The Recognition of Many Types of Family Structures Is Called
What is Down Syndrome?
In every cell in the human 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 forth rod-similar structures chosen chromosomes. Typically, the nucleus of each cell contains 23 pairs of chromosomes, half of which are inherited from each parent. Down syndrome occurs when an individual has a full or partial actress copy of chromosome 21.
This additional genetic textile alters the grade of evolution and causes the characteristics associated with Down syndrome. A few of the common physical traits of Down's syndrome are depression muscle tone, pocket-sized stature, an upward slant to the eyes, and a single deep pucker across the center of the palm – although each person with Downward syndrome is a unique individual and may possess these characteristics to different degrees, or not at all.
How Common is Down's syndrome?
According to the Centers for Disease Command and Prevention, approximately one in every 700 babies in the Usa is born with Downwardly syndrome, making Downwards syndrome the most common chromosomal condition. About half-dozen,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 science. It wasn't until the late nineteenth century, however, that John Langdon Downward, an English doc, published an accurate description of a person with Down's syndrome. It was this scholarly 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 syndrome. In 1959, the French physician Jérôme Lejeune identified Down's syndrome as a chromosomal condition. Instead of the usual 46 chromosomes nowadays in each cell, Lejeune observed 47 in the cells of individuals with Down syndrome. It was subsequently determined that an actress partial or whole copy of chromosome 21 results in the characteristics associated with Down's 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 cracking advances in Downward syndrome research.
Are There Different Types of Down syndrome?
TRISOMY 21 (NONDISJUNCTION)
Down syndrome is usually caused by an error in cell division called "nondisjunction." Nondisjunction results in an embryo with iii 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 separate. As the embryo develops, the actress chromosome is replicated in every cell of the torso. This type 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 contain an extra chromosome 21.
Mosaicism is the least common form of Down syndrome and accounts for but nigh 1% of all cases of Down syndrome. Research has indicated that individuals with mosaic Down syndrome may have fewer characteristics of Down syndrome than those with other types of Downward syndrome. Still, broad generalizations are not possible due to the wide range of abilities people with Downwardly syndrome possess.
TRANSLOCATION
In translocation, which accounts for nigh four% of cases of Down syndrome, the total number of chromosomes in the cells remains 46; yet, an additional total or partial copy of chromosome 21 attaches to another chromosome, normally chromosome 14. The presence of the extra full or partial chromosome 21 causes the characteristics of Downwards syndrome.
What Causes Downwards Syndrome?
Regardless of the blazon of Down syndrome a person may have, all people with Down syndrome have an extra, critical portion of chromosome 21 present in all or some of their cells. This additional genetic cloth alters the course of development and causes the characteristics associated with Down syndrome.
The crusade of the extra total or partial chromosome is even so unknown. Maternal age is the only factor that has been linked to an increased chance of having a babe with Down's syndrome resulting from nondisjunction or mosaicism. However, due to college birth rates in younger women, 80% of children with Down syndrome are built-in to women nether 35 years of age.
At that place is no definitive scientific research that indicates that Down syndrome is acquired past ecology factors or the parents' activities before or during pregnancy.
The additional partial or full re-create of the 21st chromosome which causes Down's syndrome can originate from either the father or the mother. Approximately 5% of the cases have been traced to the father.
Does Downwardly Syndrome Run in Families?
All 3 types of Down syndrome are genetic conditions (relating to the genes), but merely 1% of all cases of Down syndrome have a hereditary component (passed from parent to kid through the genes). Heredity is not a factor in trisomy 21 (nondisjunction) and mosaicism. Notwithstanding, in i-third of cases of Down syndrome resulting from translocation at that place is a hereditary component – accounting for about one% of all cases of Down's syndrome.
The age of the mother does not seem to exist linked to the risk of translocation. Well-nigh cases are desultory – chance – events. Yet, in about i-3rd of cases, 1 parent is a carrier of a translocated chromosome.
What Is the Likelihood of Having a Second Child with Down's syndrome?
One time a woman has given birth to a baby with trisomy 21 (nondisjunction) or translocation, it is estimated that her chances of having another infant with trisomy 21 is 1 in 100 upwardly until historic period 40.
The run a risk of recurrence of translocation is about 3% if the begetter is the carrier and ten-xv% if the mother is the carrier. Genetic counseling can determine the origin of translocation.
How Is Down's syndrome Diagnosed?
PRENATALLY
There are two categories of tests for Down syndrome that tin can be performed before a baby is born: screening tests and diagnostic tests. Prenatal screens judge the chance of the fetus having Downwards syndrome. These tests practice not tell you for sure whether your fetus has Down syndrome; they only provide a probability. Diagnostic tests, on the other hand, can provide a definitive diagnosis with almost 100% accuracy.
