Down syndrome in the context of Genetic test

A syndrome is a set of medical signs and symptoms which are correlated with each other and often associated with a particular disease or disorder. The word derives from the Greek σύνδρομον, meaning "concurrence". When a syndrome is paired with a definite cause this becomes a disease. In some instances, a syndrome is so closely linked with a pathogenesis or cause that the words syndrome, disease, and disorder end up being used interchangeably for them. This substitution of terminology often confuses the reality and meaning of medical diagnoses. This is especially true of inherited syndromes. About one third of all phenotypes that are listed in OMIM are described as dysmorphic, which usually refers to the facial gestalt. For example, Down syndrome, Wolf–Hirschhorn syndrome, and Andersen–Tawil syndrome are disorders with known pathogeneses, so each is more than just a set of signs and symptoms, despite the syndrome nomenclature. In other instances, a syndrome is not specific to only one disease. For example, toxic shock syndrome can be caused by various toxins; another medical syndrome named as premotor syndrome can be caused by various brain lesions; and premenstrual syndrome is not a disease but simply a set of symptoms.

If an underlying genetic cause is suspected but not known, a condition may be referred to as a genetic association (often just "association" in context). By definition, an association indicates that the collection of signs and symptoms occurs in combination more frequently than would be likely by chance alone.

Special education (also known as special-needs education, aided education, alternative provision, exceptional student education, special ed., SDC, and SPED) is the practice of educating students in a way that accommodates their individual differences, disabilities, and special needs. This involves the individually planned and systematically monitored arrangement of teaching procedures, adapted equipment and materials, and accessible settings. These interventions are designed to help individuals with special needs achieve a higher level of personal self-sufficiency and success in school and in their community, which may not be available if the student were only given access to a typical classroom education.

Special education aims to provide accommodated education for students with disabilities such as learning disabilities, learning difficulties (such as dyslexia), communication disorders, emotional and behavioral disorders, physical disabilities (such as osteogenesis imperfecta, down syndrome, lissencephaly, Sanfilippo syndrome, and muscular dystrophy), developmental disabilities (such as autism spectrum disorder, and intellectual disabilities) and other disabilities. Students with disabilities are likely to benefit from additional educational services such as different approaches to teaching, the use of technology, a specifically adapted teaching area, a resource room, or a separate classroom.

Riget (English title: The Kingdom) is a Danish absurdist supernatural horror miniseries trilogy created by Lars von Trier and Tómas Gislason. Set in the neurosurgical ward of Copenhagen's Rigshospitalet (lit. 'The National Hospital', nicknamed "Riget", lit. 'the realm' or 'the kingdom'), each episode of the show follows the hospital's eccentric staff and patients as they encounter bizarre and sometimes supernatural phenomena. The series is notable for its wry humor, its muted sepia colour scheme, and the appearance of a chorus of dishwashers with Down syndrome, who discuss in intimate detail the strange occurrences in the hospital. The main theme's song was written by von Trier himself.

The first series of four episodes premiered from DR in November to December 1994, and was followed by a second series, Riget II, which aired in November 1997. A belated third and final series of five episodes, directed by von Trier and written by von Trier with Niels Vørsel, entitled Exodus, began filming in 2021 and was screened out of competition at the Venice Film Festival and at the Serial Killer festival in September 2022, and premiered on Nordic streaming platform Viaplay with the first two episodes on 9 October. The series premiered in select regions between 27 November and 25 December on streaming platform MUBI.

Intellectual disability (ID), also known as general learning disability (in the United Kingdom), and formerly mental retardation (in the United States), is a generalized neurodevelopmental disorder characterized by significant impairment in intellectual and adaptive functioning that is first apparent during childhood. Children with intellectual disabilities typically have an intelligence quotient (IQ) below 70 and deficits in at least two adaptive behaviors that affect everyday living. According to the DSM-5, intellectual functions include reasoning, problem solving, planning, abstract thinking, judgment, academic learning, and learning from experience. Deficits in these functions must be confirmed by clinical evaluation and individualized standard IQ testing. On the other hand, adaptive behaviors include the social, developmental, and practical skills people learn to perform tasks in their everyday lives. Deficits in adaptive functioning often compromise an individual's independence and ability to meet their social responsibility.

