Familial Mediterranean fever (FMF ,recurrent polyserositis ,periodic disease) is an autosomal recessive auto inflammatory disease which primarily affect population surrounding the Mediterranean basin (Arabs , Turks ,Armenians, Jews ).Despite its striking symptoms pattern FMF was first described as distinct entity only in 1945.

It is characterized by recurrent attacks of fever , peritonitis ,pleurisy , arthritis , or erysipelas like skin disease. The most dangerous complication of this disease is secondary amyloidosis . FMF diagnosis is mainly clinical, and the genetic testing is indicated to support it . Uncommonly, amyloidosis may develop in individuals carrying two Familial Mediterranean fever gene (MEFV ) mutations without overt clinical symptoms of FMF, a condition designated as phenotype II. Furthermore, two MEFV mutations may be harbored without signs or symptoms of FMF nor of reactive amyloidosis. This 'silent' homozygous or compound heterozygote state is termed phenotype III.

Inclusion Criteria:

A- all children diagnosed as FMF according to Tel hashomer criteria aged below 18 years:

The presence of at least 2 of the following 5 criteria after exclusion of other causes can diagnose FMF with high sensitivity:

1. Fever axillary temperature of >38ᵒC, 6-72 h of duration, ≥3 attacks
2. Abdominal pain 6-72 h of duration ≥3 attacks
3. Chest pain 6-72 h duration≥ 3 attacks
4. Arthritis 6-72 h duration ≥3 attacks, oligoarthritis
5. Family history of FMF*(11) B-sisters and brothers of a child with FMF with clinical or subclinical manifestation of FMF.

Exclusion Criteria:

1. Children with other auto inflammatory diseases, or with other diseases.
2. Persons above 18 years old.