21. IDPH - Center For Congenital And Inherited Disorders Birth Defects and genetic disorders. The following list of disorders is a small list and by no down syndrome is the most common chromosome disorder. http://www.idph.state.ia.us/genetics/genetic_disorders.asp

document.getElementById("CornerImage").src="../common/images/corner/" + (getNumber('26')+1) + ".jpg" Search IDPH IDPH Lucas State Ofc. Bldg 321 E. 12th Street Des Moines, IA 50319 IDPH Quick Links 125th Anniversary Accessibility Availability of Funds Birth, Death, and Marriage Certificates ... State of Iowa Advancing Health Through the Generations Iowa Department of Public Health Comments or questions about this site should be directed to the webmaster Site best viewed with Internet Explorer 5.5+ at 800x600 resolution or higher. Home Advisory Committee Birth Defects/Genetic Disorders Contact Us ... Resources Birth Defects and Genetic Disorders The following list of disorders is a small list and by no means encompasses all genetic disorders. The disorders listed are ones that are mentioned throughout our web site Abdominal wall defects are birth defects of the abdominal wall. There are two types of abdominal wall defects, omphalocele and gastroschisis. Omphalocele results from the incomplete closure of the umbilicus. The birth defect involves the protrusion of abdominal organs such as the intestine and liver into the umbilical cord. A membrane always covers an omphalocele, although sometimes this membrane may rupture. A ruptured omphalocele may be mistaken for a gastroschisis. Infants with omphalocele may have other birth defects, including chromosomal abnormalities.   Gastroschisis does not involve the umbilicus. The birth defect results from the protrusion of intestine and sometimes liver outside of the abdomen. This defect usually occurs to the right of the umbilicus and never includes a covering membrane. Infants with gastroschisis tend not to have other birth defects. Gastroschisis is not associated with chromosomal abnormalities.

22. Special Child: Disorder Zone Archives - Down Syndrome down syndrome (DS) is a genetic disorder that is caused by an extra chromosome 21 that is present in all or some of the individual’s cells. http://www.specialchild.com/archives/dz-007.html

Disorder Zone Archives Down Syndrome Jacob Spiegel Melina Lerma Introduction The additional chromosome is almost always the result of faulty cell division, in either the egg or sperm, resulting in 3 chromosome 21s (2 from the egg and 1 from the sperm, or vice-versa). Though the extra chromosome could come from either the father or the mother, only 5% of the cases have been traced to the father. Women age 35 years and older have a significantly increased chance of having a child with DS, however, 80% of children born with DS are actually born to mothers under the age of 35 years due to higher fertility rates. DS is one of the most common chromosome abnormalities. It is estimated that the incidence is between 1 in 800 to 1,000 live births. There are approximately 350,000 individuals in the United States with DS. It occurs in all racial, ethnic, and socioeconomic groups. Recent research shows that slightly more males than females are born with DS in comparison with the general population. Down syndrome was first accurately described in 1866 by an English physician named John Langdon Down. Then, in 1959, a French physician named Jerome Lejeune identified Down syndrome as a chromosome anomaly. It was Lejeune who observed 47 chromosomes in individuals with DS, rather than 46 chromosomes.

23. Genetic Disorders & Birth Defects: Down's Syndrome down s syndrome is a genetic disorder. In almost all cases, it is not passed down through families. Instead, it is the result of a single faulty egg or http://www.baptistonline.org/health/library/gene4593.asp

