Unusual Systemic Lupus Erythematosus/Sjogren's Syndrome Phenotype in a Patient with a TNFAIP3 Gene Mutation

A 4-year-old Caucasian female with a heterozygous mutation in the TNFAIP3 gene (c.811C>T; p.(Arg271*)) presented with an unusual phenotype of systemic lupus erythematosus (SLE) and Sjogren's syndrome (SS). Her symptoms included photosensitive malar rash, mouth ulcers, hair loss, and more. Laboratory tests confirmed SLE, and treatment with hydroxychloroquine, azathioprine, and oral steroids was initiated. Genetic screening revealed the same mutation in her asymptomatic mother. The child later developed lupus nephritis, and azathioprine was replaced with mycophenolate mofetil. After one year, her symptoms improved, and prednisolone was tapered off. This case expanded the known phenotype associated with the TNFAIP3 mutation, highlighting its variable penetrance and blurring the lines between autoinflammatory and autoimmune diseases.