Intellectual disability is subdivided into syndromic intellectual disability, in which intellectual deficits associated with other medical and behavioral signs and symptoms are present, and non-syndromic intellectual disability, in which intellectual deficits appear without other abnormalities. Down syndrome and fragile X syndrome are examples of syndromic intellectual disabilities.

A chromosomal abnormality or chromosomal anomaly is a missing, extra, or irregular portion of chromosomal DNA. These can occur in the form of numerical abnormalities, where there is an atypical number of chromosomes, or as structural abnormalities, where one or more individual chromosomes are altered. Chromosome mutation was formerly used in a strict sense to mean a change in a chromosomal segment, involving more than one gene. Chromosome anomalies usually occur when there is an error in cell division following meiosis or mitosis. Chromosome abnormalities may be detected or confirmed by comparing an individual's karyotype, or full set of chromosomes, to a typical karyotype for the species via genetic testing.

Sometimes chromosomal abnormalities arise in the early stages of an embryo, sperm, or infant. They can be caused by various environmental factors. The implications of chromosomal abnormalities depend on the specific problem, they may have quite different ramifications. Diseases and conditions caused by chromosomal abnormalities are called chromosomal disorders or chromosomal aberrations. Some examples are Down syndrome and Turner syndrome. However, chromosomal abnormalities do not always lead to diseases. Among abnormalities, structural rearrangements of genes between chromosomes can be harmless if they are balanced, which means that a set of the chromosomes remains complete and there are no gene breaks across the chromosomes.

The development of the nervous system, or neural development (neurodevelopment), refers to the processes that generate, shape, and reshape the nervous system of animals, from the earliest stages of embryonic development to adulthood. The field of neural development draws on both neuroscience and developmental biology to describe and provide insight into the cellular and molecular mechanisms by which complex nervous systems develop, from nematodes and fruit flies to mammals.

Defects in neural development can lead to malformations such as holoprosencephaly, and a wide variety of neurological disorders including limb paresis and paralysis, balance and vision disorders, and seizures, and in humans other disorders such as Rett syndrome, Down syndrome and intellectual disability.

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 (genetic mother and father) 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 (e.g. to assess relatedness/ancestry or predict/diagnose genetic disorders), to gain information used for selective breeding, or for efforts to boost genetic diversity in endangered populations.

The variety of genetic tests has expanded throughout the years. Early forms of genetic testing which began in the 1950s involved counting the number of chromosomes per cell. Deviations from the expected number of chromosomes (46 in humans) could lead to a diagnosis of certain genetic conditions such as trisomy 21 (Down syndrome) or monosomy X (Turner syndrome). In the 1970s, a method to stain specific regions of chromosomes, called chromosome banding, was developed that allowed more detailed analysis of chromosome structure and diagnosis of genetic disorders that involved large structural rearrangements. In addition to analyzing whole chromosomes (cytogenetics), genetic testing has expanded to include the fields of molecular genetics and genomics which can identify changes at the level of individual genes, parts of genes, or even single nucleotide "letters" of DNA sequence. According to the National Institutes of Health, there are tests available for more than 2,000 genetic conditions, and one study estimated that as of 2018 there were more than 68,000 genetic tests on the market.

Aneuploidy is the presence of an abnormal number of chromosomes in a cell, for example a human somatic cell having 45 or 47 chromosomes instead of the usual 46. It does not include a difference of one or more complete sets of chromosomes. A cell with any number of complete chromosome sets is called a euploid cell.

