The analysis of genotype-phenotype correlation in familial Mediterranean fever.

Background: Familial Mediterranean fever (FMF) is the most common monogenic autoinflammatory disease manifesting with phenotypic heterogeneity. It is a clinically diagnosed disease supported by Mediterranean fever gene mutation analysis. This medical record review study aimed to make a new interpretation of clinical features in FMF patients by grouping genetic results based on the classification proposed by the Eurofever/ Paediatric Rheumatology International Trials Organisation.
Methods: The medical charts of pediatric FMF patients who were diagnosed and followed up regularly at the two pediatric rheumatology units were reviewed. Genetic analysis results were classified as confirmatory and nonconfirmatory as defined in the new Eurofever/ Paediatric Rheumatology International Trials Organisation classification criteria, and they were compared with clinical findings.
Results: A total of 216 FMF patients were involved in the study. Group 1 was composed of 133 (61.6%) patients with a confirmatory mutation and group 2 included 83 (38.4%) patients with a nonconfirmatory mutation. All clinical findings were compared, and in terms of fever (P = 0.027), abdominal pain (P = 0.016), arthritis (P = 0.008) and erysipelas-like erythema (ELE; P = 0.003) incidence, there was a significant difference between the two groups. The most common Mediterranean fever gene mutation patterns were homozygous (33.8%) and heterozygous (17.1%) mutations of M694V. The frequency of arthritis and ELE in patients with M694V homozygous mutations was significantly higher than in the other patients (P = 0.002 and P <0.001, respectively).
Conclusions: The most frequently observed clinical features of FMF (i.e., fever and abdominal pain) are both observed in patients with confirmatory and nonconfirmatory mutations, ELE and arthritis are more commonly observed in patients with confirmatory mutations.
(© 2021 Japan Pediatric Society.)