Genetic characterization of a Chinese cohort of suspected pediatric NF1 patients: a large-scale study using optimized...

Neurofibromatosis type 1 (NF1) is a common autosomal dominant disorder with broad clinical variability, making diagnosis in pediatric patients particularly challenging due to age-dependent penetrance and variable expressivity. In this study, we analyzed 536 unrelated Chinese children with clinical suspicion of NF1 using optimized whole-exome sequencing (WES) enhanced by targeted probe enrichment and exon-level copy number variation (CNV) analysis to investigate the molecular etiology and mutation spectrum. Pathogenic or likely pathogenic variants were identified in 288 patients (53.7%), including 271 with variants in the NF1 gene. These consisted of 197 distinct small sequence variants (SNVs) and 25 CNVs, of which 19 were large multigenic deletions, and 6 were intragenic. Notably, 62 of the NF1 SNVs were novel. The incorporation of exon-level CNV analysis and probe enrichment improved the diagnostic yield by 9.2% and 2.2%, respectively. Seven patients were found to have dual diagnoses involving NF1 and other genetic disorders, including six novel combinations. In addition, 17 were diagnosed with non-NF1 conditions such as RASopathies and cancer predisposition syndromes. Our findings highlight the value of optimized WES strategies in improving diagnostic accuracy and yield, particularly for pediatric patients with atypical clinical presentations. This study represents one of the most comprehensive assessments of NF1 molecular diagnostics in a Chinese pediatric population.