PATH - T-cell disorders

Question 1

Thymic aplasia

DiGeorge syndrome

Answer 1

*22q11 deletion

failure to develop *3rd and 4th *pharyngeal pouches–>absent thymus and parathyroids

Tetany (hypocalcemia),
recurrent viral/fungal
infections (T-cell deficiency),
conotruncal abnormalities
(eg, tetralogy of Fallot,
truncus arteriosus)

*DEC T cells

• DEC PTH
• DEC Ca2+

Absent thymic shadow on
CXR

22q11 deletion detected by
*FISH

Question 2

IL-12 receptor deficiency

Answer 2

Autosomal recessive

DEC *Th1 response

Disseminated mycobacterial
and fungal infections

may present after administration of *BCG vaccine

*DEC IFN-γ.

Question 3

Autosomal dominant
hyper-IgE syndrome
(Job syndrome)

Answer 3

Deficiency of *Th17 cells due to *STAT3 mutation–>impaired recruitment of neutrophils to sites of infection

FATED: 
coarse Facies, cold (noninflamed) staphylococcal
Abscesses, retained primary
Teeth, INC IgE, Dermatologic
problems (eczema)

*INC IgE
*DEC IFN-γ

Question 4

Chronic mucocutaneous

candidiasis

Answer 4

*T-cell dysfunction

Noninvasive *Candida albicans infections of skin and mucous membranes

Absent in vitro T-cell
proliferation in response to
Candida antigens.

Absent cutaneous reaction to Candida antigens.