Does Age at Onset Affect the Clinical Presentation of Familial Mediterranean Fever in Children?

BACKGROUND/OBJECTIVE: The aim of this study was to compare the clinical and demographic features and evaluate the phenotypic and genotypic differences of pediatric familial Mediterranean fever (FMF) patients according to their age at disease onset.

METHODS

Records of 854 patients who were diagnosed with FMF between 2006 and 2017 were evaluated. Patients were divided into 2 subgroups according to their age at disease onset. Group 1 comprised FMF patients who had experienced their first attack at 2 years or younger (younger onset), and group 2 comprised FMF patients who had experienced their first attack at older than 2 years.

RESULTS

There were 155 patients in group 1 and 699 patients in group 2. Delay in diagnosis, attack frequency, duration of attacks, fever, chest pain, erysipelas-like erythema, incidence of family history, anti-interleukin 1 therapy use, and M694V homozygous and M680I homozygous mutations were significantly higher in group 1, whereas arthralgia and abdominal pain were significantly higher in group 2. There were no significant differences in arthritis, amyloidosis, and protracted febrile myalgia between the groups. The colchicine dose at last visit and Pras activity score were higher in group 1.

CONCLUSIONS

It seems that FMF patients with a younger onset has a more severe disease course. They needed higher doses of colchicine to control the attacks. M694V and M680I homozygous mutations presented more frequently in younger-onset FMF patients. Increased awareness of physicians of the early presentation of FMF may prevent delays in FMF diagnosis.