Deletion of the whole NF1 gene in a three-generation family with neurofibromatosis type 1.

BACKGROUND

Neurofibromatosis type 1 (NF1) is an autosomal dominant neurocutaneous disorder characterized by café-au-lait macules (CALMs), skinfold freckling, Lisch nodules, and neurofibromas. It is associated with heterozygous mutations in the neurofibromatosis type 1 (NF1) gene. Whole NF1 deletion has been described in some cases, but most cases are sporadic, and familial forms are extremely rare. To date, only two-generation familial forms have been described.

OBJECTIVE

To describe a whole NF1 gene deletion in a three-generation family with neurofibromatosis type 1.

METHODS

Physical examinations, laboratory tests, structural neuroimaging studies, whole-exome sequencing, and multiplex ligation-dependent probe amplification analysis were carried out.

RESULTS

All the affected individuals within this three-generation family, including the 14-year-old female proband, her 40-year-old father, and 63-year-old grandmother, exhibited such typical manifestations of NF1 as CALMs and cutaneous neurofibromas, CALMs increased in size with age. The affected subjects had more localized hyperpigmentation and CALMs within the lesion areas, mainly in the chest, abdomen, waist, and back. In addition, learning disorder was observed in the proband, and brain MRI revealed abnormal high signal lesions in the brainstem. All the affected subjects had normal birth history and had no significant past medical history. Whole-exome sequencing and subsequent multiplex ligation-dependent probe amplification analysis identified deletion of the whole NF1 gene, co-segregating with the NF1 phenotype in an autosomal dominant pattern.

CONCLUSIONS

Our findings are the first to identify whole NF1 deletion in a three-generation family with autosomal dominant NF1 and broaden the understanding of the genetic spectrum of NF1-associated NF1.