About Us Contact Us Site Map Go ... Genetic Disorders Down's Syndrome Cerebral Palsy Cystic Fibrosis Down Syndrome Sickle Cell Anemia And Genetics ... Spina Bifida Down's syndrome is a genetic disorder. In almost all cases, it is not passed down through families. Instead, it is the result of a single faulty egg or sperm. Persons with Down's syndrome are mentally disabled. They have somewhat flat facial features and slanting eyes. Many affected persons have heart defects and other disorders. The chance of having a baby with Down's syndrome rises as parents get older. It depends more on the mother's age. The chance goes up quickly when the mother is over 34 years. It also goes up when the father is over 60 years of age. This suggests that the main cause of the disorder is the aging of egg cells or exposures, such as radiation or viruses. A young mother who has one child with Down's syndrome has about a 2 in 100 chance of having another. An older mother will continue to have about the same chance that matches her age. The facial signs of Down's syndrome and muscle weakness are usually apparent at birth. By age 1, a baby with Down's syndrome will clearly lag mentally. Their social performance is usually beyond what one would expect from their mental age. They are often socially outgoing and pleasant. They may have defects in the heart, intestines, pelvic bone, and thyroid. They tend to have frequent respiratory infections. They also have an increased risk of leukemia.

24. Facts About Down Syndrome Is down syndrome a rare genetic disorder? down syndrome occurs in 1 in 800 births. Do only older women give birth to babies with down syndrome? http://www.nichd.nih.gov/publications/pubs/downsyndrome/down.htm

Home Search Sitemap Contact ... Publications Facts About Down Syndrome Contents Down syndrome The Chromosomal Basis of Down syndrome The Occurrence of Down syndrome Prenatal Screening and Diagnostic Testing ... Additional Resources for Information on Down syndrome D own Syndrome Named after John Langdon Down, the first physician to identify the syndrome, Down syndrome is the most frequent genetic cause of mild to moderate mental retardation and associated medical problems and occurs in one out of 800 live births, in all races and economic groups. Down syndrome is a chromosomal disorder caused by an error in cell division that results in the presence of an additional third chromosome 21 or "trisomy 21." T he Chromosomal Basis of Down Syndrome To understand why Down syndrome occurs, the structure and function of the human chromosome must be understood. The human body is made of cells; all cells contain chromosomes, structures that transmit genetic information. Most cells of the human body contain 23 pairs of chromosomes, half of which are inherited from each parent. Only the human reproductive cells, the sperm cells in males and the ovum in females, have 23 individual chromosomes, not pairs. Scientists identify these chromosome pairs as the XX pair, present in females, and the XY pair, present in males, and number them 1 through 22.

25. Nutritional Supplements For Down Syndrome down syndrome is a genetic disorder caused by the presence of a third 21st chromosome. It occurs once in every 600 to 700 births, making it the most common http://www.quackwatch.org/01QuackeryRelatedTopics/down.html

Quackwatch Home Page Nutritional Supplements for Down Syndrome: A Highly Questionable Approach Len Leshin, M.D. Down syndrome is a genetic disorder caused by the presence of a third 21st chromosome. It occurs once in every 600 to 700 births, making it the most common genetic disorder. Its common features include poor muscle tone, short stature, a small nose with flat nasal bridge, small skin folds on the inner corner of the eyes (epicanthal folds), dry skin, immune-system suppression, developmental delays, speech difficulties, and mental retardation. Even before Down syndrome was found to be caused by a genetic abnormality, nutritional therapies were proposed, usually focusing on one or two items. Mixtures that included vitamins, hormones and enzymes were advocated in the 1960s by Haboud, a German physician [1]; however, other investigators found no beneficial effect [2]. At about the same time, Henry Turkel, MD, in the United States claimed that a mixture of 48 different ingredients could improve intelligence and the appearance of children with Down syndrome [3]. No double-blind study was ever performed with Turkel's formula. Dr. Turkel administered his formula to children with Down syndrome for almost 40 years; if there had been some benefit, we should have had such evidence by now. Yet no such group of children or adults have been identified to date. In the 1980s, Ruth Harrell, MD, and associates [4] reported that supplementary vitamins and minerals and thyroid hormone improved their IQ scores, and caused "physical changes toward normal" among children with various types of mental deficiency, with the best results in three children with Down syndrome. However, the study was neither controlled nor blinded, and seven different studies during the next decade showed no positive results from Harrell's mixture. Haps Caps, another mixture of vitamins, minerals and enzymes that hit the marketplace during the 1980s, is frequently given with thyroid hormone. No study of Haps Caps has been published.

