Periodic fever syndrome

{{See also|Autoinflammatory diseases}}

{{Infobox medical condition (new)

| name = Periodic fever syndrome

| synonyms = Autoinflammatory diseases or Autoinflammatory syndromes

| image =

| caption =

| pronounce =

| field = Rheumatology, Immunology

| symptoms =

| complications =

| onset =

| duration =

| types =

| causes =

| risks =

| diagnosis =

| differential =

| prevention =

| treatment =

| medication =

| prognosis =

| frequency =

| deaths =

}}

Periodic fever syndromes are a set of disorders characterized by recurrent episodes of systemic and organ-specific inflammation. Unlike autoimmune disorders such as systemic lupus erythematosus, in which the disease is caused by abnormalities of the adaptive immune system, people with autoinflammatory diseases do not produce autoantibodies or antigen-specific T or B cells. Instead, the autoinflammatory diseases are characterized by errors in the innate immune system.Masters SL, Simon A, Aksentijevich I, et al. Horror autoinflammaticus: the molecular pathophysiology of autoinflammatory disease*. Annu Rev Immunol 2009;27(1):621–68

The syndromes are diverse, but tend to cause episodes of fever, joint pains, skin rashes, abdominal pains and may lead to chronic complications such as amyloidosis.{{cite journal |vauthors=Stojanov S, Kastner DL |title=Familial autoinflammatory diseases: genetics, pathogenesis and treatment |journal=Curr Opin Rheumatol |volume=17 |issue=5 |pages=586–99 |year=2005 |pmid=16093838 |doi=10.1097/bor.0000174210.78449.6b|s2cid=25948105 |url=https://zenodo.org/record/1234873 }}

Most autoinflammatory diseases are genetic and present during childhood.{{cite journal|last1=Hausmann|first1=JS|last2=Dedeoglu|first2=F|title=Autoinflammatory diseases in pediatrics.|journal=Dermatologic Clinics|date=July 2013|volume=31|issue=3|pages=481–94|doi=10.1016/j.det.2013.04.003|pmid=23827250}} The most common genetic autoinflammatory syndrome is familial Mediterranean fever, which causes short episodes of fever, abdominal pain, serositis, lasting less than 72 hours. It is caused by mutations in the MEFV gene, which codes for the protein pyrin.{{cn|date=July 2022}}

Pyrin is a protein normally present in the inflammasome. The mutated pyrin protein is thought to cause inappropriate activation of the inflammasome, leading to release of the pro-inflammatory cytokine IL-1β. Most other autoinflammatory diseases also cause disease by inappropriate release of IL-1β.{{cite journal|last1=Jamilloux|first1=Y|last2=Bourdonnay|first2=E|last3=Gerfaud-Valentin|first3=M|last4=Py|first4=BF|last5=Lefeuvre|first5=L|last6=Barba|first6=T|last7=Broussolle|first7=C|last8=Henry|first8=T|last9=Sève|first9=P|title=[Interleukin-1, inflammasome and autoinflammatory diseases].|journal=La Revue de Médecine Interne|volume=39|issue=4|pages=233–239|date=14 September 2016|pmid=27639913|doi=10.1016/j.revmed.2016.07.007}} Thus, IL-1β has become a common therapeutic target, and medications such as anakinra, rilonacept, and canakinumab have revolutionized the treatment of autoinflammatory diseases.{{cn|date=July 2022}}

However, there are some autoinflammatory diseases that are not known to have a clear genetic cause. This includes PFAPA, which is the most common autoinflammatory disease seen in children, characterized by episodes of fever, aphthous stomatitis, pharyngitis, and cervical adenitis. Other autoinflammatory diseases that do not have clear genetic causes include adult-onset Still's disease, systemic-onset juvenile idiopathic arthritis, Schnitzler syndrome, and chronic recurrent multifocal osteomyelitis. It is likely that these diseases are multifactorial, with genes that make people susceptible to these diseases, but they require an additional environmental factor to trigger the disease.{{cn|date=July 2022}}