Association of clinical and genetical features in FMF with focus on MEFV strip assay sensitivity in 452 children from western Anatolia, Turkey

The aim of this study was to determine the relationship between clinical findings and the most common mutated alleles of MEFV gene in a childhood population and to determine the sensitivity of the 12-mutation-strip assay test in familial Mediterranean fever (FMF). Records of 452 FMF children living in western Anatolia, Turkey, (12.3 ± 4.7 years mean) were retrospectively reviewed. Of the 408 patients who met the Tel-Hashomer criteria, 364 were classified into two main groups (two-mutant/one-mutant allele) either of which had three subgroups. The two-mutant allele frequency was 51% and one-mutant allele 38%; 1% had complex-mutant alleles and 10% no mutant-alleles. The mean severity score was 8.3 ± 2.5. Most common clinical features were fever (81.9%), abdominal pain (86.3%) and myalgia (58.8%), and the least common ones: diarrhea (1.7%), protracted febrile myalgia (1.2%) and acute orchitis (1.5%). We detected 33 different genotypes of the MEFV gene: the most common mutant allele was M694V followed by symptomatic allele mutation of E148Q. Although not significantly associated with clinical findings, P369S mutation was not rare (7.5%). Phenotype–genotype correlation revealed that patients with two-allele mutations had more severe clinical presentation and high constipation rate (22.5%); 32.6% of patients with M694V/M694V had splenomegaly. Acute orchitis and protracted febrile myalgia as rare clinical findings were more common in M694V homozygotes. Comparisons of clinical findings among patients with one-mutation allele were made for the first time, but no significant association was found. Positive predictive value of strip assay screening for 12 mutations was recorded as 89%. We suggest that whole sequence analysis for supportive diagnosis of FMF should be performed for selected patients only.