Keratitis fugax hereditaria ‐ useful to consider when you have a child with non‐specific corneal findings and symptoms

Purpose: To report clinical findings in children diagnosed with the autosomal dominant periodic corneal autoinflammation, keratitis fugax hereditaria (KFH, MIM 148200), and to highlight its geographical distribution. Methods: Patients were clinically examined in the Helsinki University Hospital between February 4, 2006, and December 31, 2021, and genetically verified to be carriers of the c.61G > C (rs200154873) variant in NLRP3 by Sanger sequencing. Variant allele frequencies were determined from Genome Aggregation Database (gnomAD) version 2.1.1. Results: The data consist of 10 children from 8 families; 6 boys and 4 girls. Age of onset varied from 3 to 14 (median, 8) years. Patients had typical KFH symptoms: eye pain, photophobia, conjunctival injection, and foreign body sensation. Five patients had corneal oval opacities, and 3 had a mild anterior chamber reaction. Seven were correctly diagnosed at the first visit based on family history. The remaining three children were diagnosed 1, 3, and 8 years after the first visit. Initial diagnoses were anterior uveitis, corneal erosion, and herpetic keratitis. Additionally, epithelial recurrent erosion dystrophy (ERED) or subepithelial mucinous corneal dystrophy (SMCD) had been suspected. Geographically, KFH concentrates to the bilingual Swedish‐speaking coastal areas of Finland. Allele frequencies are 0.014% in Finland, and 0.011% in Sweden, based on gnomAD. Conclusions: Scandinavian ophthalmologists should be aware of the possibility of KFH in case of suspected anterior uveitis, herpetic keratitis, or recurrent corneal erosion in children. Symptoms of paediatric KFH patients are equal to those in adults, but the typical corneal opacity still might recover between the attacks.