Final answer:
The structural aberration known as nondisjunction leads to the loss of a chromosome, resulting in a condition like monosomy, which can be identified in a karyogram as a chromosome number disorder.
Step-by-step explanation:
The type of structural aberration that can lead to the loss of a chromosome is known as nondisjunction. This occurs when pairs of homologous chromosomes or sister chromatids fail to separate during meiosis. Specifically, if homologous chromosomes do not separate during meiosis I, or if sister chromatids do not separate during meiosis II, the result can be one or more gametes lacking that particular chromosome, leading to monosomy, which is the loss of a chromosome. This can cause a variety of chromosome number disorders, which on a karyogram are identifiable as a change in the normal number of chromosomes.