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Werner syndrome (WS), also known as "adult progeria", is a rare, autosomal recessive disorder which is characterized by the appearance of premature aging.
DNA repair is a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolic activities and environmental factors such as radiation can cause DNA damage, resulting in as many as 1 million individual molecular lesions per cell per day. Many of these lesions cause structural damage to the DNA molecule and can alter or eliminate the cell's ability to transcribe the gene that the affected DNA encodes. Other lesions induce potentially harmful mutations in the cell's genome, which affect the survival of its daughter cells after it undergoes mitosis. As a consequence, the DNA repair process is constantly active as it responds to damage in the DNA structure. When normal repair processes fail, and when cellular apoptosis does not occur, irreparable DNA damage may occur, including double-strand breaks and DNA crosslinkages. This can eventually lead to malignant tumors, or cancer as per the two hit hypothesis.
Ataxia–telangiectasia, also referred to as ataxia–telangiectasia syndrome or Louis–Bar syndrome, is a rare, neurodegenerative, autosomal recessive disease causing severe disability. Ataxia refers to poor coordination and telangiectasia to small dilated blood vessels, both of which are hallmarks of the disease.
Bloom syndrome, is a rare autosomal recessive disorder characterized by short stature, predisposition to the development of cancer, and genomic instability. BS is caused by mutations in the BLM gene which is a member of the RecQ DNA helicase family. Mutations in other members of this family, namely WRN and RECQL4, are associated with the clinical entities Werner syndrome and Rothmund-Thomson syndrome, respectively. More broadly, Bloom syndrome is a member of a class of clinical entities that are characterized by chromosomal instability, genomic instability, or both and by cancer predisposition.
Non-homologous end joining (NHEJ) is a pathway that repairs double-strand breaks in DNA. NHEJ is referred to as "non-homologous" because the break ends are directly ligated without the need for a homologous template, in contrast to homology directed repair, which requires a homologous sequence to guide repair. The term "non-homologous end joining" was coined in 1996 by Moore and Haber.
ATM serine/threonine kinase, symbol ATM, is a serine/threonine protein kinase that is recruited and activated by DNA double-strand breaks. It phosphorylates several key proteins that initiate activation of the DNA damage checkpoint, leading to cell cycle arrest, DNA repair or apoptosis. Several of these targets, including p53, CHK2, BRCA1, NBS1 and H2AX are tumor suppressors.
Nijmegen breakage syndrome (NBS), is a rare autosomal recessive congenital disorder causing chromosomal instability, probably as a result of a defect in the double Holliday junction DNA repair mechanism and/or the synthesis dependent strand annealing mechanism for repairing double strand breaks in DNA.
Premature ovarian failure (POF) is the loss of function of the ovaries before age 40. A commonly cited triad for the diagnosis is amenorrhea, hypergonadotropism, and hypoestrogenism. If it has a genetic cause, it may be called gonadal dysgenesis.
Sister chromatid exchange (SCE) is the exchange of genetic material between two identical sister chromatids.
In biology and especially genetics, a mutant is an organism or a new genetic character arising or resulting from an instance of mutation, which is generally an alteration of the DNA sequence of the genome or chromosome of an organism. The term mutant is also applied to a virus with an alteration in its nucleotide sequence whose genome is RNA, rather than DNA. In multicellular eukaryotes, a DNA sequence may be altered in an individual somatic cell that then gives rise to a mutant somatic cell lineage as happens in cancer progression. Also in eukaryotes, alteration of a mitochondrial or plastid DNA sequence may give rise to a mutant lineage that is inherited separately from mutant genotypes in the nuclear genome. The natural occurrence of genetic mutations is integral to the process of evolution. The study of mutants is an integral part of biology; by understanding the effect that a mutation in a gene has, it is possible to establish the normal function of that gene.
Serine/threonine-protein kinase ATR also known as ataxia telangiectasia and Rad3-related protein (ATR) or FRAP-related protein 1 (FRP1) is an enzyme that, in humans, is encoded by the ATR gene. ATR belongs to the phosphatidylinositol 3-kinase-related kinase protein family. ATR is activated in response to single strand breaks.
Nibrin, also known as NBN or NBS1, is a protein which in humans is encoded by the NBN gene.
RAD52 homolog , also known as RAD52, is a protein which in humans is encoded by the RAD52 gene.
Structural maintenance of chromosomes protein 6 is a protein that in humans is encoded by the SMC6 gene.
DNA replication licensing factor MCM8 is a protein that in humans is encoded by the MCM8 gene.
