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T ay-Sachs Disease

T ay-Sachs Disease. Colleen Connolly IB Biology II (Period 4/5) Mrs. Nall February 26, 2009. Two Types. There are two types of Tay-Sachs disease: Infantile (or Classical) Tay-Sachs and Late-onset Tay-Sachs (LOTS).

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T ay-Sachs Disease

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  1. Tay-Sachs Disease Colleen Connolly IB Biology II (Period 4/5) Mrs. Nall February 26, 2009

  2. Two Types • There are two types of Tay-Sachs disease: Infantile (or Classical) Tay-Sachs and Late-onset Tay-Sachs (LOTS). • Infantile Tay-Sachs is the most common type. It affects babies 3 to 6 months after birth. (That is when symptoms start to show.) • LOTS begins between adolescences and mid-30s. Not much is known about LOTS yet because it is a recently recognized condition.

  3. Cause • Tay-Sachs is caused by the lack of or an insufficient amount of hexosaminidase A (hex A) enzyme. • In Infantile (or classical) Tay-Sachs the body does not produce any hex A. • In Late-onset Tay-Sachs (LOTS) the body does not produce enough hex A. • Hex A breaks down fatty compounds called GM2 gangliosides. Without hex A the body accumulates toxic levels of these fatty compounds in the brain, impairing brain and nerve cells. • Tay-Sachs is an autosomal recessive disease. • For Infantile Tay-Sachs to occur the mutant gene must be inherited from both parents. • For Late-onset Tay-Sachs (LOTS) two Late-onset hex A genes are inherited or one Late-onset and one inactive gene are inherited.

  4. Symptoms • Infantile Tay-Sachs: • The baby appears healthy at birth. Symptoms show 3 to 6 months after birth. • An early sign is a red spot on the retina. • At 3 to 6 months the symptoms include decreased eye contact, twitchy eyes (myoclonic jerks), difficulty focusing on objects, excessive startling by sharp but not necessarily loud noises. • By 6 to 10 months the symptoms include loss of motor skills, difficulty sitting up or rolling over, limp and floppy muscles (hypotonia), decreased alertness and playfulness, decreased hearing (and eventually deafness), gradual loss of blindness, and an abnormal increase in head size (macrocephaly). • At 10 months and older the child may suffer from blindness, mental retardation, unresponsiveness to the environment, paralysis, seizures, difficulty swallowing, and difficulty breathing. • The brain and nervous system progressively deteriorate and the child will die at age 4 to 5. • Late-Onset Tay-Sachs (LOTS): • The first symptoms, which may include clumsiness or mood changes, may be subtle and go unnoticed when they develop between adolescence and mid-30s. • Later, the individual will suffer from personality changes, muscle weakness and/or twitching, slurred speech, impaired thinking and reasoning (which may cause memory problems, a short attention span, and/or difficulty comprehending), inability to distinguish between real and unreal (psychotic episodes), and possibly depression. • Life expectancy of an individual with LOTS is not yet known, as it is a newly identified form of Tay-Sachs,but depending on the severity of the symptoms LOTS may not shorten life expectancy at all.

  5. Healthy Neuron vs. Neuron Affect by Tay-Sachs The lysosome is the waste processing center of the cell, containing digestive enzymes.Notice that the lysosomes in the affected neuron are bulging.Bugling has occurred because Gangliosides have built up in these lysosomes of the affected neuron because it is not being broken down due to the lack of hex A in the lysosome.

  6. Treatment • There is no cure for Tay-Sachs. • There is no way to treat Tay-Sachs and the lack of hex A. Instead, patients focus on controlling the symptoms. • If the child suffers from seizures anticonvulsant medication may be taken to limit seizures. /Or, for example, if a LOTS patient becomes depressed that too can be treated with medication. • Respiratory problems may develop when children swallow food or liquid into their lungs, causing mucus to accumulate, thus making it harder to breath. Children are at high risk of respiratory infections. In fact, persistent infection is often the cause of death in Tay-Sachs patients. • Children may eventually need a feeding tube, either a Nasogastric (NG) tube or a Percutaneous Esophago-Gastrostomy (PEG) tube. • Chest physiotherapy (CPT) is done by respiratory therapists to reduce mucus accumulation in the lungs. Family can be trained to perform this therapy at home. • Proper nutrition and hydration help keep the airways open to assist with breathing. • Physical therapy may be used to stimulate the muscles and joints, to help maintain flexibility and range of motion. • Counseling is sometimes employed to help the patient control behavioral or mental disorders. • Mostly, family counseling and support groups are utilized to help cope with this devastating disease.

