Somatic mosaicism

Somatic mosaicism is the presence within one organism of cell populations with different genetic variants arising after fertilization. Its effects depend on when mutations occur and which tissues inherit them.

Postzygotic mutation: A genetic change that occurs after fertilization in an embryo or later in an organism’s cells. These mutations create genetically distinct lineages within one organism.
Mosaic variegated aneuploidy syndrome: A rare disorder marked by chromosome-number abnormalities in a fraction of cells and increased cancer risk. It is a named disorder caused by chromosomal mosaicism.
Germline mosaicism: The presence of a genetic variant in a subset of a person’s egg or sperm cells. Unlike somatic-only mosaicism, it can transmit a variant to offspring.
Deep sequencing: DNA sequencing with unusually high read coverage across targeted genomic regions. Greater coverage can detect low-frequency mosaic variants missed by routine testing.
Clonal expansion: The growth of a population of cells descended from a single ancestral cell. A mutated lineage can become a large, detectable fraction of a tissue.
McCune–Albright syndrome: A disorder involving fibrous bone lesions, café-au-lait pigmentation, and endocrine abnormalities from postzygotic GNAS variants. Its distribution of symptoms reflects where the mutant cell lineage developed.
Chimerism: The coexistence in one organism of cell populations derived from different zygotes. Mosaic cell lineages arise within one zygote, while chimeric lineages have separate origins.
Tissue-specific mosaicism: Genetic mosaicism confined to particular tissues or cell types. A variant’s tissue distribution often determines symptoms and diagnostic visibility.
Developmental biology: The study of how organisms grow and develop from fertilization to maturity. Development determines which cell lineages inherit each mutation.
Proteus syndrome: A rare overgrowth disorder usually caused by a postzygotic activating variant in AKT1. The mosaic variant produces patchy, asymmetric tissue overgrowth.

Linked from 5 pages