Genetic Counseling: Chromosomal Structural Rearrangements

Structural rearrangements are classified into balanced and unbalanced types. Balanced structural rearrangements mainly result from translocations (e.g., reciprocal translocation, Robertsonian translocation, and inversion), and unbalanced structural rearrangements result from deletion, duplication, insertion, ring chromosomes, and small supernumerary marker chromosomes, in addition to derivative chromosomes associated with translocations and inversion. Chromosomal variants are structural rearrangements that do not affect phenotypes or reproduction, and it is important not to confuse other structural rearrangements. Besides, it is desirable to provide medical information to help the parents understand the situation, essential points in the future of their reproductive health, and to propose psychological and social support as needed.