An extra or missing chromosome is a common cause of some genetic disorders. Some cancer cells also have abnormal numbers of chromosomes. About 68% of human solid tumors are aneuploid. Aneuploidy originates during cell division when the chromosomes do not separate properly between the two cells (nondisjunction). Most cases of aneuploidy in the autosomes result in miscarriage, and the most common extra autosomal chromosomes among live births are 21, 18 and 13. Chromosome abnormalities are detected in 1 of 160 live human births. Autosomal aneuploidy is more dangerous than sex chromosome aneuploidy, as autosomal aneuploidy is almost always lethal to embryos that cease developing because of it.

Leukemia (also spelled leukaemia; pronounced /luːˈkiːmiːə/ loo-KEE-mee-ə) is a group of blood cancers that usually begin in the bone marrow and produce high numbers of abnormal blood cells. These blood cells are not fully developed and are called blasts or leukemia cells. Symptoms may include bleeding and bruising, bone pain, fatigue, fever, and an increased risk of infections. These symptoms occur due to a lack of normal blood cells. Diagnosis is typically made by blood tests or bone marrow biopsy.

The exact cause of leukemia is unknown. A combination of genetic factors and environmental (non-inherited) factors are believed to play a role. Risk factors include smoking, ionizing radiation, petrochemicals (such as benzene), prior chemotherapy, and Down syndrome. People with a family history of leukemia are also at higher risk. There are four main types of leukemia—acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL) and chronic myeloid leukemia (CML)—and a number of less common types. Leukemias and lymphomas both belong to a broader group of tumors that affect the blood, bone marrow, and lymphoid system, known as tumors of the hematopoietic and lymphoid tissues.

Clinical neuroscience is a branch of neuroscience that focuses on the scientific study of fundamental mechanisms that underlie diseases and disorders of the brain and central nervous system. It seeks to develop new ways of conceptualizing and diagnosing such disorders and ultimately of developing novel treatments.

A clinical neuroscientist is a scientist who has specialized knowledge in the field. Not all clinicians are clinical neuroscientists. Clinicians and scientists -including psychiatrists, neurologists, clinical psychologists, neuroscientists, and other specialists—use basic research findings from neuroscience in general and clinical neuroscience in particular to develop diagnostic methods and ways to prevent and treat neurobiological disorders. Such disorders include addiction, Alzheimer's disease, amyotrophic lateral sclerosis, anxiety disorders, attention deficit hyperactivity disorder, autism, bipolar disorder, brain tumors, depression, Down syndrome, dyslexia, epilepsy, Huntington's disease, multiple sclerosis, neurological AIDS, neurological trauma, pain, obsessive-compulsive disorder, Parkinson's disease, schizophrenia, sleep disorders, stroke and Tourette syndrome.

In clinical diagnostic and functional development, special needs (or additional needs) refers to individuals who require assistance for disabilities that may be medical, mental, or psychological. Guidelines for clinical diagnosis are given in both the Diagnostic and Statistical Manual of Mental Disorders and the International Classification of Diseases 9th edition. Special needs can range from people with autism, cerebral palsy, Down syndrome, dyslexia, dyscalculia, dyspraxia, dysgraphia, blindness, deafness, ADHD, and cystic fibrosis. They can also include cleft lips and missing limbs. The types of special needs vary in severity, and a student with a special need is classified as being a severe case when the student's IQ is between 20 and 35. These students typically need assistance in school, and have different services provided for them to succeed in a different setting.

In parts of the United Kingdom, special needs usually refers to special needs within an educational context. This is also referred to as special educational needs (SEN) or special educational needs and disabilities (SEND), additional support needs in Scotland, and in Wales is referred to as additional learning needs (ALN, Welsh: Anghenion Dysgu Ychwanegol, ADY) since 2021. In the United States, 19.4 percent of all children under the age of 18 (14,233,174 children) had special health care needs as of 2018.

Special education (special ed. or SPED), also known as special-needs education, aided education, alternative provision, exceptional student education, or special day class (SDC), is the practice of educating students in a way that accommodates their individual differences, disabilities, and special needs. This involves the individually planned and systematically monitored arrangement of teaching procedures, adapted equipment and materials, and accessible settings. These interventions are designed to help individuals with special needs achieve a higher level of personal self-sufficiency and success in school and in their community, which may not be available if the student were only given access to a typical classroom education.

