A 2-week-old girl is evaluated by a specialist because her physical appearance is abnormal.She has been hospitalized since birth.(Normal values are given in parentheses.)Her CD3 level is reported as 15% (60-80%),CD4 = 10% (30-65%),CD8 = 5% (10-40%),and CD19 = 84% (5-20%).Serum immunoglobulin levels are normal.Karyotyping reveals a deletion on chromosome 22.This girl has:

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The low percentage of CD3, CD4, and CD8, along with the high percentage of CD19, suggest a T-cell deficiency with an associated B-cell expansion, consistent with the diagnosis of DiGeorge syndrome. The deletion on chromosome 22 confirms this diagnosis, as this genetic abnormality is often associated with DiGeorge syndrome. Bruton's hypogammaglobulinemia and Wiskott-Aldrich syndrome are X-linked diseases that affect B and T cells, respectively. Ataxia telangiectasia is a rare autosomal recessive disorder characterized by neurologic symptoms and immune dysfunction, but the presentation does not match the clinical findings for this patient.

A 2-Week-Old Girl Is Evaluated by a Specialist Because Her