Why Are So Many Babies Born With Down Syndrome

What is Downward Syndrome?

In every jail cell in the human being body there is a nucleus, where genetic material is stored in genes. Genes carry the codes responsible for all of our inherited traits and are grouped along rod-similar structures called chromosomes. Typically, the nucleus of each prison cell contains 23 pairs of chromosomes, one-half of which are inherited from each parent. Down's syndrome occurs when an individual has a total or partial extra copy of chromosome 21.

This additional genetic material alters the form of development and causes the characteristics associated with Down's syndrome. A few of the common physical traits of Down syndrome are low muscle tone, small stature, an up slant to the eyes, and a single deep pucker across the eye of the palm – although each person with Down syndrome is a unique private and may possess these characteristics to different degrees, or non at all.

How Common is Down syndrome?

Co-ordinate to the Centers for Illness Control and Prevention, approximately one in every 700 babies in the United States is born with Downwards syndrome, making Downwardly syndrome the most common chromosomal condition. Nearly 6,000 babies with Down syndrome are born in the The states each year.

When Was Down's syndrome Discovered?

For centuries, people with Down syndrome have been alluded to in art, literature and scientific discipline. It wasn't until the late nineteenth century, however, that John Langdon Down, an English physician, published an accurate description of a person with Down syndrome. It was this scholarly piece of work, published in 1866, that earned Down the recognition as the "father" of the syndrome. Although other people had previously recognized the characteristics of the syndrome, it was Downwardly who described the condition as a distinct and separate entity.

In recent history, advances in medicine and science have enabled researchers to investigate the characteristics of people with Down's syndrome. In 1959, the French physician Jérôme Lejeune identified Down syndrome as a chromosomal condition. Instead of the usual 46 chromosomes present in each cell, Lejeune observed 47 in the cells of individuals with Down syndrome. It was later determined that an extra partial or whole re-create of chromosome 21 results in the characteristics associated with Down syndrome. In the year 2000, an international team of scientists successfully identified and catalogued each of the approximately 329 genes on chromosome 21. This accomplishment opened the door to great advances in Down's syndrome research.

Are At that place Different Types of Down syndrome?

TRISOMY 21 (NONDISJUNCTION)

Down syndrome is commonly caused by an error in cell sectionalisation chosen "nondisjunction." Nondisjunction results in an embryo with three copies of chromosome 21 instead of the usual two. Prior to or at formulation, a pair of 21st chromosomes in either the sperm or the egg fails to split. As the embryo develops, the actress chromosome is replicated in every cell of the trunk. This blazon of Down syndrome, which accounts for 95% of cases, is called trisomy 21.

MOSAICISM

Mosaicism (or mosaic Down syndrome) is diagnosed when there is a mixture of two types of cells, some containing the usual 46 chromosomes and some containing 47. Those cells with 47 chromosomes incorporate an extra chromosome 21.

Mosaicism is the least common form of Down syndrome and accounts for merely almost 1% of all cases of Down's syndrome. Research has indicated that individuals with mosaic Down syndrome may have fewer characteristics of Downward syndrome than those with other types of Down syndrome. Yet, broad generalizations are not possible due to the wide range of abilities people with Down's syndrome possess.

TRANSLOCATION

In translocation, which accounts for about 4% of cases of Down syndrome, the total number of chromosomes in the cells remains 46; even so, an boosted full or fractional re-create of chromosome 21 attaches to another chromosome, unremarkably chromosome 14. The presence of the actress full or fractional chromosome 21 causes the characteristics of Down's syndrome.

What Causes Down syndrome?

Regardless of the type of Down syndrome a person may take, all people with Down's syndrome take an extra, critical portion of chromosome 21 present in all or some of their cells. This boosted genetic material alters the course of development and causes the characteristics associated with Down's syndrome.

The cause of the extra total or fractional chromosome is however unknown. Maternal historic period is the only factor that has been linked to an increased run a risk of having a babe with Down's syndrome resulting from nondisjunction or mosaicism. Still, due to higher birth rates in younger women, fourscore% of children with Down syndrome are born to women nether 35 years of historic period.

There is no definitive scientific enquiry that indicates that Downwards syndrome is acquired by environmental factors or the parents' activities before or during pregnancy.

The boosted partial or total copy of the 21st chromosome which causes Down syndrome can originate from either the father or the mother. Approximately five% of the cases have been traced to the begetter.

Does Downwards Syndrome Run in Families?

All 3 types of Down's syndrome are genetic weather (relating to the genes), only just 1% of all cases of Down syndrome have a hereditary component (passed from parent to child through the genes). Heredity is not a factor in trisomy 21 (nondisjunction) and mosaicism. However, in one-3rd of cases of Down's syndrome resulting from translocation there is a hereditary component – accounting for most ane% of all cases of Down's syndrome.

The age of the mother does not seem to be linked to the take chances of translocation. Near cases are sporadic – chance – events. However, in about one-tertiary of cases, i parent is a carrier of a translocated chromosome.

What Is the Likelihood of Having a 2d Child with Down Syndrome?

In one case a woman has given birth to a babe with trisomy 21 (nondisjunction) or translocation, it is estimated that her chances of having another baby with trisomy 21 is 1 in 100 upwards until age 40.

The risk of recurrence of translocation is virtually three% if the begetter is the carrier and 10-15% if the mother is the carrier. Genetic counseling can determine the origin of translocation.

How Is Downward Syndrome Diagnosed?

PRENATALLY

There are ii categories of tests for Down's syndrome that can exist performed before a baby is born: screening tests and diagnostic tests. Prenatal screens estimate the hazard of the fetus having Down syndrome. These tests practice non tell you for sure whether your fetus has Down syndrome; they simply provide a probability. Diagnostic tests, on the other hand, tin provide a definitive diagnosis with almost 100% accuracy.

