What is germline mosaicism in genetics?

Germline mosaicism means that some sperm or eggs have a gene mutation that may not be present in other tissues of the body (such as the blood, which is typically used for genetic testing).

What is somatic mosaicism?

Somatic mosaicism is the accumulation of mutations in DNA sequence or copy number in cellular genomes after fertilization. Somatic mutations are present in both normal cells and in various diseases. Somatic variations have been suggested to play a major role in driving neuronal diversity and genome evolution.

What is the difference between somatic and germline?

Somatic mutations – occur in a single body cell and cannot be inherited (only tissues derived from mutated cell are affected) Germline mutations – occur in gametes and can be passed onto offspring (every cell in the entire organism will be affected)

What is the difference between somatic and germline mutations?

Germline mutations occur in sperm, eggs, and their progenitor cells and are therefore heritable. Somatic mutations occur in other cell types and cannot be inherited by offspring.

What is the difference between germline and somatic testing?

Somatic testing is done on cancer cells. It can help doctors learn more about your cancer. Germline testing is done on non-cancer cells. It can show if a genetic change is in all of your cells in your body.

How do you identify germline mosaicism?

How is germline mosaicism found? Women with germline mosaicism will not be found to be carriers via genetic carrier testing, because carrier testing is done on blood or saliva cells. Women with germline mosaicism have mutations in their egg cells, which will not show up on the blood or saliva test.

When does somatic mosaicism occur?

Somatic mosaicism occurs when the somatic cells of the body are of more than one genotype. In the more common mosaics, different genotypes arise from a single fertilized egg cell, due to mitotic errors at first or later cleavages.

Can you pass on somatic mosaicism?

If the mosaicism occurs only in a somatic cell population, the phenotypic effect will depend on the extent of the mosaic cell population; however, there would be no risk of passing on the mosaic genotype to offspring.

Are germline cells somatic?

Germ Line A germ line is the sex cells (eggs and sperm) that are used by sexually reproducing organisms to pass on genes from generation to generation. Egg and sperm cells are called germ cells, in contrast to the other cells of the body that are called somatic cells.

How common is germline mosaicism?

All women who have an affected child and no mutation found on carrier testing have a small chance to have germline mosaicism. It is not known exactly how often this happens, though some studies have suggested up to 15%.

Is Somatic mosaicism heritable?

It is inherited in an autosomal dominant manner (and is among the most common such disorders with a prevalence of 1:3000). Most cases of NF1 are caused by heterozygous loss-of-function mutations of the tumor suppressor gene encoding neurofibromin 1.

What are somatic and germline cells?

Narration. “Somatic cells” is a fairly general term which refers to essentially all the cells of the body except for the germ line; the germ line being the cells in the sexual organs that produce sperm and eggs.