Cat Eye Syndrome
1. When does the chromosomal defect occur?
Cat eye syndrome is a rare chromosomal disorder that develops during the growth of the foetus in the womb. It may be diagnosed before birth but can be confirmed once the baby is born.
2. What is the chromosomal change or abnormality
The chromosomal abnormality in cat eye syndrome is in the 22nd chromosome. Individuals with normal chromosomal makeup have two 22nd chromosomes which has a short arm (called “22p”) and a long arm (called “22q”). In individuals with cat eye syndrome, a part of the short arm, and some of the long arm are present three or four times instead of twice in the cells of the body. This is known as trisomy and tetrasomy. (Rare Diseases, 2015)
Cat eye syndrome is a rare chromosomal disorder that develops during the growth of the foetus in the womb. It may be diagnosed before birth but can be confirmed once the baby is born.
2. What is the chromosomal change or abnormality
The chromosomal abnormality in cat eye syndrome is in the 22nd chromosome. Individuals with normal chromosomal makeup have two 22nd chromosomes which has a short arm (called “22p”) and a long arm (called “22q”). In individuals with cat eye syndrome, a part of the short arm, and some of the long arm are present three or four times instead of twice in the cells of the body. This is known as trisomy and tetrasomy. (Rare Diseases, 2015)
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3. How does the chromosomal abnormality happen?
Cat eye syndrome occurs when there is trisomy or tetrasomy of chromosome 22. This means that the chromosome is copied 3 or 4 times instead of the usual 2 times. It usually arises spontaneously even if the parents don't have the syndrome. However, parents with the syndrome have a higher chance of passing on the abnormality. There are many ways it can occur. One way is that there was an error in the parent's reproductive cell. Other times, it could be a result of "balanced translocation" in one of the parents. Balanced translocation is when certain parts of chromosomes break off and are rearranged into different chromosomes. This ends up changing the genetic material and an altered set of chromosomes.
Cat eye syndrome occurs when there is trisomy or tetrasomy of chromosome 22. This means that the chromosome is copied 3 or 4 times instead of the usual 2 times. It usually arises spontaneously even if the parents don't have the syndrome. However, parents with the syndrome have a higher chance of passing on the abnormality. There are many ways it can occur. One way is that there was an error in the parent's reproductive cell. Other times, it could be a result of "balanced translocation" in one of the parents. Balanced translocation is when certain parts of chromosomes break off and are rearranged into different chromosomes. This ends up changing the genetic material and an altered set of chromosomes.
4. Is the chromosomal abnormality gender related?
Cat eye syndrome affects both genders equally. Furthermore, no race or ethnic group has been shown to be more affected than other races.
5. What causes the chromosomal abnormality
The exact cause of the syndrome is not fully understood. In many cases, the syndrome appears spontaneously because of an error in the division of a parent's reproductive cell. In these cases, the parents have normal chromosomes and cat eye syndrome develops in the child spontaneously without inheriting it from the parent. If it is not inherited from the parent, the parents don't have to worry about another child developing the syndrome. Other times, it is inherited from the parent. In these cases, parents have the marker chromosome and sometimes show mild symptoms of the syndrome. A marker chromosome is a structurally abnormal chromosome and sometimes have little effect on the person or is made out of inactive genetic material. In cases which it is inherited, the parents themselves often do not realise they have cat eye syndrome until they give birth to a child with malformations. (http://cateyesyndrome.info/what-is-cat-eye-syndrome/frequently-asked-questions/, 2015)
6. How is the chromosomal abnormality diagnosed?
Sometimes, diagnosis of cat eye syndrome can be suspected before birth through specialised tests such as ultrasounds, amniocentesis, and/or chorionic villus sampling (CVS) (Rare Diseases, 2015). Other times, cat eye syndrome is confirmed after birth through more tests such as specialised tests to identify DNA sequences. Other tests can also be performed to detect certain abnormalities associated with cat eye syndrome including an eye examination and a hearing examination. (Rare Diseases, 2015).
