A recent retrospective cohort study of 169 pediatric patients in a Palestinian referral center reveals that 18.9% of children with an Familial Mediterranean Fever (FMF)-compatible phenotype also meet the clinical classification criteria for periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) syndrome, highlighting complex clinical overlap in regions where MEFV genetic variants are frequent.
In Plain English: The Clinical Takeaway
- Overlapping Symptoms: Children in high-prevalence regions can present with clinical signs of both periodic fever syndromes simultaneously, making exact diagnosis challenging for pediatricians.
- Genetic Testing Disparities: Routine genetic screening for MEFV variants was less frequently available in patients displaying PFAPA-compatible features compared to those presenting with an FMF-only phenotype.
- No Causal Link Established: The study demonstrates phenotypic overlap but does not prove that the two conditions share a single underlying biological cause or exist as a unified disease.
Overlapping Phenotypes in Palestinian Pediatric Cohort
Familial Mediterranean fever and PFAPA syndrome frequently share clinical manifestations that complicate diagnostic accuracy. Researchers evaluated a retrospective two-center cohort consisting of 169 pediatric patients aged ≤ 18 years. These patients were initially classified with an FMF-compatible phenotype using the Eurofever/PRINTO classification framework. Following this baseline classification, clinicians assessed the cohort for PFAPA-compatible features using corresponding clinical classification criteria.
Out of the 169 total patients evaluated, 32 children—representing 18.9% of the cohort—additionally fulfilled the clinical classification criteria for PFAPA. Genetic analyses focusing on the MEFV gene were restricted to the subset of 143 patients who had available testing data. Among this genetically tested group, the M694V variant emerged as the most frequently recorded mutation, appearing in 84 patients or 58.7% of the tested population.
Discrepancies in MEFV Genetic Testing Availability
Access to genetic diagnostics varied markedly between patient subgroups within the referral cohort. MEFV genetic testing data was accessible for 124 out of 137 patients classified with an FMF-only phenotype, representing a 90.5% testing rate. Conversely, testing was documented in only 19 out of 32 patients—or 59.4%—who displayed PFAPA-compatible features alongside their FMF phenotype.
Among the 19 genetically tested patients who met PFAPA classification criteria, 10 were recorded as heterozygous, meaning they carried a single mutated gene copy. Within this heterozygous subgroup, the E148Q variant pattern proved to be the most frequent. Study authors noted that clinical manifestations incorporated into the PFAPA classification algorithm were interpreted descriptively rather than treated as independent between-group associations.
| Phenotype Subgroup | Total Patients | MEFV Tested | Testing Rate (%) |
|---|---|---|---|
| FMF-Only Phenotype | 137 | 124 | 90.5% |
| PFAPA-Compatible Features | 32 | 19 | 59.4% |
| Total Cohort | 169 | 143 | 84.6% |
Clinical Interpretation and Diagnostic Limitations
The findings demonstrate clear clinical overlap between FMF and PFAPA presentations in pediatric populations residing in areas with high MEFV variant frequencies. However, the data do not establish the coexistence of two independent diseases or confirm a definitive causal genotype-phenotype relationship. Researchers emphasize that unequal availability of genetic testing and the inherent limitations of retrospective phenotypic classification warrant cautious interpretation of the results by medical professionals.
References
- Clinical and MEFV variant characteristics of pediatric patients with an FMF-compatible phenotype and PFAPA-compatible features in a Palestinian referral cohort.
- Eurofever/PRINTO classification framework for hereditary autoinflammatory syndromes.
