A rare mutation causing autosomal dominant STAT1 deficiency in a South African multiplex kindred with disseminated BCG infection.

BACKGROUND: Autosomal dominant signal transducer and activator of transcription 1 (STAT1) deficiency, part of the Mendelian susceptibility to mycobacterial disease (MSMD) group, frequently causes disseminated Bacillus Calmette-Guérin (BCG) infections, but has not been reported from Sub-Saharan Africa (SSA) where routine birth BCG vaccination is practiced. CASE PRESENTATION: Two half-siblings presented five years apart, with multifocal osteomyelitis as the dominant feature of disseminated BCG, which was successfully treated with antimycobacterial therapy. Whole exome sequencing demonstrated a novel heterozygous substitution in the splice site between intron 13 and exon 14 of the STAT1 gene, NM_007315: c.1128-1G>A, in the proband and his mother and was later confirmed in his half-brother. CONCLUSIONS: Children with BCG vaccine complications in SSA should be referred for further investigation and particular consideration of MSMD.

Two novel STAT1 mutations cause Mendelian susceptibility to mycobacterial disease.

Mendelian susceptibility to mycobacterial disease (MSMD) is a rare monogenetic disease, which is characterized by susceptibility to some weakly virulent mycobacteria. Here, we explored the pathogenic genes and molecular mechanisms of MSMD patients. We recruited three patients diagnosed with MSMD from two families. Two novel mutations (c.1228A > G, p.K410E and c.2071A > G, p.M691V) in STAT1 gene were identified from two families. The translocation of K410E mutant STAT1 protein into nucleus was not affected. The binding ability between gamma-activating sequence (GAS) and K410E mutant STAT1 protein was significantly reduced, which will reduce the interaction between STAT1 protein with the promoters of target genes. The M691V mutant STAT1 protein cannot translocate into the nucleus after IFN-γ stimulation, which will affect the STAT1 protein form gamma-activating factors (GAF) and bind the GAS in the promoter region of downstream target genes. Taken together, our results showed that the mutation of K410E led to impaired binding of STAT1 to target DNA, and the mutation of M691V prevented the transport of STAT1 into the nucleus, which led to MSMD. Together, we identified two novel mutations (c.1228A > G, p.K410E and c.2071A > G, p.M691V) in STAT1 gene in MSMD patients, and deciphered the molecular mechanism of MSMD caused by STAT1 mutations.

Multiple Lytic Bone Lesions Mimicking Langerhans Cell Histiocytosis: A Case of Infantile Mendelian Susceptibility to Mycobacterial Disease due to STAT1 Deficiency.

We present the first infantile disseminated Bacillus Calmette-Guérin (BCG) disease case with STAT1 deficiency, which is manifested by multiple Langerhans cell histiocytosis-like osteolytic lesions. The diagnosis of BCG-induced osteomyelitis was not initially considered until the additional biopsy revealing granulomatous inflammation, a key pathological diagnostic component for mycobacterial infection.

Autosomal dominant chronic mucocutaneous candidiasis with STAT1 mutation can be associated with chronic active hepatitis: A case report.

Background: Chronic mucocutaneous candidiasis (CMC) is a heterogeneous primary immunodeficiency disease characterized by chronic or recurrent Candida infections of the skin, nails, and mucosa and is mostly associated with STAT1 gain-of-function (GOF) mutation (GOF-STAT1 mutation). Case presentation: A two-year-old girl was presented with recurrent liver dysfunction, oral candidiasis, acute bronchial pneumonia, and cytomegalovirus infection. Even after a series of treatments, including antifungal voriconazole, nystatin treatment for oral Candida, antibiotics against bacterial infection, and bicyclol to protect the liver, the child still exhibited signs of splenomegaly. Although we performed relevant etiological tests on the child and conducted histopathology and electron microscopic examination of the liver, we could not explain the clinical symptoms. So, a genetic test was conducted to clarify the diagnosis. Since the child suffered recurrent fungal infections, we speculated that she had combined immunodeficiency. Therefore we performed high-precision clinical display PLUS detection and found that the transcription factor STAT1 had a heterozygous GOF mutation (p. R274W) in its coiled-coil domain. Conclusion: The clinical manifestations of chronic mucocutaneous candidiasis caused by GOF-STAT1 mutations are complex and range from mild local fungal infections to severe systemic diseases and are sometimes fatal. Clinicians need to be aware of the possibility of this disease in children with recurrent fungal infections for early diagnosis and treatment.

Chronic Mucocutaneous Candidiasis due to Signal Transducer and Activator of Transcription 1 (STAT 1) Mutation in an Indian Patient - A Case Report.

