Chances of Down Syndrome With No Family History

Down's syndrome is a condition in which a person has an extra chromosome.

What is Down syndrome?

Down syndrome is a condition in which a person has an actress chromosome. Chromosomes are small "packages" of genes in the body. They determine how a baby's body forms and functions as it grows during pregnancy and afterward nascency. Typically, a infant is born with 46 chromosomes. Babies with Down syndrome have an extra copy of ane of these chromosomes, chromosome 21. A medical term for having an actress copy of a chromosome is 'trisomy.' Down syndrome is besides referred to as Trisomy 21. This actress copy changes how the baby's body and brain develop, which can cause both mental and physical challenges for the baby.

Fifty-fifty though people with Downwards syndrome might act and look similar, each person has different abilities. People with Down's syndrome usually have an IQ (a measure of intelligence) in the mildly-to-moderately low range and are slower to speak than other children.

Some common physical features of Down syndrome include:

• A flattened face, especially the bridge of the nose
• Almond-shaped optics that slant up
• A short neck
• Small-scale ears
• A tongue that tends to stick out of the mouth
• Tiny white spots on the iris (colored role) of the eye
• Small hands and feet
• A unmarried line across the palm of the hand (palmar pucker)
• Small pinky fingers that sometimes bend toward the thumb
• Poor muscle tone or loose joints
• Shorter in height as children and adults

How Many Babies are Born with Down's syndrome?

Down syndrome remains the nigh common chromosomal condition diagnosed in the United States. Each twelvemonth, well-nigh half dozen,000 babies built-in in the Usa have Down's syndrome. This means that Down's syndrome occurs in about ane in every 700 babies.¹

Types of Down Syndrome

In that location are three types of Down syndrome. People often tin can't tell the difference betwixt each type without looking at the chromosomes because the concrete features and behaviors are similar.

• Trisomy 21: Virtually 95% of people with Down syndrome have Trisomy 21.^two With this type of Down syndrome, each cell in the body has 3 carve up copies of chromosome 21 instead of the usual two copies.
• Translocation Downwards syndrome: This blazon accounts for a small pct of people with Down's syndrome (about 3%).² This occurs when an extra part or a whole extra chromosome 21 is present, but information technology is fastened or "trans-located" to a different chromosome rather than existence a carve up chromosome 21.
• Mosaic Down syndrome: This type affects about ii% of the people with Downward syndrome.^two Mosaic means mixture or combination. For children with mosaic Downward syndrome, some of their cells take iii copies of chromosome 21, just other cells have the typical 2 copies of chromosome 21. Children with mosaic Down syndrome may take the same features as other children with Down syndrome. Yet, they may accept fewer features of the condition due to the presence of some (or many) cells with a typical number of chromosomes.

Causes and Risk Factors

• The extra chromosome 21 leads to the physical features and developmental challenges that can occur among people with Down syndrome. Researchers know that Down syndrome is caused past an extra chromosome, simply no ane knows for certain why Down's syndrome occurs or how many different factors play a role.
• One factor that increases the risk for having a baby with Down's syndrome is the female parent's age. Women who are 35 years or older when they become pregnant are more likely to take a pregnancy affected by Down syndrome than women who become pregnant at a younger historic period.^3-5Still, the majority of babies with Down syndrome are born to mothers less than 35 years old, because in that location are many more births among younger women.^vi,vii

Diagnosis

At that place are two basic types of tests available to detect Down syndrome during pregnancy: screening tests and diagnostic tests. A screening examination can tell a adult female and her healthcare provider whether her pregnancy has a lower or college chance of having Down syndrome. Screening tests do non provide an absolute diagnosis, but they are safer for the mother and the developing baby. Diagnostic tests can typically find whether or not a babe will have Downward syndrome, merely they can be more risky for the mother and developing babe. Neither screening nor diagnostic tests can predict the full impact of Down syndrome on a baby; no i tin predict this.

Screening Tests

Screening tests oft include a combination of a blood test, which measures the amount of various substances in the mother's blood (e.g., MS-AFP, Triple Screen, Quad-screen), and an ultrasound, which creates a picture show of the baby. During an ultrasound, one of the things the technician looks at is the fluid backside the baby's neck. Actress fluid in this region could betoken a genetic problem. These screening tests tin can assist determine the baby'south risk of Downwardly syndrome. Rarely, screening tests can give an aberrant result even when there is nil incorrect with the baby. Sometimes, the exam results are normal and yet they miss a problem that does be.

