Somatic Mutation

Context: The ‘Somatic Mosaicism across Human Tissues’ (SMaHT) Network is exploring somatic mutation’s significance, promoting insights into human biology and disease management through research.

Biological Terms 

Genome The entire set of genetic material in an organism. It includes both the coding sequences (genes) and non-coding regions of DNA.
Human Genome The complete set of genetic material (DNA) present in a human cell. It contains all the instructions necessary for the growth, development, functioning, and maintenance of a human being.
Deoxyribonucleic Acid (DNA)The molecule that carries genetic information in cells. It consists of a double-stranded helical structure made up of nucleotide units.HT7FcAbgr1Hz7MFZAt5kUGKSNt1Ygsd 2hJq9ga5alp6pw1ON9tocT0K1Qq w3KVpzdoaphLijZxnTuZDLddvXFDW3Dbp4bcwRSU1eJOeIAWIYA3WqC3P eVBr0DESD7x6cAZlB9taolLe4h r j Q
Chromosomes Thread-like structures made of DNA and proteins found in the nucleus of cells. They carry genetic information in the form of genes. In humans, there are 23 pairs of chromosomes (46 individual chromosomes), with one chromosome from each pair inherited from each parent.Ou0CQxjO RQ0IBocoGEiSZsFmo66BdH1cdA2yNiUiRNc sw vvDbvAXZdYysTcyP0euDk3honMsAe736BAyK OmfPjZF5BnNFkq7WRPCbnIosO9PvatOOpwvG2ykc IlBf2a19nUBjmvGyClJ8YjLg
Somatic CellsCells in the body other than sperm and egg cells (which are called germ cells). In humans, somatic cells are diploid, meaning they contain two sets of chromosomes, one inherited from each parent. DNA mutations in somatic cells can affect an individual, but they cannot be passed on to their offspring.q0 PInTl0faWLP BEPsoL4R28e9elDrZs9w9xrKycspEjSvuaj4VSFv3k7hgzNedqfRnCTx8Elgt oIT4UuyO4ZFNFcr7MvSG7c4 u4Oapd4A9 mGEmfbucTE4UukzYX MD6lvIDQrIDoKuc3wAz8g
Germ Cells Cells that give rise to the reproductive cells of sexually reproducing organisms – known as gametes – through a process called gametogenesis. In animals, the reproductive male gametes are sperm cells and the female gametes the oocytes.
Proofreading The process by which enzymes detect and correct errors (mutations) that occur during DNA replication, ensuring the accuracy of DNA copying.v tmgM41K8EySE59Hmp3M4t4 RexFNIPbJOZwC9DJ ce1WN5n3tFPHBzpjvEJwNVFEBD0dX1ZUeu5sghynmXWynt1Jav7OZ
Turnover Turnover is the replacement of old cells with new ones.
Mutation A change in the DNA sequence of a gene or chromosome. Example: Single nucleotide changes (point mutations), deletions, insertions.UWsz1knpjSnujdvyy5Bf1mHeRoghWXynC94DYNP N0pMjD2GhIl7P6I3r2UecpuqKo9EHvLTyWBUoSo1xjWPb3urQNaIAHZXECxA0mPC T
Somatic Genetic Mutation A mutation that occurs in the DNA of somatic cells (body cells) after birth. These mutations are not passed on to offspring. Example: Skin cells acquiring mutations due to UV radiation exposure.albPkwjiTwyKLn830SNNG37sewJj2pNOdy3LKnXnPxJw8oyv1N3 86E18Np8qo7di0S L 3Ggajg96g2Os9uXVJRcnjvtW
Driver Mutation A mutation that provides a growth advantage to a cell, often contributing to the development of diseases like cancer.
Genetic Variants Differences in the DNA sequence among individuals of the same species. These can include single nucleotide polymorphisms (SNPs) or larger structural variations.
Immune Cells Cells of the immune system that defend the body against pathogens. Examples include B cells and T cells.
Genetic diseases Disorders caused by mutations in an individual’s DNA. Example: Cystic fibrosis caused by mutations in the CFTR gene.
Mutation SignaturesDistinctive patterns of genetic variations associated with specific types of cancer or genetic diseases.
MicrofluidicsA technology that manipulates small amounts of fluids at a microscopic scale.
Cancer A group of diseases characterized by uncontrolled cell growth and division.H fkZESqgWWOMEgzJaNkEDKNVmoTrqBSNuchsjDBdYwMkbWuvbcgBbLvGrQqFYGEhx2VeOhd6mrcn9tT1UpQMCqz6D2IKO7fG5YJg76KtddOrDxikP a5j7s bRAeV dr8JR6Zkg
Somatic MosaicismThe presence of different genetic variants in different cells of the same individual.

Somatic Genetic Mutations

  • When cells divide, the DNA is copied with extremely high accuracy because of the proteins that proofread and correct errors in the DNA. 
  • But despite this mechanism, various studies have estimated that there is still an error rate of 0.64-0.78 mutations per billion base pairs per division.
  • Repeated copy-pasting of these cells results in more somatic genetic mutations, the older an individual is and the higher the turnover of the tissue.
  • These conditions are not inherited from parents but are a result of new genetic variations in somatic cells.

Cause of Concern 

  • Genetic Diseases:
    • Many genetic diseases arise from somatic genetic variants that occur during development, leading to various genetic diseases. 
    • Severity and distribution of the disease depends on how early or late during development the corresponding mutation occurred.
  • Cancer Development: 
    • Somatic genetic mutations can lead to the development of cancers and can also be accelerated by cancer. 
    • These mutations are often responsible for the formation of tumors through driver mutations.

Need of Understanding these Mutations 

  • Early Diagnosis: 
    • The relationship between somatic changes and cancer underscores the importance of understanding these mutations for early detection, diagnosis, and prognosis.
    • Understanding the timing and impact of these mutations during development is crucial for comprehending the severity and distribution of genetic disorders.
  • A Positive Change: Somatic changes can be beneficial in a genetic disease by changing a deleterious change to a normal one, a phenomenon known as revertant mosaicism. For example, around 10% of cases of Wiskott-Aldrich syndrome, a rare genetic immunodeficiency, have been found to have revertant mosaicism, as a result alleviating the severity of the disease in many individuals.
  • Immunity Building:
    • Somatic genetic variants play a vital role in the immune system’s ability to generate diverse antibodies.
    • Immune cells like B and T cells undergo significant somatic changes to produce a wide array of proteins that recognize and bind to pathogens. 
    • This diversity is critical for effective immune responses, and studying these variants can provide insights into immune-related disorders.

Global Example 

Somatic Mosaicism across Human Tissues’ (SMaHT) Network

  • The U.S. National Institutes of Health has launched a programme focused on understanding the breadth of somatic mosaicism and the biological and clinical significance of such somatic events in humans.
  • This network aims to catalyse study in the field by discovering somatic variants, developing tools and resources with which to study them, and improving ability to analyse, interpret, and organise them in different biological and clinical contexts.

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