Search results
Results from the WOW.Com Content Network
The remaining copy of the tumor suppressor gene can be inactivated by a point mutation or via other mechanisms, resulting in a loss of heterozygosity event, and leaving no tumor suppressor gene to protect the body. Loss of heterozygosity does not imply a homozygous state (which would require the presence of two identical alleles in the cell).
In population genetics, F-statistics (also known as fixation indices) describe the statistically expected level of heterozygosity in a population; more specifically the expected degree of (usually) a reduction in heterozygosity when compared to Hardy–Weinberg expectation.
SNPs can also be used to study genetic abnormalities in cancer. For example, SNP arrays can be used to study loss of heterozygosity (LOH). LOH occurs when one allele of a gene is mutated in a deleterious way and the normally-functioning allele is lost. LOH occurs commonly in oncogenesis.
Usually the population statistic used to define effective population size is heterozygosity, but others can be used. [ 7 ] Fixation rates can easily be modeled as well to see how long it takes for a gene to become fixed with varying population sizes and generations.
The two-hit hypothesis, also known as the Knudson hypothesis, is the hypothesis that most tumor suppressor genes require both alleles to be inactivated, either through mutations or through epigenetic silencing, to cause a phenotypic change. [1]
In one study, classic oligodendrogliomas showed 1p loss in 35 of 42 (83%) cases, 19q loss in 28 of 39 (72%), and these were combined in 27 of 39 (69%) cases; there was no significant difference in 1p/19q loss of heterozygosity status between low-grade and anaplastic oligodendroglioma.
About 3,000 human genes cannot tolerate loss of one of the two alleles. [1] An example of this is seen in the case of Williams syndrome, a neurodevelopmental disorder caused by the haploinsufficiency of genes at 7q11.23. The haploinsufficiency is caused by the copy-number variation (CNV) of 28 genes led by the deletion of ~1.6 Mb. These dosage ...
Although few imprinted genes have been identified, uniparental inheritance of an imprinted gene can result in the loss of gene function, which can lead to delayed development, intellectual disability, or other medical problems. [citation needed] The most well-known conditions include Prader–Willi syndrome and Angelman syndrome.