The utility of genetic testing in the diagnosis of familial Mediterranean fever.

In their otherwise excellent review of familial Mediterranean fever (FMF), Lidar and Livneh argue against testing for Mediterranean fever gene (MEFV) mutations both in their diagnostic algorithm and in their subsequent discussion of the case. Although the clinical criteria for FMF are highly sensitive and specific, incorporation of genetic testing will not only confirm the diagnosis but adds valuable information about prognosis as the frequency of secondary amyloidosis varies between genotypes. Moreover, identifying the MEFV mutations in affected cases is crucial if genetic testing is to be offered to other family members. The FMF phenotype can show considerable intrafamilial variation and siblings of affected cases could be asymptomatic but still develop amyloidosis (type II FMF) which is potentially avoidable if treatment is instigated in a timely manner. Finally, mutation analysis for the common FMF mutations is inexpensive and readily l E T T E r T o T H E E d i T o r