Clinical Significance of R202Q Alteration of MEFV Gene in Children With Familial Mediterranean Fever
Tufan ÇANKAYA1, Elçin BORA1, Meral TORUN BAYRAM2, Ayfer ÜLGENALP1, Salih KAVUKÇU2, Mehmet Atilla TÜRKMEN2, Alper SOYLU2
1Department of Pediatric Genetics, Medical Faculty of Dokuz Eylül University, İzmir, Turkey
2Department of Pediatric Nephrology, Medical Faculty of Dokuz Eylül University, İzmir, Turkey
Keywords: Children, familial Mediterranean fever, R202Q alteration of MEFV gene
Objectives: This study aims to investigate the clinical impact of the R202Q (c.605G>A) alteration of Mediterranean fever (MEFV) gene in children with familial Mediterranean fever (FMF).
Patients and methods: Medical records of 115 patients (51 males, 64 females; mean age 6.6±3.8 years; range 8 months to 15.8 years) presenting with FMF pre-diagnosis were examined. Patients were classified into two groups based on number of mutated alleles (one-mutant allele and two mutant alleles), and these groups were classified into three subgroups (Group 1; subgroup 1: M694V/R202Q, subgroup 2: M694V/other, subgroup 3: other/other, and Group 2; subgroup 4: R202Q/-, subgroup 5: other/-, subgroup 6: -/-). Sex, age, abdominal pain, fever, arthritis or arthralgia, myalgia, erysipelas-like erythema, chest pain, amyloidosis, family history of FMF, and definitive FMF frequency were compared between groups.
Results: The most common allele alterations were the heterozygous R202Q alteration (27%) and the compound heterozygous mutation M694V/ R202Q (20.9%). The R202Q alteration of MEFV gene was detected in 76 patients (66%) (15 homozygous). There was non-M694V (E148Q, V726A) mutation in two of these patients. One (50%) of the patients with isolated R202Q homozygous alteration and six (19%) of the patients with isolated R202Q heterozygous alteration had definitive FMF. In the two-mutant allele group; abdominal pain, fever, arthritis/arthralgia, and definitive FMF frequency were lower in subgroup 1 than subgroup 2. There was no significant difference in clinical findings and definitive FMF frequency between subgroup 2 and subgroup 3. In the one-mutant allele group, clinical findings did not differ between subgroups.
Conclusion: R202Q alteration of the MEFV gene may lead to symptoms consistent with FMF. However, R202Q/M694V compound heterozygosity is more associated with mild phenotype than compound heterozygous mutation of M694V.