They are often slow to turn over, sit, and stand. Developmental delay may be related to the child's weak muscle tone. Development of speech and language may also take longer than expected. Children with Down syndrome may take longer than other children to reach their developmental milestones, but many of these milestones will eventually be met. Showing of 63 View All. Short and broad skull. Short fingers or toes. Depressed bridge of nose.
Flat bridge of nose. Flat nasal bridge. Flat, nasal bridge. Flattened nasal bridge. Low nasal bridge. Low nasal root. Eye folds. Prominent eye folds. Flat facial shape. Mental deficiency. Mental retardation. Mental retardation, nonspecific. Joint instability. Lax joints. Low or weak muscle tone. Decreased length of neck. Thickened skin folds of neck. Thickened skin over the neck.
Upward slanting of the opening between the eyelids. Permanent curving of the pinkie finger. Abnormal fertility. Flat nose. Recessed nasal ridge. Loss of developmental milestones. Mental deterioration in childhood. Downturned corners of the mouth. Downturned mouth. Abnormally large tongue. Increased size of tongue. Large tongue. Decreased width of tooth.
Small mouth. Narrow roof of mouth. Having too much body fat. Gaped jawed appearance. Gaped mouthed appearance. Slack jawed appearance. Precociously senile appearance. Prominent tongue. Tongue sticking out of mouth. Gap between 1st and 2nd toes. Gap between first and second toe.
Increased space between first and second toes. Sandal gap between first and second toes. Wide space between 1st, 2nd toes. Wide space between first and second toes.
Wide-spaced big toe. Widely spaced 1st-2nd toes. Widely spaced first and second toes. Widened gap 1st-2nd toes. Widened gap first and second toe. Decreased length of nose.
Shortened nose. Increased volume of lower lip. Plump lower lip. Prominent lower lip. Enlarged colon lacking nerve cells. Absent anus. Clouding of the lens of the eye. Cloudy lens. Conductive deafness. Conductive hearing loss. Abnormal gait. Abnormal walk. Impaired gait. Underactive thyroid. Decreased pain sensation. Close sighted. Near sighted. Near sightedness. Squint eyes. Noninsulin-dependent diabetes.
Type 2 diabetes. Type II diabetes. Late-onset form of familial Alzheimer disease. Broad hand. Broad hands. Wide palm. Zygomatic flattening. Small ears. Underdeveloped ears. Short middle bone of the little finger. Short middle bone of the pinkie finger. Short middle bone of the pinky finger. Decreased body height. Each year, about 6, babies born in the United States have Down syndrome. This means that Down syndrome occurs in about 1 in every babies.
There are three types of Down syndrome. There are two basic types of tests available to detect Down syndrome during pregnancy: screening tests and diagnostic tests. A screening test can tell a woman and her healthcare provider whether her pregnancy has a lower or higher chance of having Down syndrome. Screening tests do not provide an absolute diagnosis, but they are safer for the mother and the developing baby.
Diagnostic tests can typically detect whether or not a baby will have Down syndrome, but they can be more risky for the mother and developing baby. Neither screening nor diagnostic tests can predict the full impact of Down syndrome on a baby; no one can predict this.
Extra fluid in this region could indicate a genetic problem. Rarely, screening tests can give an abnormal result even when there is nothing wrong with the baby. Sometimes, the test results are normal and yet they miss a problem that does exist. Diagnostic tests are usually performed after a positive screening test in order to confirm a Down syndrome diagnosis. Types of diagnostic tests include:. Mosaicism People with mosaic Down's syndrome have an extra chromosome 21 in only some of their cells.
They therefore have a mixture of trisomic cells and ordinary cells. Depending on the proportion of trisomic cells, and which parts of the body contain these cells, individuals may be less affected both in their physical features and in their ability level than those with regular trisomy or translocation. As for all types of Down's syndrome, it is not possible to say at birth how affected a person will be, only time will tell as the child develops. How does mosaic Down's syndrome happen? Mosaicism arises after the egg and sperm have fused at conception.
As the cells divide and multiply by ordinary cell division, a chromosome goes astray and a single cell with an extra chromosome 21 is formed. This cell continues to divide by ordinary cell division together with the non-trisomic cells and a mixture is produced. As with the other two types of Down's syndrome apart from when a parent is a carrier there is no known reason why mosaic Down's syndrome occurs.
It happens equally often in parents of all ages. What are the chances of having another child with mosaic Down's syndrome? Mosaic Down's syndrome is very rare, therefore there are no accurate figures on this. It is believed that the chance is lower than it would be if the child had regular trisomy Some questions we have been asked Can a test-tube baby have the condition? Yes - full chromosome tests are not carried out before the embryo is implanted. Is trisomy 21 the only kind of trisomy?