26. Down Syndrome - MayoClinic.com down syndrome is a genetic disorder that results in mental retardation and other problems. Children with down syndrome benefit from early intervention and http://www.mayoclinic.com/invoke.cfm?id=DS00182

27. Down Syndrome (Trisomy 21) - Lucile Packard Children's Hospital down syndrome is a genetic disorder that includes a combination of birth defects, including some degree of mental retardation, characteristic facial http://www.lpch.org/DiseaseHealthInfo/HealthLibrary/genetics/downs.html

Genetics Clinic Metabolic/Biochemical Genetics Clinic Medical Geneticists Medical Genetics ... Packard Children’s Hospital Pediatrician Receives E. Mead Johnson Award For Pediatric Research Medical Genetics Down Syndrome (Trisomy 21) What are trisomies? The term "trisomy" is used to describe the presence of three chromosomes, rather than the usual pair of chromosomes. For example, if a baby is born with three #21 chromosomes, rather than the usual pair, the baby would be said to have "trisomy 21." Trisomy 21 is also known as Down syndrome. Other examples of trisomy include trisomy 18 and trisomy 13. Again, trisomy 18 or trisomy 13 simply means there are three copies of the #18 chromosome (or of the #13 chromosome) present in each cell of the body, rather than the usual pair. What is Down syndrome? Down syndrome is a genetic disorder that includes a combination of birth defects, including some degree of mental retardation, characteristic facial features and, often, heart defects, visual and hearing impairment, and other health problems. The severity of all of these problems varies greatly among affected individuals. Down syndrome is one of the most common genetic birth defects, affecting approximately one in 800 to 1,000 babies. In this country, there are more than 350,000 individuals with Down syndrome, according to the National Down Syndrome Society. Life expectancy among adults with Down syndrome is about 55 years, though average lifespan varies.

28. Down Syndrome Another relatively rare genetic accident which can cause down syndrome is called While down syndrome is a chromosomal disorder, a baby is usually http://www.chclibrary.org/micromed/00045710.html

Main Search Index Definition Description Causes ... Resources Down syndrome Definition Down syndrome is the most common cause of mental retardation and malformation in a newborn. It occurs because of the presence of an extra chromosome. Description Chromosomes are the units of genetic information that exist within every cell of the body. Twenty-three distinctive pairs, or 46 total chromosomes, are located within the nucleus (central structure) of each cell. When a baby is conceived by the combining of one sperm cell with one egg cell, the baby receives 23 chromosomes from each parent, for a total of 46 chromosomes. Sometimes, an accident in the production of a sperm or egg cell causes that cell to contain 24 chromosomes. This event is referred to as nondisjunction. When this defective cell is involved in the conception of a baby, that baby will have a total of 47 chromosomes. The extra chromosome in Down syndrome is labeled number 21. For this reason, the existence of three such chromosomes is sometimes referred to as Trisomy 21. Causes and symptoms While Down syndrome is a chromosomal disorder, a baby is usually identified at birth through observation of a set of common physical characteristics. Babies with Down syndrome tend to be overly quiet, less responsive, with weak, floppy muscles. Furthermore, a number of physical signs may be present. These include:

29. Down Syndrome Finding Out Your Child Has Down Syndrome down syndrome is a genetic disorder caused by an extra chromosome number 21. It s named after the doctor who discovered its cause. Return to top http://familydoctor.org/338.xml

Advanced Search familydoctor.org Home For Parents Special Conditions in Children Down Syndrome: Finding Out Your Child Has It What is Down syndrome? How is Down syndrome diagnosed? What are the physical signs and birth defects of Down syndrome? Since I learned my baby has Down syndrome, I've been confused and upset. What can I do? ... If I've had one baby with Down syndrome, am I at greater risk of having another? Down Syndrome: Finding Out Your Child Has Down Syndrome Printer-friendly version Email this article What is Down syndrome? Down syndrome is a genetic disorder caused by an extra chromosome number 21. It's named after the doctor who discovered its cause. Return to top How is Down syndrome diagnosed? Tests can be done before birth to find out if a baby has Down syndrome. Tissue and fluid in the womb around the baby can be checked for the extra chromosome. After birth, if the baby has any of the physical signs or birth defects of Down syndrome, the baby's blood can be tested to check for the extra chromosome. Return to top What are the physical signs and birth defects of Down syndrome?

