In most cells, inherited information is stored in a rod-like structure called chromosomes. Most people have 23 pairs of chromosomes—one pair from each parent. Down syndrome happens when a fetus has an extra copy of chromosome 21.
Children with Down syndrome need regular doctor visits and may require special tests and exams. Their care teams usually include medical specialists (like a cardiologist or endocrinologist) and physical, speech and occupational therapists.
Trisomy 21
Down Syndrome is a genetic disorder caused by an extra copy of chromosome 21. This extra chromosome can affect cognitive development and lead to learning disabilities. It also increases the risk of certain health problems, including autoimmune disorders and heart disease.
Monkeys can inherit an extra chromosome from their parents, but the condition is much less common in monkeys than humans. A few animals have been diagnosed with Down Syndrome, but most have normal chromosomes. These cases may help scientists understand the causes of the disorder and how it develops.
Researchers have recently discovered a chimpanzee named Kanako who has a version of Down Syndrome similar to that of humans. She was born with stunted growth and has cross eyes, a heart defect, and congenital cataracts. She also has an abnormally high level of amyloid beta peptide, which is associated with Alzheimer’s disease. The chimp’s caretakers did not suspect she had Down Syndrome until she turned one year old and started having vision problems.
In contrast to the first chimpanzee with Down Syndrome, who died in 1969, Kanako is living a long life. She is the longest-living chimpanzee known to have Down Syndrome and she has lived to be 24 years old. Her case reveals that there is hope for people with Down Syndrome who have a family history of the disease.
While the majority of cases of Down Syndrome are attributed to nondisjunction in the maternal gamete, there are also instances where trisomy 21 can result from balanced translocation or mosaicism. Mosaicism is where the extra chromosome comes from both the mother and father’s cells during cellular division. It is thought that a maternal uniparental disomy of chromosome 21 is responsible for approximately 95% of cases of Down Syndrome and that this number increases with maternal age.
A study of 104 individuals with Down Syndrome found that those with low-level mosaicism had a better prognosis than those with complete non-mosaic Down Syndrome. The authors suggest that this may be due to a reduced risk of transmission of the disease from affected parents to their offspring, in contrast to the increased risk of transmission in those with complete non-mosaic Down syndrome.
Mosaicism
Mosaicism is a type of non-Mendelian inheritance. It involves a mix of cells with different chromosomes, and may cause disease that can be traced to the cellular level, such as cancer or Down syndrome. Mosaicism can be caused by errors that occur during cell division, which occurs constantly throughout a person’s life. It can also be the result of certain pregnancies, such as those that end in miscarriage or birth defects.
Mosaicism can be detected by testing a sample of DNA from blood or cheek swabs. A doctor can then look at the chromosomes and determine whether or not the individual has mosaicism. If they do, the physician can tell how much of the body’s cells have a particular chromosome, usually in percentage terms. If, for example, fifteen out of twenty cells have an extra chromosome 21, then the person would have 75 percent of Down syndrome.
Typically, mosaic Down syndrome is caused by an error in cell division that happens early in the development of a fetus. It is not known exactly how this error occurs, but it has been suggested that maternal age might play a role. Mosaic Down syndrome is characterized by an extra copy of chromosome 21. This can be detected by comparing the chromosomes of the patient’s cells to those of a healthy individual.
Another common form of mosaicism is found in Turner’s syndrome. This is due to a mistake in cell division that gives some cells an extra chromosome, while other cells have the normal chromosome. This can be detected by analyzing a sample of DNA from a blood or cheek swab, and can be described as having a 46,X/46,XX karyotype, which is typical for both females and males.
Genetic mosaicism can be a sign of chromosome abnormalities such as Down syndrome or other diseases, but the effects can vary from person to person. The severity of the disease and how many cells are affected will depend on how and when the error occurred. For example, if the mistake happened early in embryonic development, then more than 50 percent of cells could be abnormal, resulting in a high level of mosaicism. If the mistake occurs later, then fewer cells will be abnormal, and the impact is usually less severe.
Translocation
In genetics, a translocation is a change in the structure of a chromosome by having pieces of chromosomes trade places with each other. This is usually not a problem, but in some cases it can lead to a variety of medical problems, including Down syndrome. In Down syndrome, the 21 chromosome gets attached to other chromosomes, resulting in three 21 chromosomes and one normal chromosome. This is called trisomy 21, and it causes the health issues associated with Down syndrome.
Some chromosomal changes, such as translocations and inversions, may occur randomly, while others are caused by environmental factors, such as radiation exposure or infections. These changes can have a dramatic effect on a person’s health. Some examples of chromosomal mutations include deletion, mutations in the X or Y chromosomes and chromosomal rearrangements, such as Robertsonian translocations.
Robertsonian translocations are chromosomal abnormalities in which a segment of chromosome 13 and 14 fuse with a segment of chromosome 21. These abnormalities are rare and affect only a small percentage of the population. However, heterozygotes for these Robertsonian translocations are at a higher risk of producing offspring with Down syndrome.
In general, it is best to translocate monkeys at a young age, to avoid the formation of inbreeding patterns. In addition, it is important to take into account the social community of a monkey colony and the ecology of its habitat when translocating monkeys. A replicated before-and-after study conducted in temple orchards in urban Vrindaban, India found that rhesus monkeys Macaca mulatta that had been captured and transported to forest patches near their original release sites remained at the new sites over the long term. This shows that conservation-minded translocations can succeed even when there is a high level of commensalism between monkeys and humans.
Genetics
Genetics is the study of the structure and function of chromosomes. Chromosomes are long thread-like structures that contain the genetic information that determines how a person will grow and develop. Having an extra copy of chromosome 21 is what causes Down syndrome in humans. There are other genetic conditions that affect the number or shape of chromosomes. These include deletions, translocations and inversions. All of these problems can lead to physical or mental abnormalities.
A chimpanzee called Kanako has been born with trisomy 22, a genetic disorder that can cause Down syndrome in humans. She is blind and has underdeveloped teeth. She also has a congenital heart disease and stunted growth. Scientists have found that she has a lot in common with people with Down syndrome.
Chimpanzees and monkeys share 99% of their DNA with human beings. In fact, they are the closest relatives of our ancestors. However, it is very rare for a chimpanzee to have Down Syndrome. This is because chimps have 46 chromosomes while humans have 48.
It is possible for a chimpanzee to carry a full copy of the 21st chromosome, but it is not a regular occurrence. When this happens, the chimp’s mother will usually reject it and leave it to be raised by caretakers. The first chimp with trisomy 22 died in 1969, but Kanako has lived longer than anyone expected.
Although she has a genetic condition that makes her different from other chimps, Kanako is healthy and happy. She has a great personality and is easy to talk to. Her favorite things to do are swimming and playing with her friends.
While it is unlikely for a wild animal to have Down syndrome, scientists can create the condition in mice to learn more about how it works. These experiments are important because they help scientists understand how the condition affects humans. However, the same abnormalities will not happen in a pet mouse. Most cat specialists agree that Down syndrome does not exist in felines.
However, these animals may suffer from other hereditary conditions that are not caused by an extra chromosome. These disorders can affect the way that a pet eats or sleeps, or they may have a faulty heart valve. They can also have other diseases that are not related to their chromosomes, such as cancer or infections.