Fused teeth, macrodontia and increased caries are characteristic features of neurofibromatosis type 1 patients with NF1 gene microdeletion.

Neurofibromatosis type 1 (NF1) is the most common genetic condition caused by NF1 gene alteration. A 1.5 Mb submicroscopic deletion encompassing the entire NF1 gene, is known to be responsible for approximately 5% of NF1 cases. Patients with NF1 deletion, compared to those with NF1 mutation tend to exhibit more severe phenotypes. To know the possible differences in oral/dental features between NF1 deletion and NF1 mutation patients, we examined four patients with NF1 deletion and three with NF1 mutation to compare their oral manifestations. Fused teeth in the mandibular anterior region were found only in the patients with deletion (2/4). Macrodontia was noted in all four patients with an NF1 deletion. Although macrodontia was also found in one patient with a mutation, it was relatively mild compared to the deletion patients. Dental caries were observed in both NF1 deletion (4/4) and mutation (2/3) patients. However, patients with NF1 deletions showed more apparently severe caries (average number of dental caries 12.8) than those with NF1 mutation (average number 5.5). Other features also noted in patients with both deletions and mutations were high-arched palate, hypodontia and malocclusion. Our study might suggest that fused teeth, macrodontia and increased dental caries are distinctive manifestations of NF1 deletion. Providing comprehensive dental care from early infancy would be very important to prevent dental caries especially in patients with NF1 deletion.