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A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosomal abnormality. Although polygenic disorders are the most common, the term is mostly used when discussing disorders with a single genetic cause, either in a gene or chromosome. The mutation responsible can occur spontaneously before embryonic development, or it can be inherited from two parents who are carriers of a faulty gene or from a parent with the disorder. When the genetic disorder is inherited from one or both parents, it is also classified as a hereditary disease. Some disorders are caused by a mutation on the X chromosome and have X-linked inheritance. Very few disorders are inherited on the Y chromosome or mitochondrial DNA.
The human genome is a complete set of nucleic acid sequences for humans, encoded as DNA within the 23 chromosome pairs in cell nuclei and in a small DNA molecule found within individual mitochondria. These are usually treated separately as the nuclear genome and the mitochondrial genome. Human genomes include both protein-coding DNA sequences and various types of DNA that does not encode proteins. The latter is a diverse category that includes DNA coding for non-translated RNA, such as that for ribosomal RNA, transfer RNA, ribozymes, small nuclear RNAs, and several types of regulatory RNAs. It also includes promoters and their associated gene-regulatory elements, DNA playing structural and replicatory roles, such as scaffolding regions, telomeres, centromeres, and origins of replication, plus large numbers of transposable elements, inserted viral DNA, non-functional pseudogenes and simple, highly-repetitive sequences. Introns make up a large percentage of non-coding DNA. Some of this non-coding DNA is non-functional junk DNA, such as pseudogenes, but there is no firm consensus on the total amount of junk DNA.
Genomics is an interdisciplinary field of biology focusing on the structure, function, evolution, mapping, and editing of genomes. A genome is an organism's complete set of DNA, including all of its genes as well as its hierarchical, three-dimensional structural configuration. In contrast to genetics, which refers to the study of individual genes and their roles in inheritance, genomics aims at the collective characterization and quantification of all of an organism's genes, their interrelations and influence on the organism. Genes may direct the production of proteins with the assistance of enzymes and messenger molecules. In turn, proteins make up body structures such as organs and tissues as well as control chemical reactions and carry signals between cells. Genomics also involves the sequencing and analysis of genomes through uses of high throughput DNA sequencing and bioinformatics to assemble and analyze the function and structure of entire genomes. Advances in genomics have triggered a revolution in discovery-based research and systems biology to facilitate understanding of even the most complex biological systems such as the brain.
The Y chromosome is one of two sex chromosomes in therian mammals and other organisms. The other sex chromosome is the X chromosome. Y is normally the sex-determining chromosome in many species, since it is the presence or absence of Y that determines the male or female sex of offspring produced in sexual reproduction. In mammals, the Y chromosome contains the gene SRY, which triggers male development. The DNA in the human Y chromosome is composed of about 62 million base pairs, making it similar in size to chromosome 19. The Y chromosome is passed only from XY parent to XY offspring. With a 30% difference between humans and chimpanzees, the Y chromosome is one of the fastest-evolving parts of the human genome. The human Y chromosome carries 693 genes, with 107 of these being protein-coding, but some genes are repeated and that makes the number of exclusive protein-coding genes just 42, the numbers are given for telomere-to-telomere CHM13. CCDS only classified 63 out of 107. All single-copy Y-linked genes are hemizygous except in cases of aneuploidy such as XYY syndrome or XXYY syndrome. Because of fake gaps inserted in GRCh38 it may be not obvious that CHM13 added 30 million base pairs into the Y chromosome, which is almost half of it that was unknown before 2022.
The Marine Biological Laboratory (MBL) is an international center for research and education in biological and environmental science. Founded in Woods Hole, Massachusetts, in 1888, the MBL is a private, nonprofit institution that was independent for most of its history, but became officially affiliated with the University of Chicago on July 1, 2013. It also collaborates with numerous other institutions.
Repeated sequences are short or long patterns of nucleic acids that occur in multiple copies throughout the genome. In many organisms, a significant fraction of the genomic DNA is repetitive, with over two-thirds of the sequence consisting of repetitive elements in humans. Some of these repeated sequences are necessary for maintaining important genome structures such as telomeres or centromeres.
X-inactivation is a process by which one of the copies of the X chromosome is inactivated in therian female mammals. The inactive X chromosome is silenced by being packaged into a transcriptionally inactive structure called heterochromatin. As nearly all female mammals have two X chromosomes, X-inactivation prevents them from having twice as many X chromosome gene products as males, who only possess a single copy of the X chromosome.
Mary Frances Lyon was an English geneticist best known for her discovery of X-chromosome inactivation, an important biological phenomenon.
Human genetics is the study of inheritance as it occurs in human beings. Human genetics encompasses a variety of overlapping fields including: classical genetics, cytogenetics, molecular genetics, biochemical genetics, genomics, population genetics, developmental genetics, clinical genetics, and genetic counseling.
The Human Genome Project (HGP) was an international scientific research project with the goal of determining the base pairs that make up human DNA, and of identifying, mapping and sequencing all of the genes of the human genome from both a physical and a functional standpoint. It started in 1990 and was completed in 2003. It remains the world's largest collaborative biological project. Planning for the project started after it was adopted in 1984 by the US government, and it officially launched in 1990. It was declared complete on April 14, 2003, and included about 92% of the genome. Level "complete genome" was achieved in May 2021, with a remaining only 0.3% bases covered by potential issues. The final gapless assembly was finished in January 2022.