Special education aims to provide accommodated education for students with disabilities such as learning disabilities, learning difficulties (such as dyslexia), communication disorders, emotional and behavioral disorders, physical disabilities (such as osteogenesis imperfecta, down syndrome, lissencephaly, Sanfilippo syndrome, and muscular dystrophy), developmental disabilities (such as autism spectrum disorder, and intellectual disabilities) and other disabilities. Students with disabilities are likely to benefit from additional educational services such as different approaches to teaching, the use of technology, a specifically adapted teaching area, a resource room, or a separate classroom.

A congenital heart defect (CHD), also known as a congenital heart anomaly, congenital cardiovascular malformation, and congenital heart disease, is a defect in the structure of the heart or great vessels that is present at birth. A congenital heart defect is classed as a cardiovascular disease. Signs and symptoms depend on the specific type of defect. Symptoms can vary from none to life-threatening. When present, symptoms are variable and may include rapid breathing, bluish skin (cyanosis), poor weight gain, and feeling tired. CHD does not cause chest pain. Most congenital heart defects are not associated with other diseases. A complication of CHD is heart failure. Due to recent advances in the management of patients with CHD, an increased number of patients may develop heart failure and might even require heart transplantation in future.

Congenital heart defects are the most common birth defect. In 2015, they were present in 48.9 million people globally. They affect between 4 and 75 per 1,000 live births, depending upon how they are diagnosed. In about 6 to 19 per 1,000 they cause a moderate to severe degree of problems. Congenital heart defects are the leading cause of birth defect-related deaths: in 2015, they resulted in 303,300 deaths, down from 366,000 deaths in 1990.The cause of a congenital heart defect is often unknown. Risk factors include certain infections during pregnancy such as rubella, use of certain medications or drugs such as alcohol or tobacco, parents being closely related, or poor nutritional status or obesity in the mother. Having a parent with a congenital heart defect is also a risk factor. A number of genetic conditions are associated with heart defects, including Down syndrome, Turner syndrome, and Marfan syndrome. Congenital heart defects are divided into two main groups: cyanotic heart defects and non-cyanotic heart defects, depending on whether the child has the potential to turn bluish in color. The defects may involve the interior walls of the heart, the heart valves, or the large blood vessels that lead to and from the heart.

Prenatal testing is a tool that can be used to detect some birth defects at various stages prior to birth. Prenatal testing consists of prenatal screening and prenatal diagnosis, which are aspects of prenatal care that focus on detecting problems with the pregnancy as early as possible. These may be anatomic and physiologic problems with the health of the zygote, embryo, or fetus, either before gestation even starts (as in preimplantation genetic diagnosis) or as early in gestation as practicable. Screening can detect problems such as neural tube defects, chromosome abnormalities, and gene mutations that would lead to genetic disorders and birth defects such as spina bifida, cleft palate, Down syndrome, trisomy 18, Tay–Sachs disease, sickle cell anemia, thalassemia, cystic fibrosis, muscular dystrophy, and fragile X syndrome. Some tests are designed to discover problems which primarily affect the health of the mother, such as PAPP-A to detect pre-eclampsia or glucose tolerance tests to diagnose gestational diabetes. Screening can also detect anatomical defects such as hydrocephalus, anencephaly, heart defects, and amniotic band syndrome.

Prenatal screening focuses on finding problems among a large population with affordable and noninvasive methods. Prenatal diagnosis focuses on pursuing additional detailed information once a particular problem has been found, and can sometimes be more invasive. The most common screening procedures are routine ultrasounds, blood tests, and blood pressure measurement. Common diagnosis procedures include amniocentesis and chorionic villus sampling. In some cases, the tests are administered to determine if the fetus will be aborted, though physicians and patients also find it useful to diagnose high-risk pregnancies early so that delivery can be scheduled in a tertiary care hospital where the baby can receive appropriate care.