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Tay-Sachs disease
Tay-Sachs disease T0067500 (tā′săks′)n. A hereditary disease that affects young children almost exclusively of eastern European Jewish descent, in which an enzyme deficiency leads to the accumulation of gangliosides in the brain and nerve tissue, resulting in intellectual disability, convulsions, blindness, and, ultimately, death.
[After Warren Tay (1843-1927), British physician, and Bernard, Sachs (1858-1944), American neurologist.]Tay-Sachs disease (ˌteɪˈsæks) n (Pathology) an inherited disorder, caused by a faulty recessive gene, in which lipids accumulate in the brain, leading to mental retardation and blindness. It occurs mostly in Ashkenazi Jews[C20: named after W. Tay (1843–1927), British physician, and B. Sachs (1858–1944), US neurologist]Tay′-Sachs′ disease` (ˈteɪˈsæks)
n. a degenerative brain disorder caused by lack of or deficiency in an essential enzyme, usu. resulting in mental and physical deterioration and death in early childhood. [1905–10; after Warren Tay (1843–1927), British ophthalmologist, and Bernard Sachs (1858–1944), U.S. neurologist, who described it independently] Tay-Sachs disease (tā′săks′) A hereditary disease in which the products of fat metabolism accumulate in the nervous system, causing retardation, paralysis, and death by the age of 3 or 4. It mostly affects children of eastern European Jewish descent.Thesaurus| Noun | 1. | Tay-Sachs disease - a hereditary disorder of lipid metabolism occurring most frequently in individuals of Jewish descent in eastern Europe; accumulation of lipids in nervous tissue results in death in early childhoodinfantile amaurotic idiocy, Sachs disease, Tay-Sachsmonogenic disease, monogenic disorder - an inherited disease controlled by a single pair of genesautosomal recessive defect, autosomal recessive disease - a disease caused by the presence of two recessive mutant genes on an autosomelipidosis - a disorder of lipid metabolism; abnormal levels of certain fats accumulate in the body |
Tay-Sachs disease
Tay-Sachs disease (tā`-săks`), rare hereditary disease caused by a genetic mutation that leaves the body unable to produce an enzymeenzyme,
biological catalyst. The term enzyme comes from zymosis, the Greek word for fermentation, a process accomplished by yeast cells and long known to the brewing industry, which occupied the attention of many 19th-century chemists.
..... Click the link for more information. necessary for fat metabolism in nerve cells, producing central nervous systemnervous system,
network of specialized tissue that controls actions and reactions of the body and its adjustment to the environment. Virtually all members of the animal kingdom have at least a rudimentary nervous system.
..... Click the link for more information. degeneration. The disease is named for a British ophthalmologist, Warren Tay, who first described the disease, in 1881, and a New York neurologist, Bernard Sachs, who first described the cellular changes and the genetic nature of the disease, in 1887. In infants, it is characterized by progressive mental deterioration, blindness, paralysis, epileptic seizures, and death, usually between ages three and five. Late-onset Tay-Sachs occurs in persons who have a genetic mutation that is similar but allows some production of the missing enzyme. There is no treatment for Tay-Sachs. Course of the Disease The enzyme involved in Tay-Sachs is called hexosaminidase A. Its absence allows a lipid called GM2 ganglioside to build up in the brain, destroying the nerve cells. The process starts in the fetus; the disease is clinically apparent in the first few months of life. Initial symptoms vary, but usually include a general slowing of development and loss of peripheral vision. By the age of one, most children are experiencing convulsions. The damage to the nervous system progresses inexorably, bringing with it an inability to swallow, difficulty in breathing, blindness, mental retardation, and paralysis. In late-onset Tay-Sachs, which is often misdiagnosed, the symptoms (ataxia, dysarthria, and muscle weakness) usually become apparent late in childhood or early in adulthood. About 40% of the patients display symptoms of bipolar disorderbipolar disorder,
formerly manic-depressive disorder
or manic-depression,
severe mental disorder involving manic episodes that are usually accompanied by episodes of depression.
