[1] The term mosaic (from medieval Latin musaicum, meaning "work of the Muses")[2] has been used since antiquity to refer to an artistic patchwork of ornamental stones, glass, gems, or other precious material.
[4] Novel array based techniques for screening genome-wide copy number variants and loss of heterozygosity in single cells showed that chromosome aneuploidies, uniparental disomies, segmental deletions, duplications, and amplifications frequently occur during embryogenesis.
[6] Genetic alterations involving gains or loss of entire chromosomes predominantly occur during anaphase stage of cell division.
[7] Somatic variations during embryonic development can be represented by monozygous twins since they carry different copy number profiles and epigenetic marks that keep on increasing with age.
Other factors include the loss of methylation, increasing gene expression heterogeneity correlating to genomic abnormalities,[4] and telomere shortening.
This can be due to endogenous mechanism such as homologous recombination, codon substitution, second-site suppressor mutations, DNA slippage, and mobile elements.
[12] Numerous studies demonstrated that the clonal populations might lead to loss of organismal health through the functional decline of tissue and/or the promotion of disease processes, such as cancer.
This is the reason why the aberrant clonal expansion (ACE) resulting from cancer-associated mutations are common in noncancerous tissue and accumulate with age.
A number of environmental factors, such as smoking, viral infections, and pesticide exposure, may contribute not only through mutation induction but also by modulation of clonal expansion.
With the advent of NGS, it has become increasingly clear that somatic mutations accumulate with aging in normal tissue, even in individuals who are cancer-free.
[14][15] Somatic aneuploidy such as SNVs (single-nucleotide variations) and CNVs (copy number variations) have been particularly observed and linked to brain disfunctions when arising in prenatal brain development; anyway those somatic aneuploidy have been observed in rates of 1,3-40%, potentially increasing with age and for this reason they have been proposed as a mechanism to generate normal genetic diversity among neurons.
[16] The confirmation of that hypothesis has been obtained through studies of single-cell sequencing, which allow a direct assessment of single neuronal genomes, so that a systematic characterization of somatic aneuploidies and subchromosomal CNVs of these cells is possible.
[18] Single-cell paired-end sequencing experiments found out that SLAVs are present both in neurons and glia of hippocampus and frontal cortex.
[citation needed] Since experiments showed that a half of the analyzed SLAVs lack target site duplication (TSD), another kind of L1-associated variant might occur.
The constant region (C) on the heavy chain is important in the BCR signaling and determines the type of immunoglobuline (IgA, IgD, IgE, IgG, or IgM).
[25] At Stanford, a team led by Euan Ashley demonstrated somatic mosaicism in the heart of a newborn presenting with life threatening arrhythmia.
A model combining partial and ordinary differential equations with inputs from heterologous single channel electrophysiology experiments of the genetic variant recapitulated certain aspects of the clinical presentation.