Abstract: Dominant mutations in the CIAS1 gene cause a spectrum of autoinflammatory diseases such as familial cold autoinflammatory syndrome, FCAS, which is characterized by episodes of urticaria, arthralgia, fever and conjunctivitis after generalized exposure to cold. We here describe patients of two German families with the 592G→A, V198M mutation, which has been described to induce FCAS before. However, in our patients the clinical phenotype was very different from this disease. They never had urticaria, cold induced fever or conjunctivitis; instead the following symptoms occurred: Very regular periodic fever, irregular severe febrile episodes, relatively mild arthralgia, dry cough, cardiomyopathy, nephropathy and euthyroid thyroiditis all being reversible. We conclude that the clinical phenotype associated with mutations in the CIAS1 gene is much broader than assumed before.