 Hence, in hindsight, the first observation of neocentromeres made by Andy Choo in 1997 was most likely an example of a Class II pericentric interstitial deletion, followed by a complex rearrangement.The neocentromere can either appear on the linear chromosome or on the ring chromosome, depending on which ever one lacks a centromere.For Class II, it is unclear when the rearrangement occurs.