Which subset of T cells is significantly decreased or absent in IPEX?

IPEX, or Immune Dysregulation, Polyendocrinopathy, Enteropathy, X-linked syndrome, is a rare genetic disorder caused by mutations in the FOXP3 gene, which is crucial for the development and function of regulatory T cells (Tregs). Tregs, characterized by markers such as CD4+, CD25+, and FoxP3+, play a key role in maintaining immune tolerance and preventing autoimmune reactions.

In individuals with IPEX, the defective FOXP3 gene leads to a significant decrease or absence of these Tregs. As a result, the body is unable to adequately regulate immune responses, leading to widespread autoimmunity and inflammation. This is why the first option, which describes the subset of T cells that include CD4+, CD25+, FoxP3+, and T-regulatory cells, is the correct answer. The absence of functional Tregs in IPEX is central to the pathology of the condition, further emphasizing their importance in immune regulation.

In contrast, the other options do not specifically highlight a subset of T cells involved in the pathogenesis of IPEX. CD8+ T cells, CD4+ T effector cells, and CD19+ B cells may be affected in the context of autoimmune responses or