The mechanism of chromosomal mutation may vary depending on the type of mutation. 

The chromosomal structure may undergo a change due to several different accidents or mistakes that can occur during nuclear organization. Additionally, nucleases may also digest chromosome sections, resulting in the loss of these sections. 

Abnormal pairing or a lag during the cell cycle can change the number of chromosomes. Chromosomes may be added or lost if the paired chromosomes in some cells do not get separated during anaphase. 

The type and mechanism of mutation impacts the overall effect of the mutation.