PurposeHeterozygous missense STAT1 mutations leading to a gain of function (GOF) are the most frequent genetic cause of chronic mucocutaneous candidiasis (CMC). We describe the case of a patient presenting a new GOF mutation of STAT1 with the clinical symptoms of CMC, recurrent pneumonia, and persistent central erythema with papulopustules with ocular involvement related to rosacea-like demodicosis.MethodsGenetic analysis via targeted next-generation sequencing (NGS; NGS panel DIPAI v.1) exploring the 98 genes most frequently involved in primary immunodeficiencies, including STAT1, was performed to identify an underlying genetic defect.ResultsNGS identified a novel variant of STAT1, c.884C>A (exon 10), p.T295Y, not previously described. This variant was found to be gain of function using an in vitro luciferase reporter assay. Rosacea-like demodicosis was confirmed by substantial Demodex proliferation observed via the microscopic examination of a cutaneous sample. A review of literature retrieved 20 other cases of STAT1 GOF mutations associated with early-onset rosacea-like demodicosis, most with ocular involvement.ConclusionWe describe a new STAT1 GOF mutation associated with a phenotype of CMC and rosacea-like demodicosis. Rosacea-like demodicosis appears as a novel and important clinical phenotype among patients with STAT1 GOF mutation.

The significance of low leukocyte counts in cerebrospinal fluid (CSF) remains unclear. We performed a 2-year retrospective study to examine microbiological outcomes associated with CSF leukocytes at 6–10/mm3. Of the 178 samples examined, we detected positive results for 11 samples, including 5 cases of tick-borne encephalitis virus infection.