Analysis of the Most Common Three MEFV Mutations in 630 Patients with Familial Mediterranean Fever in Iranian Azeri Turkish Population. INTRODUCTION: The aim of the present study was to determine the frequency of M694V, M680I and V726A mutations of the MEFV gene in 630 Azeri Turkish patients with family Mediterranean fever. MATERIAL AND METHODS: The MEFV gene mutations were detected using allele-specific oligonucleotide polymerase chain reaction. OUTCOMES: 630 cases with a mean age ± SD of 28.54±16.54 ranging from 2.5 to 76 years old including 268 (42.54%) males and 362 (57.46%) females, were tested. Nineteen patients were homozygote for one mutation (3.02%), 127 were heterozygote for one mutation (20.2%) and 18 were compound heterozygote for two mutations (2.86%). Mutation analysis confirmed that the most common mutation was M694V 109 (8.65%). V726A and M680I mutations accounted for 4.44% of the alleles; V726A 32 (2.54%) and M680I 24 (1.9%). In this study, compound heterozygote for M694V and V726A, M694V and M680I, and V726A and M680I mutations were found in 1.43%, 0.79%, and 0.63% from West Azerbaijan province in exon 10. Mutation was found in 164 (26.03%) of cases regarding analysis of the three most common MEFV mutations, but in 466 (73.97%) of cases, no mutation was detected. Among our samples, the frequencies of mutant genotypes were 15 (2.38%), 1 (0.15%), 3 (0.47%), 9 (1.42%), 4 (0.63%) and 5 (0.79%), regarding M694V/M694V, M680I/M680I, V726A/V726A, M694V/ V726A, M680I/ V726A and M680I/ M694V, respectively. In our samples, 79 (12.53%), 26 (4.12%), and 22 (3.49%) cases had M694V/normal, V726A/normal, and M680I/normal genotypes regarding M694V, V726A, and M680I mutations, respectively. CONCLUSIONS: The M694V mutation is the most common risk factor for family Mediterranean fever in our group.