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Key Features

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  • Congenital heart defects

  • Hypocalcemia and seizures

  • Distinctive craniofacial features

  • Thymic hypoplasia

  • Incidence is about 1:4000 births

  • Associated immunodeficiency is secondary to the aplastic or hypoplastic thymus

  • Most patients have no or only mild immune defects

  • The term partial DiGeorge syndrome is commonly applied to patients with impaired rather than absent thymic function

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Clinical Findings

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  • Clinical characteristics include congenital heart defects, hypocalcemia due to hypoparathyroidism, distinctive craniofacial features, renal anomalies, and thymic hypoplasia

  • Presentation usually results from cardiac failure or from hypocalcemia 24–48 hours postpartum

  • Infections commonly present as recurrent ear-nose-throat infections

  • Additional important clinical issues include delayed speech, cognitive impairment, and behavioral problems

  • Risk of developing schizophrenia and autoimmune disorders in increased in these patients

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Diagnosis

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  • Laboratory evaluation typically reveals normal to decreased numbers of T lymphocytes with preserved T-lymphocyte function and normal B-lymphocyte function

  • In the rare patient with absent or dysfunctional T lymphocytes, B-lymphocyte function and antibody production may be abnormal

  • Over time, T-lymphocyte numbers normalize in the majority of patients who have low numbers of T lymphocytes at initial presentation

  • Fluorescence in situ hybridization (FISH) chromosomal analysis for the microdeletion on chromosome 22, or microarray-based comparative genomic hybridization confirms diagnosis

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Treatment

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  • Surgery may be required for cardiac defects

  • Vitamin D, calcium, or parathyroid hormone replacement to correct hypocalcemia and treat seizures may be needed

  • Transfusion products should be irradiated

  • Both thymic grafts and BMT have been used successfully in patients with absent T-lymphocyte immunity

  • T-cell numbers and function should be assessed before administration of vaccine to avoid side effects

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