Structural and Mechanistic Diversity of Constitutional Chromoanagenesis.

Chromoanagenesis correspond to cataclysmic complex chromosomal rearrangements. They are separated into three categories-chromothripsis, chromoanasynthesis, and chromoplexy-based, among others, on the number of breakpoints, the copy number state, and the molecular signature at junctions. However, criteria may be overlapping or may be difficult to evaluate, leading to blurred border between the three types of chromoanagenesis and even other complex chromosomal rearrangements. Moreover, observations of constitutional chromoanagenesis show increasing complexity, often surpassing the current definitions.We will discuss the difficulty to classify chromoanagenesis and we will present examples of atypical complex rearrangements that question the established models of chromoanagenesis.