What question did this study set out to answer?

To present a case of adult-onset STAT3 gain-of-function syndrome and its management.

January 21, 2026

STAT3 gain-of-function mutation presenting with adult-onset recurrent abdominal pain, fever and lymphadenopathy, managed by JAK inhibitor therapy

Key Points

To present a case of adult-onset STAT3 gain-of-function syndrome and its management.
Documented clinical history of abdominal pain, fever, and lymphadenopathy.
Performed imaging to assess mesenteric lymphadenopathy.
Conducted genetic analysis to determine the presence of the STAT3 mutation.
Administered targeted therapy with tofacitinib.
Confirmed a heterozygous gain-of-function mutation in the STAT3 gene.
The patient experienced significant clinical improvement post-treatment.
Imaging showed radiological improvement after targeted therapy.

Abstract

Signal transducer and activator of transcription 3 (STAT3) gain-of-function (GOF) syndrome is a rare genetic immune dysregulation disorder that typically presents in infancy with autoimmunity, lymphoproliferation, susceptibility to infections and growth delay. We report a case of a man in his late 20s admitted to hospital multiple times with abdominal pain, fever and raised C-reactive protein, where imaging revealed progressive mesenteric lymphadenopathy. A definitive diagnosis remained elusive until genetic analysis highlighted a GOF heterozygous mutation in the S TAT3 gene. Targeted therapy with Janus kinase inhibitor (tofacitinib) led to significant clinical and radiological improvement. This case underscores the value of a multidisciplinary assessment and early genome sequencing in diagnosing unexplained systemic manifestations, offering promising prospects for more effective management through targeted therapies.

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