There is an extensive menu of prenatal screening tests at present available 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 take chances of having a child with Down's syndrome. These claret tests are often performed in conjunction with a detailed sonogram to bank check for "markers" (characteristics that some researchers feel may have a significant association with Down 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 non invasive (like the diagnostic tests below), but they provide a high accurateness charge per unit. Nonetheless, all of these screens will not definitively diagnose Down's 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 bear up to a 1% adventure of causing a spontaneous termination (miscarriage), are near 100% accurate in diagnosing Down syndrome. Amniocentesis is usually performed in the second trimester betwixt 15 and twenty weeks of gestation, CVS in the first trimester betwixt ix and 14 weeks.
AT BIRTH
Down syndrome is usually identified at nativity past the presence of certain physical traits: low musculus tone, a single deep crease across the palm of the mitt, a slightly flattened facial profile and an upward slant to the eyes. Considering these features may be present in babies without Downwards syndrome, a chromosomal analysis called a karyotype is done to confirm the diagnosis. To obtain a karyotype, doctors draw a claret sample to examine the babe's cells. They photograph the chromosomes and then group them by size, number, and shape. By examining the karyotype, doctors can diagnose Down syndrome. Another genetic examination called FISH can employ similar principles and confirm a diagnosis in a shorter corporeality of time.
Preferred Language Guide
Use this language when referring to Downwards syndrome and people who have Down syndrome:
- People with Down syndrome should always be referred to equally people first.
- Instead of "a Down's syndrome child," it should be "a child with Down's syndrome." Also avoid "Down'south child" and describing the condition as "Down's," as in, "He has Down's."
- Down's syndrome is a condition or a syndrome, not a disease.
- People "accept" Down syndrome, they practice not "endure from" it and are not "afflicted by" it.
- "Typically developing" or "typical" is preferred over "normal."
- "Intellectual disability" or "cerebral disability" has replaced "mental retardation" every bit the appropriate term.
- NDSS strongly condemns the utilise 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's
- NDSS uses the preferred spelling, Down's syndrome, rather than Downward'south syndrome.
- Down syndrome is named for the English md John Langdon Down, who characterized the condition, merely did non accept it. An "apostrophe southward" connotes ownership 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 United states of america is Down syndrome. The AP Stylebook recommends using "Down syndrome," as well.
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
world wide web.brightertomorrows.org
Brighter Tomorrows is a web-based resources for parents who have received a diagnosis of Down Syndrome either prenatally or at birth. The site provides answers to common questions, educates about Down Syndrome and shares the stories of other parents with like situations. - Down's syndrome Pregnancy
www.downsyndromepregnancy.org
This site provides data and back up to expectant parents preparing for the birth of a baby with Down's syndrome.
- International Mosaic Down Syndrome Association
www.imdsa.org
Offers support and resources to families of and individuals with mosaic Down syndrome through the lifespan
- Medline Plus: Wellness Topics – Downward Syndrome
world wide web.nlm.nih.gov/medlineplus/downsyndrome.html
An overview and list of resource on Down syndrome and prenatal testing from Medline Plus, a service of the The states National Library of Medicine and the National Institutes of Wellness
- National Society of Genetic Counselors
world wide web.nsgc.org
Discover members of NSGC through the Find A Genetic Counselor search function
- Understanding a Down syndrome Diagnosis
www.lettercase.org
Agreement a Down's syndrome Diagnosis is an authentic, balanced and upwardly-to-appointment booklet for utilise when delivering a diagnosis of Down Syndrome. It is bachelor equally a costless due east-volume from Lettercase.
DVDS
- Downwards Syndrome: The Starting time 18 Months. Blueberry Shoes Productions.
BOOKS
- A Parent's Guide to Down's syndrome: Toward A Brighter Future. Pueschel, S. (2000). Baltimore, Doc: Brookes Publishing.
- Babies with Down's syndrome: A New Parents' Guide (Third Edition). Skallerup, S. (Ed.) Bethesda, Physician: Woodbine House. (2008)
- Downs: The History of a Disability. Wright, D. New York, NY: Oxford University Press. (2011)
- Tales of Normansfield: The Langdon Downwardly Legacy. Merriman, A. Beccles, UK: The Down's syndrome Association. (2007)
- The Guide to Good Health for Teens and Adults with Downwardly Syndrome. McGuire, D. and Chicoine, B. Bethesda, Md: Woodbine Firm. (2010)
douglasalaire1937.blogspot.com
Source: https://www.ndss.org/about-down-syndrome/down-syndrome/
0 Response to "The Recognition of Many Types of Family Structures Is Called"
Post a Comment