Differentials

22q11.2 Microdeletion Syndrome/DiGeorge syndrome

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

Abnormal development of the 3rd and 4th pharyngeal pouches, which include the thymus.

Spectrum of immune dysregulation varies, although the most severe form results in an absence of T cells.

Associated defects include palatal abnormalities, distinct facies, hypoparathyroidism, and cardiac defects.[34]

INVESTIGATIONS

Confirmation requires deletion of 22q11.2 by fluorescence in situ hybridization, DNA microarray, or genetic testing.[44][45]

DiGeorge syndrome

Omenn syndrome

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

Results from hypomorphic variants in genes associated with SCID.[34]

Differentiating symptoms include eosinophilia, splenomegaly, and lymphadenopathy.

INVESTIGATIONS

Flow cytometry generally demonstrates increased CD4+CD45RO+ T cells (memory T cells) and markedly decreased CD4+CD45RA+ T cells (naive T cells).

Molecular diagnosis is used to identify mutations in genes associated with this disorder, such as recombination activating genes (RAG1 and RAG2), Artemis/DNA cross-link repair 1C (DCLRE1C), and others.

Zeta chain-associated protein 70 deficiency

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

May or may not present with recurrent infection.

Some patients have been described with palpable lymphadenopathy and normal thymic shadow.[34]

INVESTIGATIONS

Flow cytometry shows decreased CD8+ T cells with normal B cells and normal natural killer cells.[34]

HIV-1

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

Maternal history of HIV-1 infection.

Clinical phenotype may be identical to SCID.

INVESTIGATIONS

HIV polymerase chain reaction confirms diagnosis.

HIV infection

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