Chronic mucocutaneous candidiasis (CMC) is a primary immunodeficiency due to defect in various genes leading to an increase in susceptibility to skin and mucosal infection. Mutation in signal transducer and activator of transcription 1 (STAT 1) gene being the most common cause of CMC can lead to increased risk of infections, multisystem abnormalities, and malignancy. We describe a 27 year old Indian woman with clinical features of CMC including esophageal stenosis, gangrene of the finger, endocrinological and immunological abnormalities and STAT1 mutation (p.Leu407Val). She was treated with antifungals which led to symptomatic improvement.

Genetic and immunologic findings in children with recurrent aphthous stomatitis with systemic inflammation.

BACKGROUND: Recurrent aphthous stomatitis with systemic signs of inflammation can be encountered in inflammatory bowel disease, Behçet's disease (BD), Systemic Lupus Erythematosus (SLE). In addition, it has been proposed that cases with very early onset in childhood can be underpinned by rare monogenic defects of immunity, which may require targeted treatments. Thus, subjects with early onset recurrent aphthous stomatitis receiving a clinical diagnosis of BD-like or SLE-like disease may deserve a further diagnostic workout, including immunologic and genetic investigations. OBJECTIVE: To investigate how an immunologic, genetic and transcriptomics assessment of interferon inflammation may improve diagnosis and care in children with recurrent aphthous stomatitis with systemic inflammation. METHODS: Subjects referred to the pediatric rheumatologist for recurrent aphthous stomatitis associated with signs of systemic inflammation from January 2015 to January 2020 were enrolled in the study and underwent analysis of peripheral lymphocyte subsets, sequencing of a 17-genes panel and measure of interferon score. RESULTS: We enrolled 15 subjects (12 females, median age at disease onset 4 years). The clinical diagnosis was BD in 8, incomplete BD in 5, BD/SLE overlap in 1, SLE in 1. Pathogenic genetic variants were detected in 3 patients, respectively 2 STAT1 gain of function variants in two patients classified as BD/SLE overlap and SLE, and 1 TNFAIP3 mutation (A20 haploinsufficiency) in patients with BD. Moreover 2 likely pathogenic variants were identified in DNASE1L3 and PTPN22, both in patients with incomplete BD. Interferon score was high in the two patients with STAT1 GOF mutations, in the patient with TNFAIP3 mutation, and in 3 genetic-negative subjects. In two patients, the treatment was modified based on genetic results. CONCLUSIONS: Although recurrent aphthous stomatitis associated with systemic inflammation may lead to a clinical diagnosis of BD or SLE, subjects with early disease onset in childhood deserve genetic investigation for rare monogenic disorders. A wider genetic panel may help disclosing the genetic background in the subset of children with increased interferon score, who tested negative in this study.

Oesophageal candidiasis and squamous cell cancer in patients with gain-of-function STAT1 gene mutation.

BACKGROUND: Oesophageal candidiasis is a common, usually self-limiting opportunistic infection, but long-term infection with Candida is known to predispose to oral and oesophageal squamous cell cancer (SCC). Permissive factors that lead to immune deficiencies can underlie persistent or recurring candidiasis, called chronic mucocutaneous candidiasis (CMC). Secondary immune deficiencies are most often due to human immunodeficiency virus (HIV) infection, antibiotic use and immunosuppressive treatment (steroids, chemotherapy). Inborn errors of the immune system (primary immune deficiencies) can present with isolated CMC known as CMC disease (CMCD), which is most often found in patients with autoimmune polyendocrinopathy syndrome type 1 (APS1)/APECED or in patients with an underlying gain-of-function STAT1 mutation (GOF-STAT1). OBJECTIVE: To describe a new form of inherited/familial CMC with a high risk for developing squamous cell carcinoma of the oesophagus, due to a gain-of-function mutation in the STAT1 gene. METHODS AND RESULTS: This report describes a family of patients with CMC with confirmed GOF-STAT1 mutation. These patients usually present with CMCD in childhood, have severe oral and oesophageal candidiasis accompanied by severe difficulty swallowing, chest pain, heartburn, and are at risk of developing oral and/or oesophageal SCC. This case series describes six patients in three generations of the same family, two of whom developed and died of SCC. We recommend regular endoscopic surveillance to detect early oesophageal neoplasia in patients with CMCD as well as urgent endoscopy in symptomatic patients. CONCLUSION: CMC is not a well-recognised condition in gastroenterology practice and clinicians need to be aware of the genetics of the condition as well as the risk for oesophageal cancer so that they can counsel their patients and arrange surveillance appropriately.