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|Down Syndrome Facts
Down syndrome is a chromosomal disorder (mostly they have too many chromosomes in their cells) which a baby is born with. It results in a variety of health problems as well a characteristic facial appearance. People with Down syndrome suffer different degrees of severity in symptoms ranging from intellectual disabilities, heart defects, thyroid issues, digestive problems like celiac disease or gastroesophageal reflux and other health problems. Given the increased risk of developing significant medical problems, the life expectancy of someone with Down syndrome is about 50, significantly lower than the national average of a 'normal' person. Yet, many adults with Down syndrome have jobs and live independently. Down syndrome affects one in every 800 babies born in the United States each year, and according to the National Down Syndrome Society, there are currently more than 400,000 people living with the disorder in America. In general, Down syndrome is not one of those inherited genetic disorders but rather the result of a random event during the formation of the cells during conception.
A child born with this chromosomal disorder will have a characteristic appearance:
• Eyes slant upwards.
This disorder is caused by extra genetic material from chromosome 21. Each person normally has 23 pairs of chromosomes (46 in total). One half of the chromosomes come from the father, and the other half from the mother. On occasion however, something goes wrong before fertilization. Sometimes the egg or sperm divide incorrectly, resulting in an extra chromosome 21, which means the resulting embryo ends up with 47 chromosomes instead of 46 (nondisjunction). This process of nondisjunction seems to occur more frequently in older women. It may explain why the risk of having a baby with Down syndrome is greater among women experiencing a pregnancy after 35 and older. Down syndrome is also called trisomy 21 because the individuals end up with three chromosomes 21 instead of the usual two. This type of cell division error causes the vast majority of Down syndrome cases (95 percent). In 3 to 4 percent of cases an embryo may have what is called translocation Down syndrome. This is where part of chromosome 21 breaks off before fertilization and attaches itself to another chromosome. It means the baby will have 2 normal copies of chromosome 21, plus extra chromosome 21 material attached to another chromosome. Finally in 1 to 2 percent of cases, the individuals have a form of Down syndrome called Mosaicism. This is where a cell division error happens after fertilization and the baby ends up with some cells with the two regular chromosomes 21 and others with the abnormal numbers.
Prevention: The best way to reduce the risk factors of having a baby with Down syndrome is to follow a good prenatal care guide, and to start preparing for pregnancy before you even become pregnant. Genetic counselors will also help you assess your personal risk profile.
Yes. The risks increase incrementally with age, but the most significant increases are after the age of 35. Interestingly enough however, 80 percent of babies born with Down syndrome are born to mothers under 35. This is because statistically a younger woman is likely to have more babies than an older woman.
Yes. The American College of Obstetricians and Gynecologists (ACOG) recommend that all pregnant women in their first trimester be tested for Down syndrome, regardless of the woman's age. The first test can be carried out in weeks 11 to 13 of pregnancy. This is a maternal blood test in addition to a special ultrasound scan which measures the thickness at the back of the baby's head (called nuchal scan). It can also be carried out in the second trimester at weeks 15 to 20 without ultrasound. Women who have abnormal results from these screenings will then be offered a diagnostic test such as amniocentesis or chorionic villus sampling. These tests are highly accurate when it comes to diagnosing Down syndrome. If you are planning to conceive a child by IVF, then pre-implantation genetic diagnosis can help detect Down syndrome before the embryo is even implanted.
The degree of intellectual difficulties a child born with Down syndrome will experience cannot be predicted at birth, and will only manifest as the child grows older. In general disabilities range from mild to moderate, and with proper intervention few develop severe disabilities. Children with Down syndrome can do can do most things any young child can do, including talking, walking, dressing and being potty-trained. They may just take a little longer, or learn these things later. If you have questions on any other female health topic, see our section womens health questions.
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