NLRP12-associated hereditary periodic fever syndrome

NLRP12-associated hereditary periodic fever syndrome (also known as familial cold autoinflammatory syndrome 2, or FCAS2) is a rare autoinflammatory disorder caused by mutations in the NLRP12 gene (also called MONARCH-1 or PYPAF7). This gene encodes a protein involved in the regulation of the innate immune system, particularly in the NF-κB inflammatory signaling pathway. When the protein is dysfunctional, the body's inflammatory response becomes dysregulated, leading to recurrent episodes of systemic inflammation. The condition typically presents in early childhood with recurrent episodes of fever, often triggered by cold exposure. Key clinical features include urticaria-like skin rash, joint pain (arthralgia), myalgia (muscle pain), headache, and lymphadenopathy (swollen lymph nodes). Some patients may also experience oral ulcers, abdominal pain, and fatigue during flares. Episodes are generally self-limiting but can significantly impact quality of life. The disease primarily affects the immune system, skin, musculoskeletal system, and lymphatic system. In some cases, sensorineural hearing loss has been reported. Treatment is largely supportive and aimed at controlling inflammation during flares. Nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids may be used for symptom management. Given the autoinflammatory nature of the disease, biologic therapies targeting interleukin-1 (IL-1), such as anakinra, have been explored in some patients with variable response. Long-term monitoring is important to assess for potential complications, including secondary amyloidosis (AA amyloidosis), which is reflected in the assigned ICD-10 code E85.0. Due to the rarity of the condition, management is best guided by specialists experienced in autoinflammatory diseases.

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