A human immunodeficiency syndrome caused by mutations in CARMIL2

Area of Science:

• Immunology
• Genetics
• Cell Biology

Background:

• T-cell receptor (TCR) signaling and co-stimulation are crucial for human T-cell function.
• Defects in TCR-dependent pathways result in immunodeficiencies.

Observation:

• Four patients with EBV+ disseminated smooth muscle tumors were identified with homozygous loss-of-function mutations in the CARMIL2 (RLTPR) gene.
• These patients lacked regulatory T cells but showed no organ-specific autoimmunity.

Findings:

• CARMIL2 deficiency impairs CD28 co-signalling, affecting T-cell activation, differentiation, and function.
• Perturbed cytoskeletal organization was observed, leading to T-cell polarity and migration defects.
• Human CARMIL2-deficiency is an autosomal recessive primary immunodeficiency disorder.

Implications:

• This study identifies a novel primary immunodeficiency linked to CARMIL2 mutations.
• Findings highlight the critical role of CARMIL2 in T-cell co-signalling and cytoskeletal dynamics.
• Understanding CARMIL2 function offers insights into immune regulation and potential therapeutic targets.