..... Click the link for more information. . Life expectancy does not appear to be affected. Genetic Basis and Screening Tay-Sachs disease occurs primarily among Jews of Eastern European descent but is also found in French Canadians whose roots are in the St. Lawrence region, certain Cajuns in Louisiana, and some Amish communities. Tay-Sachs is an autosomal recessive disorder; a person must have two defective genes (one from each parent) in order for the disease to occur. Carriers, people with only one gene for the disorder, are physically unaffected. When both parents are carriers, each child has a 25% chance of getting the disease. If only one parent is a carrier, there is no chance that the child will get the disease, but there is a 50% chance that the child will be a carrier. The gene may be carried by many generations without a manifestation. For this reason, plus the historical lack of accurate diagnosis and routinely high infant mortality of past generations, there is often no known family history of the disease. Genetic screening (see genetic testinggenetic testing,
medical screening for genetic disorders, by examining either a person's DNA directly or a person's biochemistry or chromosomes for indirect evidence. Testing may be done to identify a genetic disorder a person has, whether the disorder is already evident or not,
..... Click the link for more information. ) for the disease has been possible since the early 1970s and is encouraged in high-risk populations. Blood tests of carriers reveal a reduced amount of the hexosaminidase A. If a couple elects to go forward with a pregnancy, fetal status (again utilizing hexosaminidase A levels) can be ascertained via chorionic villus samplingchorionic villus sampling
(CVS) or chorionic villus biopsy
(CVB) , diagnostic procedure in which a sample of chorionic villi from the developing placenta is removed from the uterus of a pregnant woman (see pregnancy) using a fine needle inserted through the abdomen or
..... Click the link for more information. or amniocentesisamniocentesis
, diagnostic procedure in which a sample of the amniotic fluid surrounding a fetus is removed from the uterus by means of a fine needle inserted through the abdomen of the pregnant woman (see pregnancy).
..... Click the link for more information. . Genetic screening and counseling has greatly reduced the incidence of the disease. Bibliography See M. M. Kaback, ed., Tay-Sachs Disease: Screening and Prevention (1977); W. Stockton, Altered Destinies (1979). Tay-Sachs disease[¦tā ¦saks di‚zēz] (medicine) A form of sphingolipidosis, transmitted as an autosomal recessive, in which there is an accumulation in neuronal cells of the neuraminic fraction of gangliosides; manifested clinically within the first few months of life by hypotonia progressing to spasticity, convulsions, and visual loss accompanied by the appearance of a cherry-red spot at the macula lutea. Also known as infantile amaurotic familial idiocy. Tay-Sachs disease
Tay-Sachs Disease DefinitionTay-Sachs disease is a genetic disorder caused by a missing enzyme that results in the accumulation of a fatty substance in the nervous system. This results in disability and death.DescriptionGangliosides are fatty substances necessary for the proper development of the brain and nerve cells (nervous system). Under normal conditions, gangliosides are continuously broken down, so that an appropriate balance is maintained. In Tay-Sachs disease, the enzyme necessary for removing excess gangliosides is missing. This allows gangliosides to accumulate throughout the brain, and is responsible for the disability associated with the disease.Tay-Sachs disease is particularly common among Jewish people of Eastern European and Russian (Ashkenazi) origin. About one out of every 3,600 babies born to Ashkenazi Jewish couples will have the disease. Tay-Sachs is also more common among certain French-Canadian and Cajun French families.Causes and symptomsTay-Sachs is caused by a defective gene. Genes are located on chromosomes, and serve to direct specific development/processes within the body. The genetic defect in Tay-Sachs disease results in the lack of an enzyme called hexosaminidase A. Without this enzyme, gangliosides cannot be degraded. They build up within the brain, interfering with nerve functioning. Because Tay-Sachs is a recessive disorder, only people who receive two defective genes (one from the mother and one from the father) will actually have the disease. People who have only one defective gene and one normal gene are called carriers. They carry the defective gene and thus the possibility of passing the gene and/or the disease onto their offspring.When a carrier and a non-carrier have children, none of their children will actually have Tay-Sachs. It is likely that 50% of their children will be carriers themselves. When two carriers have children, their children have a 25% chance of having normal genes, a 50% chance of being carriers of the defective gene, and a 25% chance of having two defective genes. The two defective genes cause the disease itself.Classic Tay-Sachs disease strikes infants around the age of six months. Up until this age, the baby will appear to be developing normally. When Tay-Sachs begins to show itself, the baby will stop interacting with other people and develop a staring gaze. Normal levels of noise will startle the baby to an abnormal degree. By about one year of age, the baby will have very weak, floppy muscles, and may be completely blind. The head will be quite large. Patients also present with loss of peripheral (side) vision, inability to breath and swallow, and paralysis as the disorder progresses. Seizures become a problem between ages one and two, and the baby usually dies by about age four.A few variations from this classical progression of Tay-Sachs disease are possible:- Juvenile hexosaminidase A deficiency. Symptoms appear between ages two and five; the disease progresses more slowly, with death by about 15 years.