There is an all-encompassing menu of prenatal screening tests now bachelor for pregnant women. Most screening tests involve a blood exam and an ultrasound (sonogram). The blood tests (or serum screening tests) measure quantities of various substances in the blood of the mother. Together with a woman's age, these are used to estimate her chance of having a child with Down's syndrome. These blood tests are often performed in conjunction with a detailed sonogram to bank check for "markers" (characteristics that some researchers feel may have a meaning association with Down's syndrome). New advanced prenatal screens are at present able to detect chromosomal material from the fetus that is circulating in the maternal blood. These tests are not invasive (like the diagnostic tests below), but they provide a loftier accuracy rate. Still, all of these screens volition not definitively diagnose Down syndrome. Prenatal screening and diagnostic tests are now routinely offered to women of all ages.

The diagnostic procedures bachelor for prenatal diagnosis of Down syndrome are chorionic villus sampling (CVS) and amniocentesis. These procedures, which deport up to a 1% risk of causing a spontaneous termination (miscarriage), are virtually 100% authentic in diagnosing Down syndrome. Amniocentesis is usually performed in the second trimester between xv and 20 weeks of gestation, CVS in the showtime trimester between 9 and fourteen weeks.

AT BIRTH

Down syndrome is ordinarily identified at nascence by the presence of certain concrete traits: low musculus tone, a single deep crease across the palm of the hand, a slightly flattened facial profile and an upward slant to the eyes. Because these features may be present in babies without Down syndrome, a chromosomal assay called a karyotype is done to confirm the diagnosis. To obtain a karyotype, doctors draw a blood sample to examine the infant's cells. They photograph the chromosomes so group them past size, number, and shape. By examining the karyotype, doctors tin diagnose Down's syndrome. Some other genetic examination chosen FISH can utilise similar principles and confirm a diagnosis in a shorter amount of time.

Preferred Linguistic communication Guide

Utilise this language when referring to Down's syndrome and people who have Down's syndrome:

• People with Down syndrome should always be referred to as people offset.
• Instead of "a Down syndrome child," it should be "a child with Down syndrome." As well avoid "Downwards's child" and describing the condition equally "Down'due south," as in, "He has Down'due south."
• Down syndrome is a condition or a syndrome, not a disease.
• People "have" Down's syndrome, they practise non "suffer from" it and are not "afflicted by" information technology.
• "Typically developing" or "typical" is preferred over "normal."
• "Intellectual disability" or "cognitive inability" has replaced "mental retardation" equally the appropriate term.
• NDSS strongly condemns the use of the word "retarded" in any derogatory context. Using this word is hurtful and suggests that people with disabilities are not competent.

Down vs. Down'southward

• NDSS uses the preferred spelling, Down's syndrome, rather than Down's syndrome.
• Down's syndrome is named for the English doctor John Langdon Down, who characterized the condition, but did not accept it. An "apostrophe s" connotes buying or possession.
• While Down syndrome is listed in many dictionaries with both pop spellings (with or without an apostrophe s), the preferred usage in the U.s.a. is Down's syndrome. The AP Stylebook recommends using "Down syndrome," as well.

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These downloadable versions of the Preferred Language Guide are available to print and distribute:

• NDSS Preferred Language Guide
• NDSS Fact Sheet and Language Guide

Resources

EXTERNAL Resources

• Brighter Tomorrows
  www.brightertomorrows.org
  Brighter Tomorrows is a web-based resource for parents who have received a diagnosis of Down's syndrome either prenatally or at nascence. The site provides answers to common questions, educates about Down syndrome and shares the stories of other parents with similar situations.
• Down Syndrome Pregnancy
  www.downsyndromepregnancy.org
  This site provides data and support to expectant parents preparing for the birth of a baby with Down syndrome.

• International Mosaic Down syndrome Association
  world wide web.imdsa.org
  Offers support and resource to families of and individuals with mosaic Down syndrome through the lifespan

• Medline Plus: Health Topics – Downwardly Syndrome
  www.nlm.nih.gov/medlineplus/downsyndrome.html
  An overview and listing of resources on Down syndrome and prenatal testing from Medline Plus, a service of the Usa National Library of Medicine and the National Institutes of Health

• National Society of Genetic Counselors
  www.nsgc.org
  Observe members of NSGC through the Find A Genetic Counselor search function

• Understanding a Downwardly Syndrome Diagnosis
  www.lettercase.org
  Agreement a Downwardly Syndrome Diagnosis is an accurate, balanced and up-to-date booklet for use when delivering a diagnosis of Down syndrome. It is available every bit a free e-book from Lettercase.

DVDS

• Down syndrome: The Kickoff eighteen Months. Blueberry Shoes Productions.

BOOKS

• A Parent's Guide to Down Syndrome: Toward A Brighter Future. Pueschel, S. (2000). Baltimore, MD: Brookes Publishing.
• Babies with Down's syndrome: A New Parents' Guide (Third Edition). Skallerup, S. (Ed.) Bethesda, Md: Woodbine House. (2008)
• Downs: The History of a Disability. Wright, D. New York, NY: Oxford Academy Press. (2011)
• Tales of Normansfield: The Langdon Down Legacy. Merriman, A. Beccles, UK: The Downwardly'south Syndrome Association. (2007)
• The Guide to Expert Health for Teens and Adults with Down syndrome. McGuire, D. and Chicoine, B. Bethesda, MD: Woodbine House. (2010)

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Source: https://www.ndss.org/about-down-syndrome/down-syndrome/

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