Diagnostic Tests

Diagnostic tests are usually performed after a positive screening exam in order to confirm a Down's syndrome diagnosis. Types of diagnostic tests include:

• Chorionic villus sampling (CVS)—examines material from the placenta
• Amniocentesis—examines the amniotic fluid (the fluid from the sac surrounding the baby)
• Percutaneous umbilical blood sampling (PUBS)—examines blood from the umbilical cord

These tests await for changes in the chromosomes that would bespeak a Downward syndrome diagnosis.

Other Health Issues

Many people with Down syndrome accept the common facial features and no other major birth defects. However, some people with Down's syndrome might have ane or more major nativity defects or other medical problems. Some of the more mutual health problems among children with Down syndrome are listed below.⁸

• Hearing loss
• Obstructive sleep apnea, which is a status where the person'south animate temporarily stops while comatose
• Ear infections
• Eye diseases
• Center defects present at birth

Health care providers routinely monitor children with Down's syndrome for these conditions.

Treatments

Down syndrome is a lifelong status. Services early in life volition often help babies and children with Down syndrome to improve their concrete and intellectual abilities. Most of these services focus on helping children with Down syndrome develop to their full potential. These services include speech, occupational, and physical therapy, and they are typically offered through early on intervention programs in each state. Children with Down's syndrome may as well demand extra help or attention in schoolhouse, although many children are included in regular classes.

Other Resource

The views of these organizations are their own and do non reflect the official position of CDC.

• Down Syndrome Research Foundation (DSRF)external icon
  DSRF initiates enquiry studies to meliorate sympathize the learning styles of those with Down syndrome.
• Global Down's syndrome Foundationexternal icon
  This foundation is defended to significantly improving the lives of people with Down syndrome through research, medical care, pedagogy and advocacy.
• National Association for Down's syndromeexternal icon
  The National Association for Downwards Syndrome supports all persons with Down syndrome in achieving their full potential. They seek to help families, educate the public, address social issues and challenges, and facilitate active participation.
• National Downwards Syndrome Society (NDSS)external icon
  NDSS seeks to increment awareness and acceptance of those with Down syndrome.

References

1. Mai CT, Isenburg JL, Canfield MA, Meyer RE, Correa A, Alverson CJ, Lupo PJ, Riehle‐Colarusso T, Cho SJ, Aggarwal D, Kirby RS. National population‐based estimates for major birth defects, 2010–2014. Birth Defects Enquiry. 2019; 111(xviii): 1420-1435.
2. Shin M, Siffel C, Correa A. Survival of children with mosaic Down syndrome. Am J Med Genet A. 2010;152A:800-1.
3. Allen EG, Freeman SB, Druschel C, et al. Maternal age and take a chance for trisomy 21 assessed past the origin of chromosome nondisjunction: a report from the Atlanta and National Down Syndrome Projects. Hum Genet. 2009 Feb;125(1):41-52.
4. Ghosh S, Feingold E, Dey SK. Etiology of Down syndrome: Evidence for consistent association among altered meiotic recombination, nondisjunction, and maternal age across populations. Am J Med Genet A. 2009 Jul;149A(seven):1415-20.
5. Sherman SL, Allen EG, Bean LH, Freeman SB. Epidemiology of Down syndrome. Ment Retard Dev Disabil Res Rev. 2007;13(3):221-7.
6. Adams MM, Erickson JD, Layde PM, Oakley GP. Down'due south syndrome. Contempo trends in the United States. JAMA. 1981 Aug fourteen;246(7):758-60.
7. Olsen CL, Cantankerous PK, Gensburg LJ, Hughes JP. The effects of prenatal diagnosis, population ageing, and changing fertility rates on the live birth prevalence of Down's syndrome in New York Land, 1983-1992. Prenat Diagn. 1996 November;16(11):991-1002.
8. Bull MJ, the Committee on Genetics. Health supervision for children with Down syndrome. Pediatrics. 2011;128:393-406.

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Source: https://www.cdc.gov/ncbddd/birthdefects/downsyndrome.html

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