Chromosomes 13 and 18 are larger than chromosome 21 and so the genetic imbalance is greater and the effects on the baby are generally more severe than in trisomy Trisomy for the X chromosome or an extra copy of the Y can occur, with relatively few effects for the child. Trisomies of every other chromosome can occur, but usually those pregnancies end in miscarriage.
Parents who have had a baby with one kind of trisomy are not thought to be more likely to have a baby with any other kind of trisomy. Is trisomy much more frequent in miscarriages? Much more. In about half of all miscarriages occuring in the first 3 months of pregnancy, the developing baby has an altered number of chromosomes. Will gene therapy make a difference? As we understand more about how the genes on chromosome 21 interact to cause Down's syndrome, we can imagine a situation in which it might eventually become possible to switch off some of the genes or maybe even the whole extra chromosome responsible for Down's syndrome.
A great deal more understanding of the basic mechanisms of Down's syndrome and a great deal more development in gene therapy is needed before we can contemplate such treatment, but it remains a long-term possibility. Are there any differences in the genes or chromosomes of grandparents of children with Down's syndrome? Unless the grandparent is a carrier of a balanced translocation a very rare event there are no known differences in the genes or chromosomes of grandparents of children with Down's syndrome from those of anyone else's grandparents.
There is nothing known that the grandparents might have done which would explain their grandchild being born with Down's syndrome. Can adults with Down's syndrome have children; and if so, what is the chance of their children having the condition? A woman with Down's syndrome can have children. There have been only a few reports of men with Down's syndrome fathering children. If both partners have Down's syndrome there is a high chance of their children having the condition.
As these events are still rare it is difficult to obtain accurate figures. My grandmother's sister had Down's syndrome. She died 40 years ago when she was Does this mean that I could have an increased chance of having a baby with the condition?
It is unlikely. There is a small chance that she would have had the inherited form of translocation Down's syndrome, in which case you could be a carrier. Chromosome testing was not introduced until so the family may not know what kind of Down's syndrome she had.
If your grandmother had a lot of children and grandchildren and none of them was affected, it is very unlikely that she was a carrier. If you want to be completely sure that you are not a carrier, chromosome test would need to be carried out on your blood.
People with Down's syndrome are all very different from each other, in looks and personality and ability. Why is this, when they all have extra material from chromosome 21? People with Down's syndrome get the extra chromosome material along with the full set of chromosomes from their parents.
All the genes they inherit are ordinary ones, which explains why they resemble their families in the same way as ordinary children. The differences in genes that children with Down's syndrome inherit from their parents, together with differences in their environment, explain the differences between one child with Down's syndrome and another.
Can the tests ever be wrong? If an experienced health professional has seen features of Down's syndrome in your child, and the blood test result shows regular trisomy 21 or a translocation type, there should be no doubt.
In mosaic Down's syndrome, because all the cells in the body do not show trisomy, it is possible for a blood sample not to include any trisomic cells, or to contain only trisomic cells, which may lead to difficulties in arriving at the correct diagnosis. In this situation, while further tests may help, it is not actually possible to disprove mosaicism. Blood tests are done by humans. Mistakes can, of course, be made at one of the many stages that a blood sample passes through before a result is given to the patient.
This, however, is very rare. Cuckle, N. Wald and S. Thompson British Journal of Obstetrics and Gynaecology, vol. Alberman et al. Souvenir Press.
Selikowitz Down Syndrome: The Facts. Oxford University Press. The Genetics of Down's Syndrome This article explains what is known about the genetics of Down's syndrome. Genes therefore control or influence such things as: Our physical appearance The way babies and children grow and develop, even before they are born The timing of the milestones of growth and development The body's supply and use of building and maintenance materials The way the body ages A person's resistance to illness Genes are passed from parents to children.
There are three main types of Down's syndrome: Regular trisomy 21 - also known as standard or free trisomy 21 - in which all the cells have an extra chromosome Translocation - in which extra chromosome 21 material is attached to another chromosome. Mosaic - in which only some of the cells have an extra chromosome Regular Trisomy 21 Most people with Down's syndrome have this type. The chromosomes that can be involved are numbers 13, 14, 15, 21, Because it is a new event, this is sometimes called a de novo translocation.
Genetic counselling should always be available to families with a child with Down's syndrome. Summary Down's syndrome is always caused by the presence of extra chromosome 21 material in a person's cells. There are 3 types of Down's syndrome. Most people with the condition have regular trisomy Much smaller numbers have translocation, or mosaic Down's syndrome. The only way of finding out what type of Down's syndrome people have is to do a blood test and examine their chromosomes under a microscope.
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