Is PFAPA syndrome really a sporadic disorder or is it genetic?

A Potential Partnership between Genetics and the Oral Microbiome in Children Displaying Periodic Fever/Aphthosis/Pharyngitis/Adenitis Syndrome

Periodic fever/aphthosis/pharyngitis/adenitis (PFAPA) syndrome was initially described in a small cohort of American children [...].

NLRP3 gene variants and serum NLRP3 levels in periodic fever, aphthous stomatitis, pharyngitis, and adenitis (PFAPA) syndrome

OBJECTIVES

Although most of the autoinfammatory disorders have a confirmed genetic cause, periodic fever, aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) syndrome still has an unknown genetic background. However, familial cases of PFAPA syndrome have been reported suggesting a genetic its basis. PFAPA syndrome may also be considered an infammasome disorder as variants in infammasome-associated genes such as CARD8, NLRP3, and MEFV have been reported to contribute to the disease.

METHODS

Polymerase chain reaction (PCR)/Sanger sequencing analysis was performed for the detection of the variations in 71 PFAPA patients and 71 healthy controls. NLRP3 concentrations in serum were measured in 71 PFAPA patients and 71 healthy controls.

RESULTS

No statistically significant differences were observed in the allele or genotype frequencies of the NLRP3 polymorphisms between the controls and patients (P > 0.05). We found no significant differences for NLRP3 serum levels between PFAPA patients and controls (p > 0.05). Mutations in the MEFV gene were detected in 32.5% of our patients (13/40).

CONCLUSIONS

It seems that the synergistic effect of different genes plays a role in the formation of PFAPA syndrome. For this reason, it may be useful to examine the presence of mutations in genes such as NLRP3, MEFV, and CARD8 together while investigating the genetics of PFAPA syndrome. Key points • Familial cases of PFAPA syndrome have been reported suggesting a genetic basis for this syndrome. • Elevated serum or plasma levels of IL-1β, IL-6, and IL-18 have been demonstrated during PFAPA flares in several studies. • It seems that the synergistic effect of different genes plays a role in the formation of PFAPA syndrome.

PFAPA Syndrome: Clinical, Laboratory and Therapeutic Features in a Single-Centre Cohort

Objective

The aim of this study is to describe a group of Romanian children with periodic fever, aphthous stomatitis, pharyngitis and cervical adenitis (PFAPA) syndrome.

Materials

This consisted of 39 children diagnosed with PFAPA syndrome according to Thomas’ criteria (eight patients with an age at diagnosis <1 year and 31 patients with an age at diagnosis >1 year).

Methods

Retrospective analysis of the patients with PFAPA syndrome was focused on clinical features, laboratory findings and therapeutic methods. Comparison between the two groups divided by age at onset was also investigated.

Results

Median age at onset was 1.58 years, and median age at diagnosis was 2.97 years. The mean interval between episodes was 35.5 days and the mean duration per febrile episode was 4.1 days. The median diagnosis delay was 2.42 years. The patients presented pharyngitis (100%), adenitis (94.8%) and aphthous lesions (66.7%). The frequency of febrile attacks was higher in children with an age at diagnosis under 1 year (p = 0.0287). Younger age was associated with the presence of aphthae. The mean value of C-reactive protein (CRP) was 7.9mg/dl and the mean value of leucocytes was 14,839/mm³. In 95% of patients given oral corticosteroids, remission of symptoms was reported within 24 h. In three patients, tonsillectomy was performed with complete remission of the disease.

Conclusion

We present a cohort of children with PFAPA syndrome, with clinical and laboratory features similar to those described in the literature. Febrile attacks had a higher incidence in children with younger age at the onset of the disease. The patients had a favorable response to corticosteroids.

Towards better diagnostic criteria for periodic fever, aphthous stomatitis, pharyngitis and adenitis syndrome

AIM

Periodic fever, aphthous stomatitis, pharyngitis and cervical adenitis (PFAPA) syndrome is the most common cause of a periodic fever in childhood. The exact pathogenesis and the aetiology of PFAPA are still unknown.

METHODS

We conducted a non-systematic review of published articles about PFAPA syndrome and summarised the evidence for diagnostic criteria and treatment options for PFAPA.

RESULTS

The first proposed diagnostic criteria for PFAPA, in addition to periodic fever, included aphthous stomatitis, pharyngitis or cervical lymphadenitis in children younger than five years at the beginning of the symptoms. C-reactive protein (CRP) levels and leucocyte counts increase in most patients during episodes. Recent research reveals that tonsillectomy provides an immediate and long-lasting cure for PFAPA, even in the absence of classic criteria of aphthous stomatitis, pharyngitis or cervical adenitis and in children older than five years.

CONCLUSION

We suggest that PFAPA can be diagnosed in children with at least five regularly occurring fever episodes without any other explanation, even in the absence of aphthous stomatitis, pharyngitis or cervical lymphadenitis and also in children older than five years.

