functioning 2) although the number of B cells is normal, there is reduced functioning of some immunoglobulins
Inheritance/Epidemiology
1) occurs in 1/4000 births 2) defect is microdeletion at 22q11 3) most cases are sporadic 4) death usually occurs in childhood from severe infection 5) syndrome shows variable penetrance; if a small thymus is present in the neck or at the base of the tongue, then clinical presentation is less severe
Treament
supportive for infections
Tips for USMLE
catch-22 – acronym for cardiac defect, abnormal facies, T cell deficiency, cleft palate, hypocalcemia, chromosome 22 defect
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