30. Medical References: Down Syndrome down syndrome is one of the most common genetic birth defects, down syndrome is a disorder that includes a combination of birth defects; among them, http://www.marchofdimes.com/professionals/681_1214.asp

View All Chapters Find Your Local Chapter September 20, 2005 Select one Folic Acid Pregnancy Prenatal Screening Infections/Diseases Loss Concerns Newborn Information Birth Defects Polio Genetics Research Funding Perinatal Statistics Medical References Continuing Education ... Prematurity Quick Reference and Fact Sheets Down Syndrome What is Down syndrome? Down syndrome is a disorder that includes a combination of birth defects; among them, some degree of mental retardation, characteristic facial features and, often, heart defects, increased infections, problems with vision and hearing, and other health problems. The severity of all of these problems varies greatly among affected individuals. Down syndrome is one of the most common genetic birth defects, affecting approximately one in 800 to 1,000 babies. It generally is caused by an extra chromosome, the structures in cells that contain the genetic information (genes). According to the National Down Syndrome Society, there are approximately 350,000 individuals with Down syndrome in this country. Life expectancy among adults with Down syndrome is about 55 years, though life span varies depending on the individual and his or her medical condition. What causes Down syndrome?

31. Down Syndrome down syndrome is the most common cause of mental retardation and malformation in a newborn. This form of genetic disorder is called a mosaic. http://www.healthatoz.com/healthatoz/Atoz/ency/down_syndrome.jsp

32. Internet Public Library: Genetic Disorders The Association for Children with down syndrome offers educational, research of Marfan syndrome, a genetic disorder of the connective tissue. http://www.ipl.org/div/aon/browse/hea14.34.00/

dqmcodebase = "/javascript/" Subject Collections Business Computers Education ... Genetic Disorders This collection All of the IPL Advanced Resources in this category: You can also view Subject Collections Magazines under this heading. Association for Children with Down Syndrome http://www.acds.org/ "The Association for Children with Down Syndrome offers educational, therapeutic, behavioral and health-related services to persons with Down Syndrome and their families. Services include pre- and post-natal emotional support for new parents. Social services include, parent education, a community education outreach program and parent advocacy. The early intervention program is designed to optimize each child's ability to become a functioning member of society." ACDS is a non-profit organization and is affiliated with many of the official American Down Syndrome organizations. This is a very good Web resource with many links in the United States as well as more than 60 links all over the world including access to the Down Syndrome listserv and newsgroup. The Information is available in three languages English, German and French. CDGS Family Network, Inc.

33. THE MERCK MANUAL--SECOND HOME EDITION, Down Syndrome In Ch. 266, Chromosomal And down syndrome (trisomy 21) is a chromosomal disorder resulting in mental they more often bear children with down syndrome (see genetic disorders http://www.merck.com/mmhe/sec23/ch266/ch266b.html