- Chronic hexosaminidase A deficiency. Symptoms may begin around age five, or may not occur until age 20-30. The disease is milder. Speech becomes slurred. The individual may have difficulty walking due to weakness, muscle cramps, and decreased coordination of movements. Some individuals develop mental illness. Many have changes in intellect, hearing, or vision.
DiagnosisExamination of the eyes of a child with Tay-Sachs disease will reveal a characteristic cherry-red spot at the back of the eye (in an area called the retina). Tests to determine the presence and quantity of hexosaminidase A can be performed on the blood, specially treated skin cells, or white blood cells. A carrier will have about half of the normal level of hexosaminidase A present, while a patient with the disease will have none.TreatmentThere is no treatment for Tay-Sachs disease.PrognosisSadly, the prognosis for a child with classic Tay-Sachs disease is certain death. Because the chronic form of Tay-Sachs has been discovered recently, prognosis for this type of the disease is not completely known.PreventionPrevention involves identifying carriers of the disease and providing them with appropriate information concerning the chance of their offspring having Tay-Sachs disease. When the levels of hexosaminidase A are half the normal level, a person is a carrier of the defective gene. Blood tests of carriers reveals reduction of hexosaminidase A.Key termsGanglioside — A fatty (lipid) substance found within the brain and nerve cells.When a woman is already pregnant, tests can be performed on either the cells of the baby (aminocentesis) or the placenta (chorionic villus sampling) to determine whether the baby will have Tay-Sachs disease.ResourcesOrganizationsLate Onset Tay-Sachs Foundation. 1303 Paper Mill Road, Erdenheim, PA 19038. (800)672-2022.March of Dimes Birth Defects Foundation. 1275 Mamaroneck Avenue, White Plains, NY 10605. (888) 663-4637. resourcecenter@modimes.org. http://www.modimes.org.Tay-Sachs disease [ta saks] the infantile form of lipofuscinosis" >neuronal ceroid-lipofuscinosis, inherited as an autosomal recessive trait and affecting chiefly Ashkenazic Jews. With each pregnancy couples who are carriers have a one in four chance of having a child with the condition, a one in two chance of having a carrier like themselves, and a one in four chance of having a child who neither has the disease nor is a carrier. It is a progressive disorder marked by degeneration of brain tissue and the maculas (with formation of a cherry red spot on both retinas) and by dementia, blindness, and death. Tay-Sachs disease is a sphingolipidosis in which the error of metabolism" >inborn error of metabolism is a deficiency of the enzyme hexosaminidase A, resulting in accumulation of GM2 ganglioside in the brain.
It is possible to test for this disease in the unborn fetus at 14 weeks of pregnancy. An absence of hexosaminidase A indicates conclusively that the fetus has Tay-Sachs disease. Carriers of the trait have lowered levels of the enzyme in their blood, thus permitting screening of populations most susceptible to transmission of the trait to their offspring and genetic counseling of known carriers. No therapy is currently available. Most children with Tay-Sachs disease die of bronchopneumonia at 3 to 4 years of age.
