Down syndrome is a condition that results in a person having an extra chromosome 21 or an additional piece of the chromosome.Typically, the nucleus of each cell contains 23 parts of chromosomes; half are inherited from each parent. This amorality is the most common chromosomal cause of mild to moderate intellectual disabilities. The additional genetic material alters the course of development causing particular characteristics.Individuals with down syndrome also have distinct physical features, such as a flat face. Upward land in the eyes, low muscle tone, small stature, since deep crease across the center of the palm. These individuals are at risk of developing other health conditions. These traits exist in varying degrees.
How common is down syndrome?
One out of every 691 babies in the United is born with Down Syndrome. Nearly 400,000 Americans have down syndrome; Nearly 6,000 babies are born with down syndrome in the United States every year.
When Was Down Syndrome Discovered?
Historical evidence from art, literature and science alludes to Down syndrome being a condition that has occurred in individuals for centuries. In 1866, John Langdon Down, an English physician published a description of this condition, thus becoming the “father” of Down Syndrome research, In which, the condition was recognized and named after him.
In recent years, advances in medicine have allowed researchers to explore in greater detail the disease and characteristic that it forms. In 1959, A Fench doctor, Jerome Lejeune, identify down syndrome as a chromosomal condition, in which rather than 46 chromosomes present in each cell there are 47 cells in people with Down Syndrome.
Trisomy 21 (Nondisjunction)
The Down Syndrome condition is normally caused by an error in cell division referred to as Nondisjunction. Nondisjunction occurs in an embryo with three copies of chromosome 21 instead of two. Before or at the point of conception, a pair of 21st chromosomes in the sperm or the egg fails to separate. As the embryo develops, the additional hours is replicated in every cell of the body. 95% of cases of Down syndrome are caused by trisomy 21.
Mosaic Down Syndrome is diagnosed when there is a hybrid of two types of cells, some carrying the usual 46 chromosomes and some containing 47, Those cells with 47 choose include an additional 21.
Mosaic is the least common form of Down syndrome, being responsible for 1% of the cases of Down syndrome. The Research has shown that individual with mosaic down syndrome may pose fewer characteristic of Down syndrome than other types of Down syndrome. However, broad generalization is not possible due to a wide range of abilities people with Down syndrome have.
Translocation accounts for about 4% of cases of Down syndrome. The total amount of chromes in the cells remains 46. However, an extra full or partial copy of Chrome open 21 attaches to another chromosome, usually chromosome 14. The appearance of an additional full or partial chromosome 21 causes the characteristic of Down Syndrome.
Cause of Down Syndrome –
Regardless of the type of down syndrome that a person may have, everyone has an extra or additional portion of chromes 21 existing in all or some of his or her cells. This additional genetic material alters the course of development and causes the characters associated with Down syndrome.
It is still unknown what causes the additional full and partial chromosome. Maternal age is the single factor that has been associated with an increased risk of having a baby with Down syndrome emerging from nondisjunction or mosaicism. 80% of children with Down syndrome are born to women under the age of 35. There is no scientific research that indicates any environment factors or parental activities before or during pregnancy that can trigger Down Syndrome.
Down syndrome occurs in people of all races, economic levels. Women have increased the chance of having a child with Down syndrome. A 35-year-old woman has one in 350 chance of reaching a child with Down syndrome. The risk increases gradually to 1 in 100 by age 40. At age 45 the incidence becomes approximately 1 in 20. The age of the mother is not linked to the rinsed of translocation down syndrome.
Since more couples are waiting to until later in life to have children. It is expected that some children born with Down syndrome conceptions are projected to increase. There, genetic counseling is becoming available to more and increasing important. Still, many doctors are not fully informed about advising their patients about the incidences of Down Syndrome.
Does Syndrome Runs in the Family.
All three types of Down syndrome are genetic conditions. However, only 1% of all cases of Down syndrome have a hereditary component ( passed from parent to child through the genes) However, in one-third of cases fo Down syndrome resulting from translocation, there is a heredity component- accounting for about 1% of all cases of Down syndrome.
If a woman has given birth to a baby with trisomy 21 (nondisjunction) or translocation, It is estimated that chance having another a baby with trisomy 21 is 1 in 100 up until age 40.
Down Syndrome Diagnosed?
There are two different area fo testing for Down syndrome that can be epitome been a baby is born: screening testing and diagnostic test. Prenatal screens estimate the chance of the fetus having down Syndrome. These tests do not indicate where you to the water of your fetus has down syndrome, they only provide a probability. A diagnostic test on the other hand, can provide a specific diagnosis with almost 100% accuracy.
There is are an extensive test of prenatal options for prenatal screening test now available of for pregnant women. The most test involves blood test as well as ultrasounds and sonograms. The blood test measures the quantity of various substances in the blood of the mother. The age of women can also is a key indication fo the chances of birthing a child with Down syndrome. The blood test is often performed together with a detailed sonogram to check fo makers, or characteristics that doctors believe have the significant association with Down syndrome. New advance prenatal screens are also able to detect chromosome material from the fetus that is circulating in the maternal blood.
Diagnostics procedures available for prenatal diagnosis of Down Syndrome are chorionic villus Sampling (CVS and amniocentesis). These procedures can carry up to a 1% risk of causing a spontaneous termination (miscarriage), are nearly 100% accurate in diagnosing Down Syndrome. Amniocentesis is usually performed in the second trimesters between 15 and 20 weeks of gestation. CVS is the first trimester between 9 and 14 weeks.
Down syndrome is can be identified at birth by the presence of particular physical traits: Low muscle tone, deep crease across the palm of the hand. A slightly flattened facial profile and an upward slant to the eyes. Since these characteristics can be present in babies without Down system, a chromosomal analysis refers to as a karyotype is done to confirm the diagnosis. To obtain a karyotype, doctors will do a blood sample to examine the baby cells. Photographs chromosomes and then group them by size, number and shape. By examing the karyotype doctors can diagnose down syndrome. Another genetic test called FISH can apply to similar methods and confirm a diagnosis in a shorter amount of time.
Down Syndrome Symptoms
Short stature (height) a child may grow more slowly and be short than average as an adult.
Low Muscle Tone (hypotonia ) through the body, belly muscles with low muscle tone can make the stomach protrude
Short Arms and Legs- Some children have a wide space between the big toe and second toe.
Face Shape and Features
Slanted Eyes – The doctor may notice in the small spots on the iris or colored portion of the eye (iris).
A nasal bridge that looks pushed in. The nasal bridge in the flat area between the noses and the eye.
Smaller Ears- The ears may be set flat or low on the head.
Abnormally- shaped mouth and tongue. The child’s tongue may partly stick out. The roof of the mouth (palate may be narrow and high with a downward curve.
Irregular and crooked teeth – Teeth often come in late and not in the same order that other children’s teeth come in.