We describe a young patient with typical neurofibromatosis type 1 on the basis of a mutation in the NF1 gene, who was diagnosed with a unilateral vestibular schwannoma caused by a somatic mutation in the NF2 gene. This combination has not been described before. This report highlights the requirement for ongoing surveillance regarding other manifestations of neurofibromatosis type 2 in such patients, as mosaicism cannot be ruled out. In addition to the NF1 mutation, the NF2 mutation should be considered in such cases if pre-implantation genetic diagnosis in undertaken.