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A survey of phenotype II in familial Mediterranean fever
M Melikoğlu1, H Ozdoğan, C Korkmaz
1Department of Rheumatology, Cerrahpaşa Medical School, University of Istanbul, Istanbul, Turkey.
Objective:
Phenotype II in familial Mediterranean fever (FMF) is the onset of amyloidosis before the onset of FMF with its typical attacks, or as an isolated finding in a member of an FMF family. Its presence was investigated by looking for proteinuria among the asymptomatic relatives of patients with FMF complicated by amyloidosis and among the asymptomatic relatives of patients with juvenile chronic arthritis (JCA) complicated by amyloidosis, used as controls.
Methods:
The relatives of the index patients (13 with FMF and amyloidosis) and controls (6 with JCA and amyloidosis) were screened for proteinuria. Rectal biopsies were performed when proteinuria was significant (>/=300 mg/d).
Results:
461 relatives were screened in the FMF group and 269 among the controls. Two of the FMF relatives and one JCA relative had no symptoms of FMF but had significant proteinuria. Rectal biopsy for amyloidosis was negative in all instances of significant proteinuria.
Conclusion:
Phenotype II is uncommon among the relatives of patients with FMF and amyloidosis.
Insights
Phenotype II in familial Mediterranean fever (FMF) is rare. Researchers screened FMF relatives for amyloidosis, finding it uncommon even in those with proteinuria, suggesting Phenotype II is infrequent in FMF families.
Area of Science:
- Rheumatology
- Genetics
- Nephrology
Background:
- Familial Mediterranean fever (FMF) is a genetic autoinflammatory disease.
- Phenotype II FMF involves amyloidosis preceding typical FMF symptoms or occurring in isolation within FMF families.
- Amyloidosis, a complication of FMF, can lead to organ damage.
Purpose of the Study:
- To investigate the prevalence of Phenotype II in familial Mediterranean fever (FMF).
- To screen asymptomatic relatives of FMF patients with amyloidosis for early signs of the condition.
- To use asymptomatic relatives of juvenile chronic arthritis (JCA) patients with amyloidosis as controls.
Main Methods:
- Screening 461 asymptomatic relatives of FMF patients and 269 asymptomatic relatives of JCA patients for proteinuria.
- Performing rectal biopsies for amyloidosis in cases with significant proteinuria (>=300 mg/d).
Main Results:
- Two relatives in the FMF group and one in the JCA control group exhibited significant proteinuria without FMF symptoms.
- Amyloidosis was not detected via rectal biopsy in any individuals with significant proteinuria.
- The screening identified a low incidence of potential Phenotype II indicators.
Conclusions:
- Phenotype II appears to be an uncommon occurrence among relatives of FMF patients with amyloidosis.
- The study suggests that proteinuria in asymptomatic relatives does not necessarily indicate Phenotype II.
- Further research may be needed to fully understand the spectrum of FMF Phenotype II.