FMF is the most frequent hereditary recurrent inflammatory disorder. This disease affects mainly populations of Mediterranean descent: Arabs from the East as well as from the West, Armenians, Turks, non-Ashkenazi and other Jews, Druzes, Lebanese, Italians, and Greeks.[11]Ben-Chetrit E, Levy M. Familial Mediterranean fever. Lancet. 1998 Feb 28;351(9103):659-64.
http://www.ncbi.nlm.nih.gov/pubmed/9500348?tool=bestpractice.com
[12]Özen S. Update on the epidemiology and disease outcome of familial Mediterranean fever. Best Pract Res Clin Rheumatol. 2018 Apr;32(2):254-60.
http://www.ncbi.nlm.nih.gov/pubmed/30527430?tool=bestpractice.com
Patients have also been reported in Europe, North America, and Japan.[13]Tufan A, Lachmann HJ. Familial Mediterranean fever, from pathogenesis to treatment: a contemporary review. Turk J Med Sci. 2020 Nov 3;50(si-2):1591-610.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7672358
http://www.ncbi.nlm.nih.gov/pubmed/32806879?tool=bestpractice.com
Turkey and Armenia have the highest estimated FMF prevalence, at 1:1000 and 1:500, respectively.[12]Özen S. Update on the epidemiology and disease outcome of familial Mediterranean fever. Best Pract Res Clin Rheumatol. 2018 Apr;32(2):254-60.
http://www.ncbi.nlm.nih.gov/pubmed/30527430?tool=bestpractice.com
The reported gene carrier frequency is 1:5 in non-Ashkenazi Jews, 1:16 in Arabs, 1:5 in Turks, and 1:7 in Armenians.[12]Özen S. Update on the epidemiology and disease outcome of familial Mediterranean fever. Best Pract Res Clin Rheumatol. 2018 Apr;32(2):254-60.
http://www.ncbi.nlm.nih.gov/pubmed/30527430?tool=bestpractice.com
High prevalence explains the pseudo-dominant mode of inheritance observed in these populations. Prevalence is extremely rare among people of non-Mediterranean descent.[14]Tunca M, Ozdogan H. Molecular and genetic characteristics of hereditary autoinflammatory diseases. Curr Drug Targets Inflamm Allergy. 2005 Feb;4(1):77-80.
http://www.ncbi.nlm.nih.gov/pubmed/15720239?tool=bestpractice.com
[15]Tchernitchko D, Moutereau S, Legendre M, et al. MEFV analysis is of particularly weak diagnostic value for recurrent fevers in Western European Caucasian patients. Arthritis Rheum. 2005 Nov;52(11):3603-5.
http://onlinelibrary.wiley.com/doi/10.1002/art.21408/full
http://www.ncbi.nlm.nih.gov/pubmed/16255051?tool=bestpractice.com
There are also reports of occurrence in Melungeon populations (tri-racial mix of European, sub-Saharan African, American Indian, and Mediterranean origins living mostly in the Appalachian region) within the US.
The majority of patients (80% to 90%) have their first attack before age 20 years.[13]Tufan A, Lachmann HJ. Familial Mediterranean fever, from pathogenesis to treatment: a contemporary review. Turk J Med Sci. 2020 Nov 3;50(si-2):1591-610.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7672358
http://www.ncbi.nlm.nih.gov/pubmed/32806879?tool=bestpractice.com
Among paediatric populations, 20% have their first attack before age 2 years and 86% before age 10 years.[16]Majeed HA, Rawashdeh M, el-Shanti H, et al. Familial Mediterranean fever in children: the expanded clinical profile. QJM. 1999 Jun;92(6):309-18.
http://qjmed.oxfordjournals.org/content/92/6/309.long
http://www.ncbi.nlm.nih.gov/pubmed/10616706?tool=bestpractice.com
Males usually comprise 60% of patients. Among those with amyloidosis, the male to female ratio is 2:1.[17]Gershoni-Baruch R, Brik R, Lidar M, et al. Male sex coupled with articular manifestations cause a 4-fold increase in susceptibility to amyloidosis in patients with familial Mediterranean fever homozygous for the M694V-MEFV mutation. J Rheumatol. 2003 Feb;30(2):308-12.
http://www.ncbi.nlm.nih.gov/pubmed/12563686?tool=bestpractice.com