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.
Huntington's disease (HD), also known as Huntington's chorea, is an incurable neurodegenerative disease that is mostly inherited. The earliest symptoms are often subtle problems with mood or mental/psychiatric abilities. A general lack of coordination and an unsteady gait often follow. It is also a basal ganglia disease causing a hyperkinetic movement disorder known as chorea. As the disease advances, uncoordinated, involuntary body movements of chorea become more apparent. Physical abilities gradually worsen until coordinated movement becomes difficult and the person is unable to talk. Mental abilities generally decline into dementia, depression, apathy, and impulsivity at times. The specific symptoms vary somewhat between people. Symptoms usually begin between 30 and 50 years of age, and can start at any age but are usually seen around the age of 40. The disease may develop earlier in each successive generation. About eight percent of cases start before the age of 20 years, and are known as juvenile HD, which typically present with the slow movement symptoms of Parkinson's disease rather than those of chorea.
Genetic testing, also known as DNA testing, is used to identify changes in DNA sequence or chromosome structure. Genetic testing can also include measuring the results of genetic changes, such as RNA analysis as an output of gene expression, or through biochemical analysis to measure specific protein output. In a medical setting, genetic testing can be used to diagnose or rule out suspected genetic disorders, predict risks for specific conditions, or gain information that can be used to customize medical treatments based on an individual's genetic makeup. Genetic testing can also be used to determine biological relatives, such as a child's biological parentage through DNA paternity testing, or be used to broadly predict an individual's ancestry. Genetic testing of plants and animals can be used for similar reasons as in humans, to gain information used for selective breeding, or for efforts to boost genetic diversity in endangered populations.
Genome: The Autobiography of a Species in 23 Chapters is a 1999 popular science book by the science writer Matt Ridley, published by Fourth Estate. The chapters are numbered for the pairs of human chromosomes, one pair being the X and Y sex chromosomes, so the numbering goes up to 22 with Chapter X and Y couched between Chapters 7 and 8.
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.
Spinocerebellar ataxia (SCA) is a progressive, degenerative, genetic disease with multiple types, each of which could be considered a neurological condition in its own right. An estimated 150,000 people in the United States have a diagnosis of spinocerebellar ataxia at any given time. SCA is hereditary, progressive, degenerative, and often fatal. There is no known effective treatment or cure. SCA can affect anyone of any age. The disease is caused by either a recessive or dominant gene. In many cases people are not aware that they carry a relevant gene until they have children who begin to show signs of having the disorder.
Medical genetics is the branch of medicine that involves the diagnosis and management of hereditary disorders. Medical genetics differs from human genetics in that human genetics is a field of scientific research that may or may not apply to medicine, while medical genetics refers to the application of genetics to medical care. For example, research on the causes and inheritance of genetic disorders would be considered within both human genetics and medical genetics, while the diagnosis, management, and counselling people with genetic disorders would be considered part of medical genetics.
Huntingtin(Htt) is the protein coded for in humans by the HTT gene, also known as the IT15 ("interesting transcript 15") gene. Mutated HTT is the cause of Huntington's disease (HD), and has been investigated for this role and also for its involvement in long-term memory storage.
Public health genomics is the use of genomics information to benefit public health. This is visualized as more effective preventive care and disease treatments with better specificity, tailored to the genetic makeup of each patient. According to the Centers for Disease Control and Prevention (U.S.), Public Health genomics is an emerging field of study that assesses the impact of genes and their interaction with behavior, diet and the environment on the population's health.
SET domain containing 2 is an enzyme that in humans is encoded by the SETD2 gene.
Huntington's disease has been shown in numerous formats, more so as awareness of the condition has increased. Here is a list of references to it in popular culture;
Nancy Wexler FRCP is an American geneticist and the Higgins Professor of Neuropsychology in the Departments of Neurology and Psychiatry of the Columbia University College of Physicians and Surgeons, best known for her involvement in the discovery of the location of the gene that causes Huntington's disease. She earned a Ph.D. in clinical psychology but instead chose to work in the field of genetics.
Anne Buckingham Young is an American physician and neuroscientist who has made major contributions to the study of neurodegenerative diseases, with a focus on movement disorders like Huntington's disease and Parkinson's disease. Young completed her undergraduate studies at Vassar College and earned a dual MD/PhD from Johns Hopkins Medical School. She has held faculty positions at University of Michigan and Harvard University. She became the first female chief of service at Massachusetts General Hospital when she was appointed Chief of Neurology in 1991. She retired from this role and from clinical service in 2012. She is a member of many academic societies and has won numerous awards. Young is also the only person to have been president of both the international Society for Neuroscience and the American Neurological Association.
Richard M. Myers is an American geneticist and biochemist known for his work on the Human Genome Project (HGP). The National Human Genome Research Institute says the HGP “[gave] the world a resource of detailed information about the structure, organization and function of the complete set of human genes.” Myers' genome center, in collaboration with the Joint Genome Institute, contributed more than 10 percent of the data in the project.
Jeffrey Bryan Carroll is an American scientific researcher in the field of Huntington's disease (HD). As a carrier of the abnormal gene that causes HD, he is also a public advocate for families affected by the disease, and co-founder of the HD research news platform HDBuzz. His life and work were the subject of a 2011 Gemini award-nominated CBC documentary feature. Carroll is an Associate Professor of neuroscience in the Department of Psychology at Western Washington University.
Milton Wexler was a Los Angeles psychoanalyst who was responsible for the creation of the Hereditary Disease Foundation.
A human disease modifier gene is a modifier gene that alters expression of a human gene at another locus that in turn causes a genetic disease. Whereas medical genetics has tended to distinguish between monogenic traits, governed by simple, Mendelian inheritance, and quantitative traits, with cumulative, multifactorial causes, increasing evidence suggests that human diseases exist on a continuous spectrum between the two.
Michelle Gray is an American neuroscientist and assistant professor of neurology and neurobiology at the University of Alabama Birmingham. Gray is a researcher in the study of the biological basis of Huntington's disease (HD). In her postdoctoral work, she developed a transgenic mouse line, BACHD, that is now used worldwide in the study of HD. Gray's research now focuses on the role of glial cells in HD. In 2020 Gray was named one of the 100 Inspiring Black Scientists in America by Cell Press. She is also a member of the Hereditary Disease Foundation’s scientific board.
Edward Wild, also known as Ed Wild, is a British neurologist and neuroscientist in the field of Huntington's disease and an advocate for scientific outreach to the public. He co-founded the Huntington's research news platform HDBuzz in 2010. He is a professor of neurology at UCL Institute of Neurology and is an associate director of the UCL Huntington's Disease Centre. He is also a consultant neurologist at the National Hospital for Neurology and Neurosurgery in London.
Georg Bernhard Landwehrmeyer FRCP is a German neurologist and neuroscientist in the field of neurodegeneration primarily focusing on Huntington's disease. Landwehrmeyer is a professor of neurology at Ulm University Hospital. He was one of the founders of the European Huntington's Disease Network (EHDN) in 2004 and was chairman of its executive committee until 2014.
