While a number of diagnostic criteria for NF2 have been proposed, the Manchester criteria (2005) have become the most widely used.22 A definite diagnosis is made by (1) the presence of bilateral VS or (2) a history of a first-degree family relative with NF2 and the development of either a unilateral VS or least 2 of the following conditions known to be associated with NF2: meningioma, glioma, neurofibroma, schwannoma, or posterior subcapsular lenticular opacities. This evidence concerns the gene NF2 and schwannoma.