MEFV gene mutations in children with Henoch–Schönlein purpura and their correlations—do mutations matter? Abstract Objective To explore the frequency of MEFV gene mutations in children with Henoch–Schönlein purpura who had no prior familial Mediterranean fever diagnosis and to evaluate the association of MEFV mutations with the clinical and laboratory features of Henoch–Schönlein purpura. Methods Data of 1120 patients diagnosed with Henoch–Schönlein purpura were reviewed retrospectively. The spectrum and degree of organ involvement and acute phase reactant levels were documented for each patient. Blood for MEFV gene mutation analysis was obtained either at the time of the Henoch–Schönlein purpura diagnosis or during follow-up visits. Pathological specimens of patients who underwent biopsy (renal/skin) were evaluated with special consideration for immunofluorescent examinations. Results Two hundred and thirty-eight (21.3%) patients were found to have one of the MEFV mutations in which exon 10 mutations were the most common (16.7%). Abdominal pain, joint involvement, scrotal involvement, and relapse were more frequent, and acute-phase reactant levels were significantly high in patients with MEFV mutations. More severe characteristics were observed in the presence of homozygous exon 10 mutations. There was no significant association between exon 2 variants and clinical course of Henoch–Schönlein purpura. Patients carrying MEFV mutations did not have significantly higher levels of IgA deposits in the biopsy materials. Conclusion Henoch–Schönlein purpura in patients with homozygous exon 10 MEFV mutations seems to be more severe than that in patients carrying other mutations. In patients with exon 10 MEFV mutations, Henoch–Schönlein purpura might be considered as an associated presentation of familial Mediterranean fever rather than a separate clinical entity. Key points • p.M694V mutation is more common in Henoch–Schönlein purpura than in the general population. • p.E148Q variants have no impact on clinical symptoms and laboratory findings in Henoch–Schönlein purpura patients. • The majority of Henoch–Schönlein purpura patients with familial Mediterranean fever have no IgA deposits. • Henoch–Schönlein purpura in familial Mediterranean fever patients may be considered as an integral clinical feature of familial Mediterranean fever.