About half of all affected children are born with a heart defect. Digestive abnormalities, such as a blockage of the intestine, are less common. Individuals with Down syndrome have an increased risk of developing several medical conditions.
These include gastroesophageal reflux, which is a backflow of acidic stomach contents into the esophagus, and celiac disease , which is an intolerance of a wheat protein called gluten. About 15 percent of people with Down syndrome have an underactive thyroid gland hypothyroidism. The thyroid gland is a butterfly-shaped organ in the lower neck that produces hormones.
Individuals with Down syndrome also have an increased risk of hearing and vision problems. Additionally, a small percentage of children with Down syndrome develop cancer of blood-forming cells leukemia. Delayed development and behavioral problems are often reported in children with Down syndrome. Affected individuals can have growth problems and their speech and language develop later and more slowly than in children without Down syndrome.
Additionally, speech may be difficult to understand in individuals with Down syndrome. A small percentage of people with Down syndrome are also diagnosed with developmental conditions called autism spectrum disorders, which affect communication and social interaction. People with Down syndrome often experience a gradual decline in thinking ability cognition as they age, usually starting around age Down syndrome is also associated with an increased risk of developing Alzheimer disease , a brain disorder that results in a gradual loss of memory, judgment, and ability to function.
Approximately half of adults with Down syndrome develop Alzheimer disease. Although Alzheimer disease is usually a disorder that occurs in older adults, people with Down syndrome commonly develop this condition earlier, in their fifties or sixties. Down syndrome occurs in about 1 in newborns.
About 5, babies with Down syndrome are born in the United States each year, and approximately , people in this country have the condition. Although women of any age can have a child with Down syndrome, the chance of having a child with this condition increases as a woman gets older. Most cases of Down syndrome result from trisomy 21 , which means each cell in the body has three copies of chromosome 21 instead of the usual two copies.
Less commonly, Down syndrome occurs when part of chromosome 21 becomes attached translocated to another chromosome during the formation of reproductive cells eggs and sperm in a parent or very early in fetal development.
Affected people have two normal copies of chromosome 21 plus extra material from chromosome 21 attached to another chromosome, resulting in three copies of genetic material from chromosome Affected individuals with this genetic change are said to have translocation Down syndrome. A very small percentage of people with Down syndrome have an extra copy of chromosome 21 in only some of the body's cells. In these people, the condition is called mosaic Down syndrome. Researchers believe that having extra copies of genes on chromosome 21 disrupts the course of normal development, causing the characteristic features of Down syndrome and the increased risk of health problems associated with this condition.
Most cases of Down syndrome are not inherited. It's also known as Edwards syndrome, named after the physician who first diagnosed the condition. Like Down syndrome, trisomy 18 usually occurs because of a random genetic event rather than an inherited condition. Trisomy 18 is more life-threatening than Down syndrome. Before they're born, babies with trisomy 18 experience a slow growth rate as well as heart defects and other organ abnormalities.
According to the National Institutes of Health , once born, they also tend to have a low birth weight, "small, abnormally-shaped head, small jaw and mouth, and clenched fists with overlapping fingers. Severe medical problems caused by heart defects and organ abnormalities threaten their lives from the very beginning.
Sadly, most babies with trisomy 18 die before birth or within their first month of life. Only "five to 10 percent of children with this condition live past their first year, and these children often have severe intellectual disability," according to NIH sources. An extra copy of chromosome 13 causes trisomy 13, also known as Patau syndrome. As with Down syndrome and trisomy 18, trisomy 13 usually occurs due to a random genetic event.
Babies with trisomy 13 are born with life-threatening medical conditions, including severe intellectual disabilities and terrible physical abnormalities.
According to Genetic and Rare Diseases Information Center GARD , they usually have heart defects, brain or spinal cord irregularities, very small or poorly developed eyes, extra fingers or toes, a cleft lip, cleft palate, and weak muscle tone.
Sadly, babies with trisomy 13 often die within their first few days or weeks of life. Only five to ten percent of babies with trisomy 13 will live past their first birthday, says GARD.
Trisomy 13 has the same risk factors as Down syndrome and trisomy 18, and advanced maternal age is the biggest predictor of the condition. With so many frightening abnormalities associated with trisomies, it's only natural to want to know whether there is a risk that your baby is born with one of these conditions. NTD Eurofins offers several non-invasive prenatal screening tests. Each can tell you whether you're at a greater risk for the three types of trisomy.
With the prenatal screening test Verifi , your OB will draw a sample of your blood as early as 10 weeks into your pregnancy. The test will then analyze the DNA present in your blood and is capable of determining how many chromosomes are present.
This test requires a sample of your blood, in addition to an ultrasound performed by your OB sometime between nine and 13 weeks into your pregnancy. During this ultrasound, your OB will also check for fluid accumulation behind your baby's neck, which can indicate Down syndrome.
The First Trimester Prenatal Screen analyzes the amount of alpha-fetoprotein, free beta hCG, and pregnancy-associated plasma protein-A in your blood. Humans usually have 23 pairs of chromosomes, with two sex chromosomes that determine sex and 44 chromosomes that direct other factors, such as growth and function. A chromosome condition is caused by an alteration in the number or genetic structure of chromosomes.
This means they have 47 chromosomes instead of Down syndrome, Edward syndrome and Patau syndrome are the most common forms of trisomy. Children affected by trisomy usually have a range of birth anomalies, including delayed development and intellectual disabilities. The addition of an extra chromosome usually occurs spontaneously during conception.
The cause of this is unknown and prevention is not possible. The most important risk factor for trisomy conditions is maternal age. Women in their late 30s and 40s have a higher chance of trisomy conditions occurring. In Victoria, Down syndrome affects about one in pregnancies. Down syndrome is also known as Trisomy 21, because the person has three copies of chromosome 21 instead of two. There are three types of Down syndrome. In Mosaic Down syndrome, the extra chromosome spontaneously appears as the embryo develops.
Translocation Down syndrome, which accounts for approximately five per cent of cases, is inheritable. Some of the physical characteristics of Down syndrome may include:. All people with Down syndrome will experience some delay in their development and some level of learning disability.
Learn more about Down syndrome. In Victoria, Edward syndrome affects about one in 1, pregnancies. Edward syndrome is also known as Trisomy 18, because the person has three copies of chromosome 18 instead of two. Some of the characteristics of Edward syndrome may include:. In Victoria, Patau syndrome affects around one in 3, pregnancies. Patau syndrome is also known as Trisomy 13, because the person has three copies of chromosome 13 instead of two.
Some of the characteristics of Patau syndrome may include:. Sometimes, signs of trisomy conditions may be evident during the pregnancy.
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