CDKN2A and dysplasia: Similarly, fluorescence in situ hybridization mapping by Brankley et al. demonstrated that CDKN2A loss (9p21) was the earliest and most frequent alteration, observed in 47% of areas with intestinal metaplasia (IM) and significantly more common in IM than in areas with dysplasia or adenocarcinoma (p < 0.0001).