Chromosomal aberrations are structural modifications to chromosomes that can include deletions, duplications, translocations, and inversions. Deletions occur when a segment of a chromosome is lost. Duplications happen when a segment is repeated on a chromosome. Translocations involve the breaking off of part of one chromosome and attaching to another non-homologous chromosome. Inversions are when a segment of a chromosome is reversed in orientation. These aberrations can have genetic effects like pseudodominance or altering phenotypes depending on the genes involved.