var externalLinkWarning = "The link you have selected will take you to a site outside Merck and The Merck Manuals.*n*nThe Merck Manuals do not review or control the content of any non-Merck site. The Merck Manuals do not endorse and are not responsible for the accuracy, content, practices, or standards of any non-Merck sources."; Search The Second Home Edition , Online Version Search Index A B C D ... Z Sections Accidents and Injuries Blood Disorders Bone, Joint, and Muscle Disorders Brain, Spinal Cord, and Nerve Disorders ... Women's Health Issues Resources Anatomical Drawings Multimedia Pronunciations Weights and Measures ... , Online Version Section Children's Health Issues Chapter Chromosomal and Genetic Abnormalities Topics Introduction Down Syndrome Fragile X Syndrome Klinefelter Syndrome Long QT Syndrome Noonan Syndrome ... XYY Syndrome Down Syndrome Buy The Book Print This Topic Email This Topic Pronunciations dementia Down syndrome (trisomy 21) is a chromosomal disorder resulting in mental retardation and physical abnormalities. An extra chromosome, making three of a kind, is called trisomy. The most common trisomy in a newborn is trisomy 21 (three copies of chromosome 21). Trisomy 21 causes about 95% of the cases of Down syndrome. Older mothers, especially those older than 35, contribute an extra chromosome more often than do younger mothers. As a result, they more often bear children with Down syndrome (see

34. THE MERCK MANUAL--SECOND HOME EDITION, Prenatal Diagnostic Testing In Ch. 256, G Some genetic disorders That Can Be Detected Before Birth. disorder (down syndrome is the most common chromosomal abnormality among liveborn babies. http://www.merck.com/mmhe/sec22/ch256/ch256c.html

var externalLinkWarning = "The link you have selected will take you to a site outside Merck and The Merck Manuals.*n*nThe Merck Manuals do not review or control the content of any non-Merck site. The Merck Manuals do not endorse and are not responsible for the accuracy, content, practices, or standards of any non-Merck sources."; Search The Second Home Edition , Online Version Search Index A B C D ... Z Sections Accidents and Injuries Blood Disorders Bone, Joint, and Muscle Disorders Brain, Spinal Cord, and Nerve Disorders ... Women's Health Issues Resources Anatomical Drawings Multimedia Pronunciations Weights and Measures ... , Online Version Section Women's Health Issues Chapter Genetic Disorders Detection Topics Introduction Genetic Screening Prenatal Diagnostic Testing Prenatal Diagnostic Testing Buy The Book Print This Topic Email This Topic Pronunciations alpha-fetoprotein amniocentesis amniotic fluid anencephaly ... umbilical Prenatal diagnostic testing involves testing the fetus before birth (prenatally) to determine whether it has a certain hereditary or spontaneous genetic disorder. The most common tests used to detect abnormalities in a fetus include ultrasonography, chorionic villus sampling, amniocentesis, and percutaneous umbilical blood sampling. Most of these tests are offered primarily to couples with an increased risk of having a baby with a genetic abnormality (particularly neural tube defects) or a chromosomal abnormality (particularly when the woman is aged 35 or older). In the United States, ultrasonography is often performed as part of routine prenatal care.

35. Genetic Disease Information Where can I learn more about different kinds of genetic disorders? down syndrome or trisomy 21 is a common disorder that occurs when a person has three http://www.ornl.gov/sci/techresources/Human_Genome/medicine/assist.shtml

Human Genome Project Information Genomics:GTL Microbial Genome Program home ... skip navigation Genetic Disease Information pronto! Subject Index Send the url of this page to a friend News What's New Meetings Calendar Media Guide Basic Information FAQs Glossary Acronyms Links ... Publications About the Project What is it? Goals Progress History ... Genetics 101 the New Genetics Home Gene Testing Gene Therapy Pharmacogenomics ... Genetic Counseling Ethical, Legal, Social Issues Home Privacy Legislation Gene Testing Patenting ... Genetics in Courtroom Education Teachers Careers Students Webcasts Audio/Video ... Genética Websites en Español Research Home Sequencing Instrumentation Mapping ... Funding Publications Human Genome News Chromosome Poster Primer Molecular Genetics To Know Ourselves ... List of All Publications Search This Site Contact Us Privacy Statement Site Stats and Credits Quick links for this page: What are genetic disorders? Where can I learn more about different kinds of genetic disorders? Why do we have genes that cause genetic disorders? Where can I learn more about genes associated with genetic disorders? ... More Information What are genetic disorders? (1) Single-gene (also called Mendelian or monogenic) Single-gene disorders are inherited in recognizable patterns: autosomal dominant, autosomal recessive, and X-linked. More information on the different modes of inheritance is available from the following Web sites:

