Familial Mediterranean fever in Lebanon: mutation spectrum, evidence for cases in Maronites, Creek orthodoxes, Creek catholics, Syriacs and Chiites and for an association between amyloidosis and M694V and M6941 mutations

Seventy-nine unrelated Lebanese patients were tested for 15 mutations in the MEFV gene: A761H, A744S, V726A, K695R, M694V, M694I, M694del, M6801 (G --> C), M6801 (G --> A) in exon 10, F479L in exon 5, P369S in exon 3, T267I, E167D and E148Q in exon 2 using PCR digestion, ARMS, DGGE and/or sequencing. Mutations were detected in patients belonging to all communities, most interestingly the Maronite, Greek orthodox, Greek catholic, Syriac and Chiite communities. The most frequent mutations are M694V and V726A (27% and 20% of the total alleles respectively). M6941, E148Q and M6801 mutations account respectively for 9%, 8% and 5%. Each of the K695R, E167D and F479L mutations was observed once and all the remaining mutations were not encountered. Of the alleles 33% do not carry any of the studied mutations. The mutation spectra, clinical features and severity of the disease differed among the Lebanese communities. The genotype-phenotype analysis showed a significant association (P < 0.001) between amyloidosis and the presence of mutations at codon 694 in exon 10 (both M694V and M6941). None of the patients carrying other mutations developed amyloidosis.