Genotype/phenotype correlations in Arab patients with familial Mediterranean fever.

OBJECTIVES

To study the phenotype/genotype correlations in Arab patients with familial Mediterranean fever (FMF).

PATIENTS AND METHODS

The study was performed in a 3-year period (February 1998-February 2001). Patients were seen in the pediatric FMF clinic of Jordan University Hospital, and the diagnosis of FMF was made according to published criteria. Screening for mutations was carried out by direct sequencing of the entire coding sequence of exon 10 and its donor splice site and by restriction endonuclease testing for mutations in exon 2. A total of 278 patients with clinically positive FMF were screened.

RESULTS

Of the 278 patients, 50 (18%) had 2 mutations identified, and 76 (27%) other patients had only 1 mutation identified. The 50 patients with 2 mutations are the subject of this report. The M694V/M694V and the M694V/V726A and M694I/M694I genotypes were the most common (30%, 16%, and 14%, respectively). Three homozygous genotypes (M694V/M694V, V726A/V726A, and M694I/M694I) and 2 compound heterozygous genotypes (M694V/V726A and V726A/M680I) accounted for 78% of mutations. The difference in the mean severity score (14 +/- 2) of the M694V/M694V group and the V726A/V726A (mean severity score, 10 +/- 3) and M694I/M6941 (mean severity score, 6 +/- 1) groups was statistically significant (P =.003 and.0, respectively). The difference between the M649V/M694V group and the M694V/V726A (mean severity score, 15 +/- 2) was not statistically significant (P = 0.31).

CONCLUSIONS

The genotypes M694V/M694V and M694V/V726A have a severe clinical course in Arab patients with FMF, whereas the M694I/M694I is associated with mild disease.