36. UNSW Embryo- Abnormal Development - Trisomy 21 (Down Syndrome) Recent attention has focussed on screening for down s syndrome (mainly in genetic counselling will provide current information about the disorder and http://embryology.med.unsw.edu.au/Defect/page21.htm

UNSW Embryology Abnormal Development - Trisomy 21 (Down Syndrome) Acknowledgements Introduction The frequency of trisomy 21 in the population is approximately 1 in 650 to 1,000 live births. The image on the right showns isolated chromosomes from a male trisomy 21 (red arrow shows extra chromosome 21). Recent attention has focussed on screening for Down's syndrome (mainly in terms of cost and efficiency) during fetal life with over 350 articles in the medical literature in just the past five years. There is also a high correlation of increased occurance with an increase in maternal age. ( see table below See also local copy of OMIM List for Trisomy 21 and specific Trisomy 21 entry Mother's Age and Risk of Having a Baby With a Chromosomal Abnormality (see references) Age of Mother Risk of Down Syndrome Risk of Any Chromosomal Abnormality 1 in 1667 1 in 526 1 in 1667 1 in 526 1 in 1429 1 in 500 1 in 1429 1 in 500 1 in 1250 1 in 476 1 in 1250 1 in 476 1 in 1176 1 in 476 1 in 1111 1 in 455 1 in 1053 1 in 435 1 in 1000 1 in 417 1 in 952 1 in 384 1 in 909 1 in 384 1 in 769 1 in 323 1 in 625 1 in 286 1 in 500 1 in 238 1 in 385 1 in 192 1 in 294 1 in 156 1 in 227 1 in 127 1 in 175 1 in 102 1 in 137 1 in 83 1 in 106 1 in 66 1 in 82 1 in 53 1 in 64 1 in 42 1 in 50 1 in 33 1 in 38 1 in 26 1 in 30 1 in 21 1 in 23 1 in 16 1 in 18 1 in 13 1 in 14 1 in 10 1 in 11 1 in 8 References Hook EB.

37. Genetic Disorders To determine the nature of the genetic disorders among these patients, down syndrome, 62, 4.87, 167, 5.37. Metabolic disorder, 52, 4.09, 121, 3.89 http://www.medschool.lsuhsc.edu/genetics_center/louisiana/article_geneticdisorde

Some Genetic Disorders Among Acadian People Yves Lacassie, M.D. Introduction Methods Between November 1986 and December 2000, we evaluated 5,078 patients. Of the 4,569 patients for whom complete demographic information was available, 3,109 were Non-Acadians (68%), 1,272 were Acadians (27.9%), 175 were from other states (3.8%), and 13 were from other countries (0.3%). To determine the nature of the genetic disorders among these patients, we followed standard methodologies commonly used in clinical genetics. However, we would like to emphasize our use of two unique and original methods: (i) the MultiAxial Diagnostic System (MADS), created by Dr. Lacassie more than a decade ago (Lacassie, 1994; Lacassie 2002) and (ii) the novel etiological classification of diagnoses we recently developed (Lacassie, LaMotta, and Florez, 2001). MADS.

38. Medical Genetics - Down Syndrome down syndrome is a genetic disorder that involves a combination of features, including some degree of mental retardation, characteristic facial features and http://www.chkd.org/Genetics/downs.asp