LIG4 syndrome is an extremely rare condition caused by mutations in the DNA Ligase IV (LIG4) gene. Some mutations in this gene are associated with a resistance against multiple myeloma and Severe Combined Immunodeficiency. Severity of symptoms depends on the degree of reduced enzymatic activity of Ligase IV or gene expression. Ligase IV is a critical component of the non-homologous end joining (NHEJ) mechanism that repairs DNA double-strand breaks. It is employed in repairing DNA double-strand breaks caused by reactive oxygen species produced by normal metabolism, or by DNA damaging agents such as ionizing radiation. NHEJ is also used to repair the DNA double-strand break intermediates that occur in the production of T and B lymphocyte receptors.
Genome instability refers to a high frequency of mutations within the genome of a cellular lineage. These mutations can include changes in nucleic acid sequences, chromosomal rearrangements or aneuploidy. Genome instability does occur in bacteria. In multicellular organisms genome instability is central to carcinogenesis, and in humans it is also a factor in some neurodegenerative diseases such as amyotrophic lateral sclerosis or the neuromuscular disease myotonic dystrophy.
A cancer syndrome or family cancer syndrome is a genetic disorder in which inherited genetic mutations in one or more genes predispose the affected individuals to the development of cancers and may also cause the early onset of these cancers. Cancer syndromes often show not only a high lifetime risk of developing cancer, but also the development of multiple independent primary tumors. Many of these syndromes are caused by mutations in tumor suppressor genes, genes that are involved in protecting the cell from turning cancerous. Other genes that may be affected are DNA repair genes, oncogenes and genes involved in the production of blood vessels (angiogenesis). Common examples of inherited cancer syndromes are hereditary breast-ovarian cancer syndrome and hereditary non-polyposis colon cancer.
Chromosomal instability (CIN) is a type of genomic instability in which chromosomes are unstable, such that either whole chromosomes or parts of chromosomes are duplicated or deleted. More specifically, CIN refers to the increase in rate of addition or loss of entire chromosomes or sections of them. The unequal distribution of DNA to daughter cells upon mitosis results in a failure to maintain euploidy leading to aneuploidy. In other words, the daughter cells do not have the same number of chromosomes as the cell they originated from. Chromosomal instability is the most common form of genetic instability and cause of aneuploidy.
Penelope "Penny" Jeggo is a noted British molecular biologist, best known for her work in understanding damage to DNA. She is also known for her work with DNA gene mutations. Her interest in DNA damage has inspired her to research radiation biology and radiation therapy and how radiation affects DNA. Jeggo has almost 170 publication that pertain to DNA damage, radiation, and cancer research and has received 3 top science awards/medals for her research. Jeggo has also been a member of several organizations that pertain to radiation biology; these organizations include Committee on Medical Aspects of Radiation in the Environment (COMARE), National Institute for Radiation Science laboratory researcher, and the Multidisciplinary European Low Dose Initiative (MELODI). Not only is Jeggo a member of these prestigious organizations, but she is also an editor for several publication journals that are related to cancer and radiation biology. Jeggo is very passionate towards all her research and in an interview with Fiona Watt claimed that “Although my results contributed only the tiniest smidgeon to scientific knowledge, I gained immense satisfaction from it”.
References
- ↑ Taylor AM (2001). "Chromosome instability syndromes". Best Pract Res Clin Haematol. 14 (3): 631–44. doi:10.1053/beha.2001.0158. PMID 11640873.
- 1 2 Wood-Trageser MA, Gurbuz F, Yatsenko SA, Jeffries EP, Kotan LD, Surti U, Ketterer DM, Matic J, Chipkin J, Jiang H, Trakselis MA, Topaloglu AK, Rajkovic A (December 2014). "MCM9 mutations are associated with ovarian failure, short stature, and chromosomal instability". Am. J. Hum. Genet. 95 (6): 754–62. doi:10.1016/j.ajhg.2014.11.002. PMC 4259971 . PMID 25480036.
- ↑ Desai S, Wood-Trageser M, Matic J, Chipkin J, Jiang H, Bachelot A, Dulon J, Sala C, Barbieri C, Cocca M, Toniolo D, Touraine P, Witchel S, Rajkovic A (February 2017). "MCM8 and MCM9 Nucleotide Variants in Women With Primary Ovarian Insufficiency". J. Clin. Endocrinol. Metab. 102 (2): 576–582. doi:10.1210/jc.2016-2565. PMC 5413161 . PMID 27802094.