Severe allergic dysregulation due to a gain of function mutation in the transcription factor STAT6.

Background: Inborn errors of immunity have been implicated in causing immune dysregulation, including allergic diseases. STAT6 is a key regulator of allergic responses.
Objectives: This study sought to characterize a novel gain-of-function STAT6 mutation identified in a child with severe allergic manifestations.
Methods: Whole-exome and targeted gene sequencing, lymphocyte characterization, and molecular and functional analyses of mutated STAT6 were performed.
Results: This study reports a child with a missense mutation in the DNA binding domain of STAT6 (c.1114G>A, p.E372K) who presented with severe atopic dermatitis, eosinophilia, and elevated IgE. Naive lymphocytes from the affected patient displayed increased T _H 2- and suppressed T _H 1- and T _H 17-cell responses. The mutation augmented both basal and cytokine-induced STAT6 phosphorylation without affecting dephosphorylation kinetics. Treatment with the Janus kinase 1/2 inhibitor ruxolitinib reversed STAT6 hyperresponsiveness to IL-4, normalized T _H 1 and T _H 17 cells, suppressed the eosinophilia, and improved the patient's atopic dermatitis.
Conclusions: This study identified a novel inborn error of immunity due to a STAT6 gain-of-function mutation that gave rise to severe allergic dysregulation. Janus kinase inhibitor therapy could represent an effective targeted treatment for this disorder.
(Copyright © 2023 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)