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Background: Neurofibromatosis type 1 (NF1) is an autosomal dominant neurocutaneous disorder, characterized by multiple café-aulait macules, axillary and inguinal freckling, tumors of the nervous system, and iris hamartomas. More than 3,100 different pathogenic variants have been reported in the NF1 gene, including missense, nonsense, frameshift, in-frame, splicing, and large deletions. Aims: To determine the NF1 mutational spectrum in patients with NF1 from the Republic of North Macedonia. Study Design: A cohort study. Methods: Molecular analyses included reverse transcription and cDNA sequencing of the NF1 gene and next-generation sequencing using the TruSight Cancer panel, along with the multiple ligation probe amplification method to detect single nucleotide variants and copy number variations. Direct DNA sequencing was also used for the family member analysis. Results: Our 9-year study of patients suspected of having NF1 in the Republic of North Macedonia encompassed molecular characterization of 30 cases of the disease. We identified 28 unique pathogenic NF1 variants (NM_001042492.3), of which ten were novel: c.208delA; c.341_364del; c.1480_1481delTT; c.2325+1G>C; c.2495_2496dupAC; c.2533_2541del; c.4517delC; c.5844C>G; c.6971delA; c.7605_7606delGAinsAT. In addition to the variant spectrum analysis, our research revealed two positive genotypephenotype correlations. One between the clinical manifestation of cognitive impairment and gross deletions in the NF1 gene, and the other between cognitive impairment and truncating variants located in the RAS-GAP functional domain. Conclusion: This is the first study of NF1 patients in the Republic of North Macedonia, and it contributes ten novel variants to the global spectrum of pathogenic NF1 variants. It also corroborates the crucial importance of NF1 genetic testing for a prompt and precise diagnosis, particularly in younger patients. [ABSTRACT FROM AUTHOR]

Background: Neurofibromatosis type 1 (NF1) is a common autosomal dominant genetic disorder with an extremely variable phenotype. In childhood NF1 can be associated with optic glioma and central precocious puberty; the latter is more common when the optic chiasm is affected. The mutational spectrum of the NF1 gene is wide and complex; R681X is a rare severe mutation of the NF1 gene known to cause truncation of neurofibromin, with only ten reported cases in the literature so far. Case presentation: We describe a girl with NF1 associated with early central precocious puberty appearing at 2.5 years of age and optic glioma affecting the optic chiasm as seen on magnetic resonance imaging (MRI). Genetic analysis confirmed the presence of R681X. Therapy with a gonadotropin-releasing hormone agonist was instituted with good response to therapy. The lesions on MRI were stable and no significant vision impairment was present during the 6 years of follow-up. Conclusion: Of the ten reported cases of NF1 due to R681X, one has presented with optic glioma and none with precocious puberty. Thus, to our knowledge, this is the first reported case of this mutation presenting with precocious puberty. We believe that this is a contribution to the few reports on the phenotype of this mutation and to the future elucidation of genotype-phenotype correlations of this disease. [ABSTRACT FROM AUTHOR]