Objective: Familial Mediterranean fever (FMF) is the most prevalent monogenic autoinflammatory disease worldwide. The diagnosis is primarily clinical, based on severity of the disease, and confirmed by mutations of the MEFV gene. The aim of this study was to evaluate the effect of exon-2 genotypic variants on clinical signs and symptoms and the severity of FMF in children in comparison with those with an exon-10 genotypic variant.
Materials and Methods: The demographic, clinical, and laboratory data of 164 pediatric FMF patients were evaluated. The patients were classified into 3 groups according to MEFV mutations: patients with a variation in only the exon-2 genotype, both the exon-2 and exon-10 genotypes, and only the exon-10 genotype.
Results: There was no statistically significant difference between the 3 groups in terms of the sex or age at diagnosis, medical history of recurrent tonsillitis, history of appendectomy, or anthropometric features (p>0.05, for both parameters). However, the median age at the first attack was significantly lower in patients with only an exon-10 genotypic variant (median: 4.16 years [interquartile range: 2.5-5.5 years]) (p=0.038). Evaluation of the clinical features of all of the groups revealed that the frequency of attack and attack-free period symptoms were similar (p>0.05). However, the median disease severity score was lower in patients with only exon-2 genotypic variants than patients with exon-10 and compound heterozygous genotype variants (p=0.017).
Conclusion: FMF should be carefully evaluated according to the genotypic and phenotypic characteristics; all potential MEFV gene mutations should be considered. Variants of exon-2 appear to result in milder clinical symptoms in comparison with exon-10 variants.