Vertical type 1 is suggestive of ‘long face syndrome’ or ‘steep mandibular plane angle’ type of class II. The functional occlusal plane is also steep associated with a palatal plane that is tipped downward. In long face individuals, who have excessive lower anterior face height, the palatal plane rotates down posteriorly, often creating a negative rather than the normal positive inclination to the true horizontal. The mandible shows an opposite, backward rotation, with an increase in the mandibular plane angle. Ref: Orthodontics: Diagnosis and Management of Malocclusion and Dentofacial Deformities, 3e, Om P. Kharbanda pdf no 2526