Whole Genome Sequencing (WGS) or DNA chips with a high density are able to detect structural variation in the DNA of individual animals. It means that pieces of minimal 50 base pairs are lost, doubled, added or replaced in the genome. This might have happened in an unbalanced way in cases of CNV’s: Copy Number Variants. They can be duplicated, deleted or inserted. Or it are inversions or translocations, the result of a balanced happening in the genome. The different possibilities are illustrated in the figure below (derived from https://doi.org/10.1038/s10038-020-00838-1
It is useful to detect structural variants, because through their lengths they may influence the expression of genes. The expression can be enhanced, depressed or changed with positive, negative or neutral effects. Genes for immune functions may profit from duplications. Embryonic mortality or malformations are often caused by deletions.