More Health Information Adolescent Medicine Allergy/Immunology Anesthesiology Arthritis Burns Cardiology Craniofacial Dental Medicine Dermatology Developmental Peds Diabetes Digestive Ear, Nose, Throat Genetics Gastroenterology Growth Hematology High Risk Newborn High Risk Pregnancy Infectious Disease Mental Health Neonatology Nephrology Neurology Normal Newborn Normal Pregnancy Oncology Ophthalmology Orthopedics Otolaryngology Pediatric Intensive Care Pediatric Surgery Pediatrics Physical Medicine Plastic Surgery Respiratory/Pulmonology Rheumatology Safety Surgery Terminal Transplant Urology Site Search For a doctor who specializes in this topic, click here. Down Syndrome What are trisomies? The term “trisomy” is used to describe the presence of three chromosomes, rather than the usual pair of chromosomes. For example, if a baby is born with three #21 chromosomes, rather than the usual pair, the baby would be said to have “trisomy 21”. Trisomy 21 is also known as Down syndrome. Other examples of trisomy include trisomy 18 and trisomy 13. Again, trisomy 18 or trisomy 13 simply means there are three copies of the #18 chromosome (or of the #13 chromosome) present in each cell of the body, rather than the usual pair. What is Down syndrome?

39. National Down Syndrome Congress specific genetic syndrome or chromosome disorder such as down syndrome. These advances in prenatal testing of genetic disorders have been accompanied by http://www.ndsccenter.org/aboutUs/ps_prenatal.asp

History Officers and Board of Directors Mission Statements Position Statements Position Statement on Prenatal Screening and Diagnosis There are different types of prenatal testing that can be done to evaluate the risk of a fetus having Down syndrome or determine the diagnosis of Down syndrome. A screening test establishes the risk of a fetus having Down syndrome. It does not provide a definite diagnosis. A diagnostic test studies the chromosomes from the fetus . If there are three copies of chromosome 21, then the baby has Down syndrome. If a fetus is diagnosed with Down syndrome, it is important that the parents are given the opportunity to meet a family which includes a person with Down syndrome. Although some forms of prenatal genetic counseling have been available since the early part of the 20th century, new techniques developed during the past few decades - including amniocentesis, chorionic villus sampling, ultrasound examinations, and various approaches to prenatal screening - have revolutionized intrauterine diagnosis of genetic and chromosome disorders. Since the introduction of these procedures, physicians and genetic counselors have been able to provide more accurate information to many prospective parents regarding the outcomes of pregnancies. Now, instead of discussing general probabilities of risk, the genetic counselor often can tell parents whether the fetus does or does not have a specific genetic syndrome or chromosome disorder such as Down syndrome. These advances in prenatal testing of genetic disorders have been accompanied by numerous moral and ethical concerns.

40. National Down Syndrome Congress down syndrome is a chromosomal disorder characterized by the presence of an extra When this happens, the carrier parent has the normal amount of genetic http://www.ndsccenter.org/qads.asp

about DOWN SYNDROME What is Down syndrome? Down syndrome is a chromosomal disorder characterized by the presence of an extra #21 chromosome. Instead of having 46 chromosomes in each of his/her cells, a person with Down syndrome has 47. The extra chromosome may be derived from either the egg or the sperm. It is believed that during cell division of a sperm or egg, the two #21 chromosomes do not separate properly (nondisjunction). Thus, one cell will have an extra #21 chromosome which later, if united with a normal germ cell which has among others one #21 chromosome, may lead to trisomy 21. The first cell at conception then has 47 chromosomes instead of "normal set" of 46 chromosomes. When this cell with three #21 chromosomes continues to multiply, and the pregnancy is carried to term, a baby with Down syndrome will be born. This form of chromosome error, trisomy 21, is found in about 95% of persons with Down syndrome. The 5 percent of babies with Down syndrome who do not have trisomy 21 may have Translocation, Mosaicism or partial trisomy. In translocation Down syndrome, there are also three copies of the #21 chromosome. However, one of the #21 chromosomes is attached or translocated on another chromosome, usually a #14, #21,or #22 chromosome. Three to four percent of children with Down syndrome have translocation. About one third to one half of translocations are inherited from one of the parents. When this happens, the carrier parent has the normal amount of genetic material, however one of the #21 chromosomes is attached to another chromosome. As a result this individual's total chromosome count is 45 instead of 46. The carrier parent is clinically unaffected because there is no loss or excess of genetic material. Doctors refer to a parent like this as a balanced carrier.

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