Objectives: This study aims to investigate a genetic panel in patients with periodic fever, aphthous stomatitis, pharyngitis, and adenitis (PFAPA) syndrome and examine its performance for an accurate differential diagnosis. Patients and methods: Between January 2021 and January 2022, a total of 104 children with PFAPA syndrome (63 males, 41 females; mean age: 4.8±2.3 years; range, 1.2 to 8.9 years) were retrospectively analyzed. Next-generation sequencing test was performed using a custom QIAGEN- QIAseq™ Targeted DNA Panel which includes six genes namely ELANE, LPIN2, MEFV, MVK, NLRP3, and TNFRSF1A. Results: Of 104 patients, 38 (36.5%) had variants in the genetic panel. The most common variants were found in the MEFV gene (n=35, 33.6%), the most frequent genotype was E148Q heterozygosity (n=16). Four and two patients were eventually diagnosed with Familial Mediterranean fever (FMF) and hyperimmunoglobulin D syndrome (HIDS), since they had confirmative biallelic pathogenic in the MEFV and MVK genes, respectively. Conclusion: A genetic panel, including MEFV and MVK genes, may be useful in patients, clinically resembling PFAPA, since they may have HIDS or FMF, but lack typical features of the exact disease. Nonetheless, we believe that distinct genetic panels should be developed for different populations.

Introduction: Chromosomal abnormalities are mostly found in 0.5–0.8% of live-born infants with developmental and morphological defects. Paracentric inversions are structural intrachromosomal rearrangements resulting in a risk of chromosomally unbalanced gametes in carriers. Case Presentation: Herein, we report a patient with dicentric rearrangement of chromosome 18 due to maternal paracentric inversion of chromosome 18. The patient was a girl, aged 3 years and 11 months. She was referred due to multiple congenital abnormalities, severe intellectual disability, and motor retardation. She had microcephaly, prominent metopic suture, synophrys, epicanthic folds, telecanthus, wide-set alae nasi, wide columella, bilateral cleft lip and palate, pectus carinatum, umbilical hernia, pes planus, and anteriorly displaced anus. She had bilateral external auditory canal stenosis and mild right-sided and moderate left-sided sensorineural hearing loss. Echocardiography showed secundum-type atrial septal defect and mild tricuspid failure. Brain magnetic resonance imaging showed only thinning of posterior areas of the corpus callosum. Chromosome analysis showed 46,XX,dic rec(18) by GTG and C banding. Dicentric chromosome was confirmed by fluorescence in situ hybridization analysis. Paternal karyotype was normal 46,XY but maternal chromosome analysis showed a paracentric inversion in chromosome 18 with 46,XX,inv(18)(q11.2?q21.3?) karyotype. Array CGH was performed on a peripheral blood sample from the patient and showed duplication at 18p11.32p11.21 and 18q11.1q11.2, and deletion at 18q21.33q23. The patient’s final karyotype is arr 18p11.32p11.21(64,847_15,102,598)×3,18q11.1q11.2(18,542,074_22,666,470)×3,18q21.33q23(59,784,364_78,010,032)×1. Discussion: To the best of our knowledge, this is the first report of a patient with dicentric chromosome 18 due to a parental paracentric inversion of chromosome 18. We present the genotype-phenotype correlation with literature review.