Incidental finding of a pathogenic mosaicism in the NF1 gene detected by near infrared fundus imaging - a case report.

Background: Neurofibromatosis type 1 is an autosomal dominant disorder predisposing to numerous tumors. Sporadic mutations account for half of the cases. They can occur on a mosaic pattern, which might remain undiagnosed, depending on the clinical phenotype.

Materials and methods: We carried out an extended ophthalmological assessment followed by a neurological examination as well as a cardiovascular and an orthopedic examination. The patient's DNA was drawn and next generation sequencing was used on a multigenic panel (NF1, NF2, SPRED1, LZTR1, SMARCB1, SMARCE1). A written informed consent was obtained from the patient.

Results: We report the case of a thirty-year-old male who presented for a routine ocular checkup. An incidental finding of bilateral numerous bright patchy areas was made on near infrared reflectance imaging, alongside retinal microvascular anomalies. Further questioning and examination revealed café-au-lait macules and axillary freckling, but no Lisch nodules. The patient was referred for genetic testing and a somatic mosaic mutation was found on the NF1 gene (c.4084C>T on the exon 30) with a variant allele frequency of 20%.

Conclusions: This report highlights the role of near infrared reflectance imaging in the incidental finding of choroidal alterations, which led to the diagnosis of NF1 mosaicism.