The influence of genotype on disease severity and concomitant diseases in familial Mediterranean fever patients.

OBJECTIVES: To evaluate differences between the patients with familial Mediterranean fever (FMF) with homozygous (Hom), heterozygous (Het) and compound heterozygous (cHet) MEFV mutations in terms of clinical features and severity of the disease, as well as frequency of concomitant disorders, without focusing on Exon 10 mutations.

METHODS: The patients with FMF were diagnosed using the Tel-Hashomer diagnostic criteria. The presence of MEFV mutations was investigated in exons 2,3,5 and 10 by multiplex-PCR reverse hybridisation method. All the patients were questioned for the presence of concurrent disorders, and the medical records of these patients were revised retrospectively.

RESULTS: 259 unrelated patients (female: 143, male: 116; mean age: 33.5±12 years) were included in this study. Hom and Het mutations were found in 79 (31.9%) and 88 (35.6%) patients with FMF, respectively. cHet mutations were found in 68 (27.5%) FMF patients. Early onset and early diagnosis of FMF were found in Hom group compared to Het and compound Het groups. The number of the patients with a higher severity score was significantly higher in Hom group (n=40, 50.6%) than Het (n=12, 13.6%) and cHet groups (n=10, 14.7%), (p<0.0001). No significant differences were found between the groups in terms of clinical features, except for erysipelas like erythema (ELE) (Hom group: 69.6% vs. Het group 37.5%, p<0.0001). Amyloidosis and concomitant disorders were found in 22 FMF patients with Hom MEFV mutations, 16 FMF patients with heterozygous mutations, 7 FMF patients with cHet mutations.

CONCLUSIONS: While the presence of homozygous mutations creates tendency for a severe disease phenotype, the development of concomitant disorders seems to be independent of homozygous mutations.