Genotype-phenotype associations in familial Mediterranean fever: a study of 500 Egyptian pediatric patients

Introduction Familial Mediterranefeveran (FMF) is the most prevalent monogenic autoinflammatory disease, caused by recessively inherited MEFV gene mutations. The most frequent MEFV mutations differ in penetrance and disease severity. We investigated the genotype-phenotype associations of the three most frequent MEFV gene mutations (M680I, M694V, and V726A) in Egyptian FMF children, regarding clinical features, severity, and colchicine response. Methods We conducted a retrospective analysis of the medical registries of 500 FMF pediatric patients from Metropolitan Cairo between 2010 and 2015. The diagnosis was based on the Tel-Hashomer clinical diagnostic criteria. Clinical data and baseline investigations were collected. Mutation analysis was performed by the amplification-refractory mutation system (ARMS)-PCR method. Results:Males represented 54% and ages ranged from 2 to 18 years. The most frequent symptoms were abdominal pain, fever, and arthralgia. Clinical features mostly associated with M694V mutation either homozygous or heterozygous whether simple, double, or triple. Of the patients, 94.6% completely responded to colchicine. Among patients benefiting from colchicine, 42.5% had M694V/V726A, 21.6% had M694V/V726A/M680I, and 21.1% had M694V genotype. Simple heterozygous M694V or V726A mutations conveyed a moderate phenotype in 57.1% and 50% of cases, respectively. Homozygous M694V mutation showed moderate and severe phenotypes in 21.7% and 65.2% of cases, respectively. Compound M694V/V726A mutation associated with moderate or severe disease in 48.3% and 33.8% of cases, respectively. Conclusion This study encompasses the largest group of Egyptian pediatric FMF up to date to explore their genotype-phenotype associations. Our results support the notion that the genotype influences the phenotype as regards clinical manifestations, disease severity, and colchicine response.