This patient presents with IPEX (immunodysregulation polyendocrinopathy enteropathy X-linked) which is a mutation of the FOXP3 gene which is a regulator for the Regulatory T cell lineage. It leads to the dysfunction of regulatory T-cells and the subsequent autoimunity.

So I didn't remember IPEX but I do know some basic inmuno and the stem sounded like many autoinmune manifestations, so logically a decrease in Treg lymphocytes (which are inmunosuppresive) seemed like the best answer.

IPEX: FOXP3 deficiency --> Regulatory T cell dysfunc --> autoimmunity

• Enteropathy(diarrhea)

• Endocrinopathy

• Nail dystrophy

• dermatitis (eczematous)

• +/- other autoimmune conditions

• associated with diabetes in male infants

Page 102 in FA19

Regulatory T cells Help maintain specific immune tolerance by suppressing CD4 + and CD8 + T-cell effector functions. Identified by expression of CD3, CD4, CD25, and FOXP3.

Activated regulatory T cells (Tregs) produce anti-inflammatory cytokines (eg, IL-10, TGF-β).

IPEX (Immune dysregulation, Polyendocrinopathy, Enteropathy, X-linked) syndrome— genetic deficiency of FOXP3 = autoimmunity. Characterized by enteropathy, endocrinopathy, nail dystrophy, dermatitis, and/or other autoimmune dermatologic conditions. Associated with diabetes in male infants.