CDKN2A and plexiform neurofibroma: The genomes of MPNSTs are characterized by a large number of recurrent DNA copy number aberrations (CNAs).7, 8, 9 The tumour suppressor gene CDKN2A is the target of frequent deletions on chromosome arm 9p.10, 11, 12, 13 This event occurs early in MPNST development, and has been found also in benign and atypical neurofibromas.