Periodic Fever Syndrome (PFS)
These conditions refer to a group diseases that cause periodic fevers that are not caused by a viral or bacterial infection. In general, children who are between episodes or cycles, are fine. Many of these syndromes are hereditary (passed down from parents) and result from a mutation (defect or mistake) in a gene (this is the code that determines the structure of our proteins). Many of these syndromes have a specific treatment, often based on understanding the problem caused by the genetic defect.
The most common type of PFS is Familial Mediterranean Fever (FMF). Patients with FMF suffer from Patients suffer from recurrent episodes of fever, accompanied by abdominal, chest and joint pain and swelling. The disease generally affects people of Mediterranean and Middle Eastern descent, typically Sephardic Jews, Turks, Arabs and Armenians. Since the discovery of the gene defect, it is being diagnosed more frequently, even among populations where it was thought to be very rare, such as Italians, Greeks and Ashkenazi Jews. FMF episodes start before the age of 20 years in approximately 90% of the patients. In more than half of them the disease appears before the age of 10 years.
Usually, only one joint is affected at a time, most commonly an ankle or a knee. The joint may be so swollen and painful that the child cannot walk. In about a third of these patients there is a red rash over the involved joint. In some children, the sole finding of the disease may be episodes of joint pain and swelling, which is misdiagnosed as acute rheumatic fever, or juvenile idiopathic arthritis. Usually the joint swelling resolves over 5-14 days. In about 5-10% of cases the joint involvement may become chronic. Some children report muscle pain in the legs.
Rarely, children have recurrent pericarditis (inflammation of the outer layer of the heart), myositis (muscle inflammation), meningitis (inflammation of the membrane surrounding the brain and spinal cord) and orchitis (testicular inflammation). Frequent attacks can affect the child's and family’s life, including school attendance.
The most severe complication of FMF if untreated is the development of amyloidosis. Amyloid is a protein that deposits in certain organs in children with chronic inflammatory diseases that are not well controlled. The most common organ involved is the kidney, but amyloid can deposit in the gut, skin and heart. Eventually amyloid causes a loss of function, especially of the kidneys. Children who are properly treated (see below under medications) are safe from the risk of developing this life-threatening complication
Can it occur in adults? Yes, but often the disease is milder and less obvious (thus harder to diagnose) than in children. The risk of amyloidosis is lower in adult onset disease.
FMF cannot be cured, but it can be well controlled with life-long use of colchicine. In this way, episodes can usually be prevented (in 60% of patients completely prevented, in 33% partially prevented, and in about 5% colchicine is not effective) and amyloidosis can be prevented in 100% of patients. If the patient stops taking the drug, episodes (often after missing only one dose!) and the risk of amyloidosis may return. Compliance (taking the medicine as recommended) is very important. If colchicine is taken regularly the child can live a normal life with a normal life expectancy. The patient or the parents should not change the medication dose without discussing this first with the doctor. Some children initially need psychological support for a disease that means taking medications for their entire life. Colchicine prevents episodes from starting but does not treat an episode that has already started. Therefore, the dose of colchicine should not be increased during an already active episode.