Chromosome structure mutations are alterations that affect whole chromosomes and whole genes rather than just individual nucleotides.

These mutations result from errors in cell division that cause a section of a chromosome to break off, be duplicated or move onto another chromosome.

Chromosome structure mutations can be one of four types:

• deletion is where a section of a chromosome is removed.
• translocation is where a section of a chromosome is added to another chromosome that is not its homologous partner.
• inversion is where a section of a chromosome is reversed.
• duplication occurs when a section of a chromosome is added from its homologous partner.

Chromosome mutations are often lethal as the chromosome structure is altered.