Familial Mediterranean Fever (FMF) is a genetic inflammatory disorder causing recurrent episodes of fever and inflammation throughout the body. These episodes, known as “attacks,” can impact various organs and systems. A distinctive rash is among the notable symptoms associated with FMF, often providing an important clue for diagnosis.
What is Familial Mediterranean Fever?
Familial Mediterranean Fever is an inherited condition primarily caused by mutations in the MEFV gene, located on chromosome 16. This gene is responsible for producing a protein called pyrin, which plays a role in regulating the body’s inflammatory response. When mutations occur in the MEFV gene, pyrin’s function is disrupted, leading to uncontrolled inflammation and the characteristic FMF attacks.
Individuals with FMF experience recurrent, self-limiting inflammatory episodes that typically last between one and four days. These attacks often involve a sudden onset of fever, which can reach up to 104 degrees Fahrenheit (40 degrees Celsius). Common accompanying symptoms include severe abdominal pain from abdominal lining inflammation, chest pain due to lung or heart membrane inflammation, and joint pain, often affecting the knees, ankles, or hips. Triggers for these episodes can include emotional stress, physical exertion, infection, or menstruation.
The Distinctive FMF Rash
The rash associated with Familial Mediterranean Fever is often described as an “erysipelas-like erythema,” mimicking a bacterial skin infection. This characteristic rash appears as red, warm, tender, and sometimes swollen patches on the skin. It is typically found on the lower legs, ankles, and feet, though it can occur in other areas.
The FMF rash is self-limiting, resolving within one to three days, similar to other FMF symptoms. While a red rash on the lower extremities affects about one-third of patients, it does not occur with every attack.
Identifying and Treating FMF
Diagnosing Familial Mediterranean Fever involves a combination of clinical criteria, family history evaluation, and genetic testing. Doctors consider recurrent fevers and inflammatory attacks, such as abdominal pain, chest pain, or joint pain, as part of the diagnostic process. A family history of FMF can also provide significant clues. Genetic testing for mutations in the MEFV gene helps confirm the diagnosis, although approximately 10% of patients who meet clinical criteria may not show a detectable mutation.
The primary treatment for FMF is daily administration of colchicine, a medication that helps reduce inflammation. Colchicine prevents FMF attacks and decreases the risk of developing amyloidosis, a serious complication where abnormal proteins build up in organs, particularly the kidneys. Dosing varies by age: children under 5 years typically start at 0.5 mg/day, children aged 5-10 at 0.5-1.0 mg/day, and those over 10 years and adults at 1.0-1.5 mg/day. For cases resistant to colchicine or in patients who cannot tolerate it, other treatments, such as interleukin-1 (IL-1) blockers like anakinra or canakinumab, may be considered. Effective management of FMF and prevention of long-term complications depend on early diagnosis and consistent adherence to treatment.