Secretory Diarrhea Caused by Activating GUCY2C Mutation in a Patient With Atypical Kawasaki Disease: A Rare Case...

A 3-year-old male patient with recurrent hospitalizations due to diarrhea, fever, vomiting, and seizures was discovered to have a GUCY2C gene mutation, inherited from his asymptomatic father. Despite antibiotics and supportive therapy, the patient continued to suffer from persistent secretory diarrhea, recurrent febrile seizures, and features of atypical Kawasaki disease. This case describes a rare presentation of early onset diarrhea and systemic inflammation associated with a gain-of-function mutation. The GUCY2C mutations are known to dysregulate intestinal fluid homeostasis, through excessive CFTR-mediated chloride secretion causing recurrent diarrhea. Additionally, this case suggests a potential link between gut barrier dysfunction and systemic inflammation, contributing to recurrent febrile episodes and KD-like manifestations. Standard antidiarrheal therapy was ineffective, highlighting potential roles for CFTR inhibitors and immune modulation. This case highlights the interplay between genetic mutations, gastrointestinal dysfunction, and systemic inflammation, underscoring the importance of a multidisciplinary approach in managing rare genetic enteropathies with immune involvement.