  7. Percent of People Inflicted • Tay-Sachs is very rare. • Each year about 12 to 16 cases of Tay-Sachs are diagnosed in the U.S., mostly the Infantile form. • In the general population, 1 in 250 people are carriers of this disease. • Tay-Sachs is most common in people of: • Ashkenazi Jewish descent (About 3%, or 1 in 27, Ashkenazi Jews are carriers.) • French-Canadian descent from the East Saint Lawrence River Valley • Cajun descent in Louisiana

  8. Screening • A physical exam may reveal or confirm symptoms of Tay-Sachs. • Either hex A testing (98% accurate) or DNA testing (94% accurate) is recommended for adults who are considering having children and are of Ashkenazi Jewish, French-Canadian or Cajun descent, or have a history of Tay-Sachs in the family. The test will determine if he/she is a carrier of the disease. • If both parents are carriers there is a 25% chance that their child will have Tay-Sachs and a 50% chance that their child will be a carrier. Genetic counseling is suggested for these couples. • A Tay-Sachs screen test can be done for women who are pregnant and at risk of having a child with Tay-Sachs. A blood sample can be taken from the placenta via chorionic villus sampling between the 10th and 12th weeks of pregnancy, or amniotic fluid surrounding the fetus can be extracted via amniocentesis between the 15th and 18th weeks of pregnancy. • A blood sample taken from a vein or the umbilical cord immediately after birth can detect the level of hex A being produced. • The Tay-Sachs screen test can also confirm LOTS in teens or adults who suffers from the symptoms. • A positive Tay-Sachs test should be confirmed with other genetic tests.

  9. Risk of having a child with Tay-Sachs if Both Parents are Carriers

  10. Society’s Interpretation • Being as this is an incredibly heart wrenching disease, society typically does not scorn or tease patients, especially Infantile Tay-Sachs patients, as these are children under 5 years of age. • Usually one cannot even physically detect symptoms until the patient is about 6 months old. • Once mental retardation and other aforementioned symptoms set in Tay-Sachs becomes more noticeable.

  11. How Tay-Sachs Disease Got its Name • Tay-Sachs disease was named after Warren Tay and Bernard Sachs. • Warren Tay (1843-1927) was a British ophthalmologist. In 1881 he described a patient with a cherry-red spot on the retina of the eye (one of the symptoms of Tay-Sachs). • Bernard Sachs (1858-1944) was a New York neurologist. He was the first to describe the cellular changes in a Tay-Sachs victim, several years after Tay. He also noted that most babies with Tay-Sachs disease were of eastern European Jewish origin.

  12. Bibliography • WebMD Medical Reference from Healthwise, Incorporated. April 4, 2008.http://children.webmd.com/tc/tay-sachs-disease-topic-overview. • Louis E. Bartoshesky, MD, MPH. Nemours Foundation. October 2008. http://kidshealth.org/parent/medical/genetic/tay_sachs.html. • National Institute of Neurological Disorders and Stroke. February 14, 2007.http://www.ninds.nih.gov/disorders/taysachs/taysachs.htm. • Mayo Foundation for Medical Education and Research. 2009. http://www.mayoclinic.org/tay-sachs-disease/. • March of Dimes Foundation. July 2006. http://search.marchofdimes.com/cgi-bin/MsmGo.exe?grab_id=6&page_id=1507840&query=TaySachs+Disease&hiword=DISEAS+DISEASES+Disease+TaySachs+. • Society for Neuroscience. 2009. http://images.google.com/imgres?imgurl=http://www.sfn.org/SiteObjects/published/0000BDF20016F63800FD712C3158BA55/0000BDF2000006250110C68C45857663/file/bb_feb2007_large.jpg&imgrefurl=http://www.sfn.org/index.cfm%3Fpagename%3DbrainBriefings_TreatingTaySachs&usg=__K_IdfmozeW7Rh27AqGem6JMnCtw=&h=325&w=400&sz=33&hl=en&start=1&um=1&tbnid=e7y-zJaANn5kjM:&tbnh=101&tbnw=124&prev=/images%3Fq%3Dtay-sachs%2Bdisease%26um%3D1%26hl%3Den%26sa%3DN.

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