Rare missense variants in the ALPK1 gene may predispose to periodic fever, aphthous stomatitis, pharyngitis and adenitis (PFAPA) syndrome

PFAPA is an autoinflammatory syndrome characterized by periodic fever, aphthous stomatitis, sterile pharingitis, and adenitis, with an onset usually before the age of five. While the condition is most commonly sporadic, a few cases are familial and are usually compatible with an autosomal dominant (AD) transmission pattern, with reduced penetrance in some pedigrees. We performed exome analysis in a family where PFAPA was present in three relatives in two generations showing apparent AD segregation, identifying several rare and/or novel heterozygous variants in genes involved in the autoinflammatory pathway. Following segregation analysis of candidate variants, only one, c. 2770T>C p.(S924P) in the ALPK1 gene, was found to be consistently present in affected family members. ALPK1 is broadly expressed in different tissues and its protein is the intracellular kinase activated by the bacterial ADP-heptose bisphosphate that phosphorylates and activates TRAF-Interacting protein with Forkhead-Associated domain (TIFA) and triggers the immediate response to Gram-negative bacterial invasion. Sequencing analysis of 13 additional sporadic cases and 10 familial PFAPA cases identified two additional heterozygous missense variants c.1024G>C p.(D342H) and c.710C>T p.(T237M) in two sporadic patients, suggesting that rare variants in ALPK1 may represent a predisposing factor for recurrent periodic fever in a pediatric population.

PFAPA Syndrome in a Population with Endemic Familial Mediterranean Fever

We reviewed the medical records of patients with periodic fever, aphthosis, pharyngitis, and adenitis (PFAPA) to investigate the clinical course, treatment response, and association with MEFV gene mutation. Familial Mediterranean fever should be considered in patients with PFAPA who do not respond to adenotonsillectomy.

Analysis of the genetic basis of periodic fever with aphthous stomatitis, pharyngitis, and cervical adenitis (PFAPA) syndrome

PFAPA syndrome is the most common autoinflammatory syndrome in children from Western countries. In spite of its strong familial clustering, its genetic basis and inheritance pattern are still unknown. We performed a comprehensive genetic study on 68 individuals from 14 families. Linkage analysis suggested a susceptibility locus on chromosome 8, but direct molecular sequencing did not support this initial statistical finding. Exome sequencing revealed the absence of any gene that was mutated in all patients. Exhaustive screening of genes involved in other autoinflammatory syndromes or encoding components of the human inflammasome showed no DNA variants that could be linked to PFAPA molecular pathology. Among these, the previously-reported missense mutation V198M in the NLRP3 gene was clearly shown not to co-segregate with PFAPA. Our results on this relatively large cohort indicate that PFAPA syndrome is unlikely to be a monogenic condition. Moreover, none of the several genes known to be involved in inflammation or in autoinflammatory disorders seem to be relevant, alone, to its etiology, suggesting that PFAPA results from oligogenic or complex inheritance of variants in multiple disease genes and/or non-genetic factors.

Clinical features and genetic background of the periodic Fever syndrome with aphthous stomatitis, pharyngitis, and adenitis: a single center longitudinal study of 81 patients

PFAPA syndrome is the most common autoinflammatory disorder in childhood with unknown etiology. The aim of our study was clinical evaluation of PFAPA patients from a single tertiary care center and to determine whether variations of AIM2, MEFV, NLRP3, and MVK genes are involved in PFAPA pathogenesis. Clinical and laboratory data of consecutive patients with PFAPA syndrome followed up at the University Children's Hospital, Ljubljana, were collected from 2008 to 2014. All four genes were PCR amplified and directly sequenced. Eighty-one patients fulfilled criteria for PFAPA syndrome, 50 (63%) boys and 31 (37%) girls, with mean age at disease onset of 2.1 ± 1.5 years. Adenitis, pharyngitis, and aphthae were present in 94%, 98%, and 56%, respectively. Family history of recurrent fevers in childhood was positive in 78%. Nineteen variants were found in 17/62 (27%) patients, 4 different variants in NLRP3 gene in 13 patients, and 6 different variants in MEFV gene in 5 patients, and 2 patients had 2 different variants. No variants of clinical significance were found in MVK and AIM2 genes. Our data suggest that PFAPA could be the result of multiple low-penetrant variants in different genes in combination with epigenetic and environmental factors leading to uniform clinical picture.

SPAG7 is a candidate gene for the periodic fever, aphthous stomatitis, pharyngitis and adenopathy (PFAPA) syndrome

Periodic fever, aphthous stomatitis, pharyngitis and adenopathy (PFAPA) syndrome is an auto-inflammatory disease for which a genetic basis has been postulated. Nevertheless, in contrast to the other periodic fever syndromes, no candidate genes have yet been identified. By cloning, following long insert size paired-end sequencing, of a de novo chromosomal translocation t(10;17)(q11.2;p13) in a patient with typical PFAPA syndrome lacking mutations in genes associated with other periodic fever syndromes we identified SPAG7 as a candidate gene for PFAPA. SPAG7 protein is expressed in tissues affected by PFAPA and has been functionally linked to antiviral and inflammatory responses. Haploinsufficiency of SPAG7 due to a microdeletion at the translocation breakpoint leading to loss of exons 2-7 from one allele was associated with PFAPA in the index. Sequence analyses of SPAG7 in additional patients with PFAPA point to genetic heterogeneity or alternative mechanisms of SPAG7 deregulation, such as somatic or epigenetic changes.