Aim: This study aimed to present the demographic, clinical, and laboratory features of children clinically diagnosed with familial Mediterranean fever (FMF) and to predict more severe mutations by evaluating those findings.
Methods: We enrolled cases diagnosed with FMF with a defined variation in at least one allele. The medical charts of the patients were reviewed retrospectively. The patients were grouped as homozygous, compound heterozygous, and simple heterozygous cases, with and without M694V mutation. We compared the data between the subgroups using logistic regression analysis and determined the risk factors for being homozygous or compound heterozygous for M694V.
Results: A total of 263 (M/F =109/154) cases were included. The mean age at the onset of symptoms, follow-up duration, and time to diagnosis were 6.75 ± 3.9 (0.25-17) years, 51.78 ± 39.31 (6-166) months, and 9.23 ± 14.44 (1-132) months, respectively. The rates of parental consanguinity, positive family history for FMF, and FMF in a first-degree relative were 15%, 42%, and 31.4% respectively. The most common symptom was abdominal pain (85%). There was no difference between the growth parameters of the cases during the initial and final control periods. The most frequent alleles were M694V, E148Q, and V726A. The most common accompanying disease was IgA vasculitis (20%). Almost 90% of the cases fulfilled all the defined criteria. The rate of patients having a first-degree relative with FMF was higher, Hb values were lower, and the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) values were higher during the attack period; the ESR and CRP values were higher in the attack-free period; and Pras disease severity scores were higher in homozygous or compound heterozygous cases carrying M694V. The presence of FMF in a first-degree relative increases the probability of being homozygous and compound heterozygous for M694V by a factor of 2.39; and each 1 unit increase in the Pras score increases this probability by a factor of 1.43. The threshold Pras score for this possibility is 5.5 (AUC = 0.651; 95% CI, 0.545-0.757; P = .006; sensitivity, 65%; specificity, 55%).
Conclusion: M694V was the most common and severe mutation in our cohort. The presence of a first-degree relative with FMF and Pras scores ≥5.5 may predict a homozygous or compound heterozygous mutation for M694V.