The National Tay-Sachs and Allied Diseases Association (NTSAD) is dedicated to the treatment and prevention of Tay-Sachs, canavan, and related diseases. It provides information and support services to individuals and families affected by the diseases, as well as to the public at large. Their address is National Tay-Sachs and Allied Diseases Association, 2001 Beacon Street, Suite 204, Boston MA 02135. The telephone number is 800-906-8723.Tay-Sachs dis·ease (tā saks), a lysosomal storage disease, resulting from hexosaminidase A deficiency. The monosialoganglioside is stored in central and peripheral neuronal cells. Infants present with hyperacusis and irritability, hypotonia, and failure to develop motor skills. Blindness with macular cherry red spots and seizures are evident in the first year. Death occurs within a few years. Autosomal-recessive transmission; found primarily in Jewish people. Synonym(s): infantile GM2 gangliosidosisTay-Sachs disease (tā′săks′)n. A hereditary disease that affects young children almost exclusively of eastern European Jewish descent, in which an enzyme deficiency leads to the accumulation of gangliosides in the brain and nerve tissue, resulting in intellectual disability, convulsions, blindness, and, ultimately, death.Tay-Sachs disease GM2-gangliosidosis Pediatric neurology A rare AR lipid storage disease, most common in Ashkenazi Jews–carrier frequency 1:30, due to hexosaminidase A deficiency, resulting in accumulation of gangliosides in neurons, cerebellum, axons Clinical Onset at 4-6 months with arrest and decline of psychomotor activities, irritability, hyperacusis, convulsions, chorioathetosis, spasticity, decerebrate rigidity, death by age 3. See Gangliosidosis. Tay-Sachs dis·ease (tā saks di-zēz') A lysosomal storage disease resulting from hexosaminidase-A deficiency. The monosialoganglioside is stored in central and peripheral neuronal cells. Infants present with hyperacusis and irritability, hypotonia, and failure to develop motor skills. Blindness with macular cherry-red spots and seizures are evident in the first year. Tay-Sachs disease A recessive genetic disorder, affecting mainly Ashkenazi Jews, in which the absence of an enzyme necessary for the breakdown of ganglioside in the nervous system leads to damaging accumulation of this material. The condition appears soon after birth and features blindness, deafness, progressive dementia, seizures, paralysis and death, usually before the age of 3. There is no effective treatment but the diagnosis can be made before birth by CHORIONIC VILLUS SAMPLING and termination of pregnancy considered. (Warren Tay, 1843–1927, British ophthalmologist; and Bernard Sachs, 1858–1944, American neurologist).Tay-Sachs disease a lethal human condition in which children who are apparently normal at birth show signs within six months of marked deterioration of brain and spinal cord. By the age of one year the child can only lie helplessly, becoming mentally retarded, increasingly blind and paralysed. Death occurs between three and four years, with no known survivors and no cure. The condition is controlled by the recessive alleles of a gene located on chromosome 15, double recessives producing a deficient amount of the enzyme hexosaminidase A which leads to the accumulation of complex fatty substances in the CENTRAL NERVOUS SYSTEM.Sachs, Bernard, U.S. neurologist, 1858-1944. Tay-Sachs disease - see under Tay
Tay, Warren, English physician, 1843-1927. Tay cherry-red spot - the ophthalmoscopic appearance of the normal choroid beneath the fovea centralis. Synonym(s): cherry-red spotTay-Sachs disease - cerebral sphingolipidosis, infantile type. Synonym(s): infantile GM2 gangliosidosisTay-Sachs dis·ease (tā saks di-zēz') A lysosomal storage disease resulting from hexosaminidase-A deficiency. Tay-Sachs disease
Related to Tay-Sachs disease: phenylketonuria, Niemann-Pick disease, cystic fibrosis, sickle cell anemiaSynonyms for Tay-Sachs diseasenoun a hereditary disorder of lipid metabolism occurring most frequently in individuals of Jewish descent in eastern EuropeSynonyms- infantile amaurotic idiocy
- Sachs disease
- Tay-Sachs
Related Words- monogenic disease
- monogenic disorder
- autosomal recessive defect
- autosomal recessive disease
- lipidosis
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