Comparing the patients with familial mediterranean fever according to the genotypic, phenotypic and laboratory findings

Familial Mediterranean Fever (FMF) is the most common hereditary recurrent fever syndrome. FMF belongs to the group of autoinflammatory diseases, pathogenetically. Main mechanism is thought to be activation of inflammation. The disease is clinically characterized by self-limited, recurrent episodes of fever, abdominal pain, chest pain, arthritis/arthralgia and erysipeloid rash. In this study, we aimed to define genotypic, phenotypic and laboratory findings of the FMF patients who were followed in our center.One hundred and thirty nine patients were included in this study. All of the cases were followed at Baskent University Faculty of Medicine, Ankara Hospital, Pediatric Nephrology Unit with MEFV mutation in at least one allelle and diagnosed with FMF according to the Tel Hashomer criteria (Male/female ratio close to 1). Demographic and laboratory data were collected retrospectively. The cases were classified as mild, intermediate and severe according to the scoring system developed by PRAS et al. Also the cases were subdivided into two cathegories according to age as ≤ 10 y Group 1 and >10 y Group 2. The genotypic, phenotypic and laboratory findings of those two groups were then compared.Median age of disease onset was 4 years (min-max: 2,75-17,9), median age of diagnosis was 6,6 years (min-max: 0,6-17,5) and median time elapsed until diagnosis was 2 years (min-max: 0,16-16,5). Among 75% of cases, M694V mutation were detected in at least one allelle. Patients presented with fever in 82,5%, with abdominal pain in 75,2% and with arthritis/arthralgia in 24,1%. The incidence of amyloidosis was 2%. There was no statistically significant relation between severity of the disease and type of mutations. PRAS disease severity scores were significantly higher among the group with M694V mutation in at least one allelle than those do not carry the mutation (6,45±1,48, 5,68±1,87, respectively, p=0,016). PRAS disease severity scores of the M694V homozygous patients were significantly higher than the patients without the mutation (6,86±1,43, 5,00±1,22, respectively, p=0,011). Patients in Group 1 (≤ 10 y) admitted with fever at a significantly higher rate than the patients in Group 2 (>10 y). On the contrary, rate of chest pain on admission was significantly higher among Group 2. WBC count, CRP and ESR levels were significantly higher in Group 1 during exacerbation (p<0,05). PRAS disease severity score was significantly higher in Group 1 than Group 2 (6 (min-max:4-10), 4 (min-max:3-7), respectively, p=0,021).It was found that M694V was the most common mutation among our cases. We concluded that patients carrying M694V mutation and diagnosed with disease younger than the age of 10 had worse prognosis. Considering the conflicting results in the literature, we are in the opinion that, there is need for further studies aiming establishment of severity of disease classification systems specific for pediatric population.