Loss of heterozygosity

An example of loss of heterozygosity over time, in bottlenecking population. Different alleles painted in different colors. A diploid population of 10 individuals, that bottlenecked down to three individuals repeatedly, resulted in all individuals homozygous.

In genetics, loss of heterozygosity (LOH) is a type of genetic abnormality in diploid organisms in which one copy of an entire gene and its surrounding chromosomal region are lost.[1] Since diploid cells have two copies of their genes, one from each parent, a single copy of the lost gene still remains when this happens, but any heterozygosity (slight differences between the versions of the gene inherited from each parent) is no longer present.

  1. ^ [Association of the autoimmune diseases scleroderma with an immunologic response to cancer,] Christine G. Joseph et al., Science, 343:152 (10 January 2014)