A dicentric chromosome is an abnormal chromosome with two centromeres. It is formed through the fusion of two chromosome segments, each with a centromere, resulting in the loss of acentric fragments and the formation of dicentric fragments. The formation of dicentric chromosomes has been attributed to genetic processes, such as Robertsonian translocation and paracentric inversion. Dicentric chromosomes have important roles in the mitotic stability of chromosomes and the formation of pseudodicentric chromosomes. Their existence has been linked to certain natural phenomena such as irradiation and have been documented to underlie certain clinical syndromes, notably Kabuki syndrome. The formation of dicentric chromosomes and their implications on centromere function are studied in certain clinical cytogenetics laboratories.
Jack William Szostak is a Canadian American biologist of Polish British descent, Nobel Prize laureate, university professor at the University of Chicago, former Professor of Genetics at Harvard Medical School, and Alexander Rich Distinguished Investigator at Massachusetts General Hospital, Boston. Szostak has made significant contributions to the field of genetics. His achievement helped scientists to map the location of genes in mammals and to develop techniques for manipulating genes. His research findings in this area are also instrumental to the Human Genome Project. He was awarded the 2009 Nobel Prize for Physiology or Medicine, along with Elizabeth Blackburn and Carol W. Greider, for the discovery of how chromosomes are protected by telomeres.
Xist is a non-coding RNA on the X chromosome of the placental mammals that acts as a major effector of the X-inactivation process. It is a component of the Xic – X-chromosome inactivation centre – along with two other RNA genes and two protein genes.
Edith Heard is a British-French researcher in epigenetics and since January 2019 has been the Director General of the European Molecular Biology Laboratory (EMBL). She is also Professor at the Collège de France, holding the Chair of Epigenetics and Cellular Memory. From 2010 to 2018, Heard was the Director of the Genetics and Developmental Biology department at the Curie Institute (Paris), France. Heard is noted for her studies of X-chromosome-inactivation.
Andrea Ballabio, M.D., is an Italian scientist and academic professor. He is director of the Telethon Institute of Genetics and Medicine (TIGEM) of Pozzuoli; professor of medical genetics at the Federico II University of Naples and visiting professor of genetics at Baylor College of Medicine in Houston, Texas, US and at the University of Oxford-UK.
Jeannie T. Lee is a Professor of Genetics at Harvard Medical School and the Massachusetts General Hospital, and a Howard Hughes Medical Institute Investigator. She is known for her work on X-chromosome inactivation and for discovering the functions of a new class of epigenetic regulators known as long noncoding RNAs (lncRNAs), including Xist and Tsix.
Carolyn J. Brown is a Canadian geneticist and Professor in the Department of Medical Genetics at the University of British Columbia. Brown is known for her studies on X-chromosome inactivation, having discovered the human XIST gene in 1990.
Barbara Ruben Migeon is a professor at the Johns Hopkins University Institute of Genetic Medicine. She founded the Johns Hopkins University program in Human Genetics and Molecular Biology. Migeon is the author of Females are Mosaics: X inactivation and sex differences in disease. She was awarded the American College of Medical Genetics and Genomics Dimes/Colonel Harland D. Sanders Lifetime Achievement Award in 2016.
Jórunn Erla Eyfjörð is an Icelandic molecular biologist and professor emerita at the Faculty of Medicine of the University of Iceland. She is known for her research on breast cancer genetics.
Grant Robert Sutherland is a retired Australian human geneticist and celebrated cytogeneticist. He was the Director, Department of Cytogenetics and Molecular Genetics, Adelaide Women's and Children's Hospital for 27 years (1975-2002), then became the Foundation Research Fellow there until 2007. He is an Emeritus Professor in the Departments of Paediatrics and Genetics at the University of Adelaide.
References
- ↑ Enterprise Newspapers Staff (15 December 2014). "New President And Director At MBL". CapeNews.net. Retrieved 5 March 2016.
- ↑ "Huntington F. Willard". Archived from the original on 2015-04-03. Retrieved 2015-04-02.
- ↑ "Huntington F. Willard to Step Down as Marine Biological Laboratory President". www.mbl.edu. Archived from the original on 10 September 2018. Retrieved 16 June 2017.
- ↑ "MBL Director Huntington Willard elected to National Academy of Medicine". uchicago.edu. 17 October 2016. Retrieved 16 June 2017.
- ↑ "GCB Faculty". duke.edu. Retrieved 5 March 2016.
- ↑ "Huntington F. Willard, PhD at DukeHealth.org". dukehealth.org. Archived from the original on 7 December 2006. Retrieved 16 June 2017.
- ↑ Brown, Carolyn J.; Ballabio, Andrea; Rupert, James L.; Lafreniere, Ronald G.; Grompe, Markus; Tonlorenzi, Rossana; Willard, Huntington F. (1991). "A gene from the region of the human X inactivation centre is expressed exclusively from the inactive X chromosome". Nature. 349 (6304): 38–44. Bibcode:1991Natur.349...38B. doi:10.1038/349038a0. PMID 1985261. S2CID 4332325.
