The hereditary periodic fever syndromes or hereditary autoinflammatory diseases are disorders of innate immunity that mostly present in childhood and are characterized by recurrent, self-limiting, seemingly unprovoked episodes of fever and systemic inflammation that occur in the absence of autoantibody production or identifiable infection. Disorders include (1) familial Mediterranean fever (FMF), due to mutations in the gene encoding pyrin; (2) tumour necrosis factor (TNF) receptor-associated periodic syndrome (TRAPS), due to mutations in a gene for a TNF receptor; (3) mevalonate kinase deficiency and period fever (MKD), caused by mutations in the mevalonate kinase gene; and (4) the cryopyrin-associated periodic syndromes (CAPS), which include (a) familial cold urticarial syndrome, (b) Muckle–Wells syndrome, and (c) chronic infantile neurological, cutaneous, and articular syndrome. With advances in genetics, further syndromes are continually being recognized. These are all extremely rare and in the majority are only known to affect a handful of kindred or individuals. Diagnosis relies on recognition of suggestive clinical features that are almost always accompanied by a substantial acute phase response, and is supported by genetic testing. With the exception of FMF, which is a common disease in certain geographic areas, hereditary periodic fever syndromes are rare and easily overlooked in the differential diagnosis of recurrent fevers. Clinical features and management—attacks can be mild to debilitating and short to prolonged, while their most feared complication is AA amyloidosis. Effective therapies are available for some syndromes, for example: (1) FMF—daily prophylactic colchicine prevents clinical attacks and susceptibility to AA amyloidosis, (2) CAPS—treatment with anti-IL-1 agents produces rapid and often complete clinical and serological remission, and (3) TRAPS—anti-IL therapies are extremely effective.
Brief Report: AA Amyloidosis Complicating the Hereditary Periodic Fever Syndromes
