RECURRENT APHTHOUS STOMATITIS AND ORAL CANDIDIASIS DUE TO STAT1 MUTATION

Abstract

<h3>Introduction</h3> Chronic mucocutaneous candidiasis (CMC) often presents with chronic <i>Candida</i> infections of the skin, nails or mucous membranes in the absence of invasive fungal infections. Various genetic defects are associated with CMC. Here, we describe a case of recurrent aphthous stomatitis and chronic oral candidiasis due to gain-of-function (GOF) mutation in STAT1. <h3>Case Description</h3> A 21-year-old male presented to the Allergy and Immunology clinic with long-standing history of recurrent aphthous ulcers and oral candidiasis. He had previously undergone evaluation as a child with normal immunoglobulin levels, normal antibody response to vaccines and normal delayed-type hypersensitivity skin test to <i>Candida</i> antigen, but low absolute NK cells. Targeted genetic testing was negative for APECED and IPEX. He continued to experience frequent aphthous ulcers and oral thrush that can be debilitating at times, with one episode resulting in hospital admission due to severe mucosal pain and PO intolerance. Repeat immunology evaluation was similar to prior. He had low absolute NK cells, and NK cell function study using chromium release assay was notably decreased. A comprehensive primary immunodeficiency next generation sequencing panel identified a pathogenic heterozygous c.800C>T (p.A267V) mutation in STAT1. <h3>Discussion</h3> While fungal infection of the oral mucosa is a main clinical feature of CMC, aphthous stomatitis can be found frequently in patients with STAT1 GOF mutations as well. These patients also frequently have decreased NK cells and NK cell function. It is important to be aware of these additional phenotypes in the evaluation of a patient with CMC.