Co-occurrence of neurofibromatosis type 1, caused by Alu insertion, and 16p13.11 microduplication

Neurofibromatosis type 1 (NF1), an autosomal dominant disorder, characterized by a spectrum of diverse neurocutaneous manifestations, is caused by heterozygous pathogenic variants in NF1 gene. While patients with NF1 often exhibit characteristic features, atypical phenotypes can arise, necessitating consideration of differential diagnoses or concurrent pathologies.

A seven-year-old boy with suspected NF1 underwent clinical evaluation. He presented hallmark café-au-lait spots, axillary freckling, and neurofibromas. Neuroimaging revealed a cranial plexiform neurofibroma. Additionally, he exhibited attention-deficit hyperactivity disorder and developmental delay. Genetic testing identified an Alu insertion variant within the NF1 gene, and subsequent array comparative genomic hybridization detected a 16p13.11 duplication.

This case underscores the intricate molecular bases of NF1 by identifying a rare Alu insertion variant. The patient's neurocognitive challenges and dysmorphic features prompted exploration of a potential overlapping genetic condition. Coexisting genetic disorders have been documented in NF1 patients, emphasizing the necessity of discerning atypical manifestations. The observed 16p13.11 duplication likely contributes to the patient's phenotype, enhancing the precision of diagnosis, prognosis, and genetic counseling.