In normal people, each cell in the body has 23 pairs of chromosomes. One copy of each pair is inherited from the mother and the other from the father.
Down syndrome (trisomy 21) occurs when a person has an extra copy of chromosome 21 instead of the usual two. This type of Down syndrome accounts for 95% of cases.
What is Down syndrome?
Down syndrome is a genetic condition that causes delays in mental and physical development. It is also associated with an increased risk of medical problems, including heart defects and gastrointestinal abnormalities. Some children with Down syndrome are healthy, while others need more medical attention.
The condition is caused by an extra copy of chromosome 21 (trisomy 21). Chromosomes are bundles of genes that determine how your body develops during pregnancy and after birth. Each cell in the human body has 23 pairs of chromosomes. In most people, one chromosome comes from each parent. When an egg and sperm meet at conception, the child gets 23 chromosomes from both parents.
When something goes wrong during the specialized cell division that makes eggs and sperm, an egg or sperm may have an extra chromosome 21, causing a child to have three copies of chromosome 21 instead of two. Doctors think this happens because the chromosome isn’t dividing properly.
In most cases, there is no link between the chromosome change and anything that the mother or father did or didn’t do before they got pregnant. In a small number of cases, the extra chromosome is transferred from one place on the chromosome to another, called translocation. This type of chromosomal change accounts for about 3% of all people with Down syndrome.
Screening tests are performed before a baby is born to find out if the fetus has a chance of having Down syndrome. They can be done by blood test, ultrasound, or cell-free fetal DNA analysis. These tests are noninvasive, but they do not definitively diagnose Down syndrome.
If you’re thinking about getting pregnant, talk to your doctor about the different prenatal tests available. Some can help you get pregnant sooner, while others are recommended if you are at high risk for Down syndrome.
During pregnancy, your doctor can do an ultrasound to look for signs of Down syndrome, such as the presence of fluid at the back of your uterus. They can also do a blood test to measure the levels of certain proteins and hormones in your blood. If the tests show that your baby is at a higher risk, your doctor may recommend more tests to confirm the diagnosis.
How is it diagnosed?
Down syndrome is caused by an extra chromosome, affecting how the body and brain develop. There are many different ways that Down syndrome can be diagnosed.
Usually it is detected by a screening test, such as a blood test and an ultrasound scan in pregnancy. This test checks if there is an extra chromosome in the baby’s DNA, called trisomy 21, or an extra chromosome that is not part of trisomy 21 (called mosaic Down syndrome).
It is also possible to have one of several other types of Down syndrome. These include translocation Down syndrome, where some of the chromosomes are attached to another one, and Mosaic Down syndrome, where only some of the cells in the body have an extra chromosome.
The most common type of Down syndrome is trisomy 21. In trisomy 21, every cell in the body has three copies of chromosome 21 instead of two. It is more common in babies, but it can occur in adults as well.
People with Down syndrome are more likely to have other health problems, including heart conditions. They may also have problems with their digestive system, eyes and hearing. These can be serious and require treatment, such as surgery to correct them.
In addition, some children with Down syndrome have blood disorders. They may have low iron or anemia, which can affect their ability to get enough oxygen to the rest of their body. They can also have a blood cancer called leukemia.
A screening test can be done as early as the first trimester of pregnancy, or even before then. It involves taking a sample of fluid from the back of the baby’s neck. The fluid is measured to see if there’s more than normal in that area, called “nuchal translucency.”
If the test gives an abnormal result, your doctor will have you wait a few weeks before having a more invasive test for Down syndrome. This is called amniocentesis. The test uses a special machine to remove a small amount of the amniotic fluid from around the baby’s neck.
This procedure has some risks, so it’s usually not done as often as other tests. However, it’s the best way to diagnose Down syndrome and is the most accurate if your baby has it.
What are the symptoms?
Besides humans, other animals can also suffer from genetic disorders. For instance, dogs and cats are prone to birth defects that look like Down syndrome. They also may have mental illnesses that are similar to Down syndrome.
In some cases, apes, including monkeys, can develop down syndrome. It occurs when a baby has an extra copy of chromosome 21 instead of the normal two.
This chromosomal disorder causes a range of physical and mental symptoms in babies, which include short stature, low muscle tone and intellectual disabilities. It also affects the brain, which can make it harder for babies to learn and remember things.
It is a rare condition that can affect humans and other mammals, but it has been observed in chimpanzees and gorillas. The chromosome defect, called trisomy 22, affects only a small percentage of the population.
Kanako, a 24-year-old chimpanzee, is the longest living chimp with down syndrome. She has lived with the chromosomal disorder since she was born in a sanctuary, Kumamoto Sanctuary.
She is blind from cataracts that appeared when she was only one year old and has a congenital heart disease, thinning corneas, underdeveloped teeth and a limited growth rate. She was the second chimpanzee documented to have down syndrome.
In addition to a slowed growth rate, monkeys with down syndrome also experience vision problems and other health issues. These include hypodontia, a condition that involves crooked teeth and underdeveloped jaws.
The condition can affect a baby’s eyes, nose, mouth and ears. It can also cause a wide range of health problems, including heart disease and muscle weakness.
Down syndrome is a chromosomal disorder that causes a baby to have an extra copy of chromosome 21. It can be caused by a single copy of the chromosome or by a combination of three copies.
This chromosomal defect affects a baby’s eyes, nose,mouth and ears. It can also cause a slowed growth rate, a low muscle tone and mental disabilities.
It is a rare condition that can affect adults, too. It is caused by a chromosomal defect that affects the body and the brain. It can result in a variety of health problems, including heart disease and muscle weaknesses.
What are the treatments?
Monkeys are a common target for scientists who need to assess drug safety. Thousands of monkeys are bred and reared in facilities around the world to see how different drugs impact them.
One such animal is Kanako, a 24-year-old chimp from Japan who recently was confirmed to have trisomy 22 (also known as Down syndrome). Her symptoms mimic those found in people with the condition, including vision problems, growth retardation and nystagmus.
While Kanako’s condition is not fully understood, her caretakers say she is generally healthy and does not suffer from mental retardation. They have also been trying to provide her with opportunities for normal social interaction, a key factor in caring for disabled chimps in captivity.
Kanako’s condition was first suspected by news reports from Tanzania last year, where a baby chimp was believed to have Down syndrome but chromosomal tests could not be conducted. It is unclear how common this condition is among chimpanzees, and researchers are trying to understand it better.
Using a variety of methods, Japanese researchers recently found that Kanako had a third duplicate of chromosome 22, which is homologous to chromosome 21 in humans. The chimp, who was born in captivity in 1992, had a number of other health issues as well.
The chromosomal abnormality was confirmed through an analysis of Kanako’s metaphase chromosomes in her blood lymphocytes. She had one extra chromosome, which suggests that her condition is due to a translocation (where one of the chromosomes is attached to a different chromosome during cell division).
In this case, no mosaicism was detected and so full trisomy 17 was assessed. She had several other chromosomal defects, but these were not severe enough to be considered a chromosomal abnormality.
Her behavior was also not impacted by her condition, according to Hirata. She is normally very active and was able to interact with her caretakers until she was 7 years old, when she became blind.
The CDC is offering tecovirimat, which can be given as an oral pill or via a vein, to patients who have had monkeypox and are at high risk of developing a serious illness. The agency also says cidofovir and brincidofovir, two other drugs, can be used to treat people who have had monkeypox. But these medications are often less effective because they haven’t been FDA-approved for use in this situation, and their risks may outweigh the benefits.