FMF is caused by “gain of function” mutations in the MEFV gene, which is located on the short arm of chromosome 16p13.3, composed of 10 exons and coding for a 781-amino acid protein called “pyrin or marenostrin,” an important regulator of the innate immune response.7 Classical FMF is an autosomal recessive disease caused by homozygous or compound heterozygous mutations in the MEFV gene. Here, MEFV is linked to familial Mediterranean fever.