7. How common is the chromosomal abnormality?
Since it is extremely rare, and oftentimes people do not get officially diagnosed with cat eye syndrome, scientists are only able to make a rough estimation of the amount of people with the disease. It is estimated that cat eye syndrome affects 1 in 74,000 people worldwide.
Cat eye syndrome affects both genders equally. Furthermore, no race or ethnic group has been shown to be more affected than other races.
5. What causes the chromosomal abnormality
The exact cause of the syndrome is not fully understood. In many cases, the syndrome appears spontaneously because of an error in the division of a parent's reproductive cell. In these cases, the parents have normal chromosomes and cat eye syndrome develops in the child spontaneously without inheriting it from the parent. If it is not inherited from the parent, the parents don't have to worry about another child developing the syndrome. Other times, it is inherited from the parent. In these cases, parents have the marker chromosome and sometimes show mild symptoms of the syndrome. A marker chromosome is a structurally abnormal chromosome and sometimes have little effect on the person or is made out of inactive genetic material. In cases which it is inherited, the parents themselves often do not realise they have cat eye syndrome until they give birth to a child with malformations. (http://cateyesyndrome.info/what-is-cat-eye-syndrome/frequently-asked-questions/, 2015)
6. How is the chromosomal abnormality diagnosed?
Sometimes, diagnosis of cat eye syndrome can be suspected before birth through specialised tests such as ultrasounds, amniocentesis, and/or chorionic villus sampling (CVS) (Rare Diseases, 2015). Other times, cat eye syndrome is confirmed after birth through more tests such as specialised tests to identify DNA sequences. Other tests can also be performed to detect certain abnormalities associated with cat eye syndrome including an eye examination and a hearing examination. (Rare Diseases, 2015).
7. How common is the chromosomal abnormality?
Since it is extremely rare, and oftentimes people do not get officially diagnosed with cat eye syndrome, scientists are only able to make a rough estimation of the amount of people with the disease. It is estimated that cat eye syndrome affects 1 in 74,000 people worldwide.
8. How are the chromosomes different compared to normal chromosomes? (Include a karyotype)
People with cat eye syndrome have 3 or 4 copies of chromosome 22. In normal people, there are only 2 copies of the chromosome. Every other chromosome is the same as it would be on a normal person.
People with cat eye syndrome have 3 or 4 copies of chromosome 22. In normal people, there are only 2 copies of the chromosome. Every other chromosome is the same as it would be on a normal person.
9. How does the chromosomes abnormality affect health, development and lifespan? (Include symptoms)
Life with cat eye syndrome is different for every individual and may come with several or no health complications. In fact, some people show no signs of cat eye syndrome and need genetic testing to confirm they have it. Furthermore, intelligence is not usually affected but if it is then it is usually only mild, not severe impairment. Most importantly, it does not have a great effect on a person's lifespan. Unless, the person presents severe symptoms, especially heart complications, a person with cat eye syndrome is usually able to live out a full life. Some of the most common visible symptoms of cat eye syndrome are abnormally shaped ears, flat noses and small chins, fused nasal passages (choanal atresia), anal atresia and cleft palate.
10. Is the disease treatable/how?
For the most part, it isn't the disease that needs to be treated, but rather the symptoms and bodily malfunctions that come with it. Treatment of cat eye syndrome requires the collaboration of a team of specialised medical professionals which includes paediatricians, surgeons, cardiologists, eye specialists, hearing specialists, orthopedists, physicians specialising in abnormalities of the digestive tract and other health care professionals. Furthermore, each case is unique and requires tailored treatments. This is because the severity of the condition depends in each person. One person might have no eyesight problems or hearing problems but might have heart problems. Another person might be completely deaf in both ears but have no other health problems. And another person might only be deaf in one ear. Because of this, a team of medical professionals need to work together to decide the best treatment for the individual.
Life with cat eye syndrome is different for every individual and may come with several or no health complications. In fact, some people show no signs of cat eye syndrome and need genetic testing to confirm they have it. Furthermore, intelligence is not usually affected but if it is then it is usually only mild, not severe impairment. Most importantly, it does not have a great effect on a person's lifespan. Unless, the person presents severe symptoms, especially heart complications, a person with cat eye syndrome is usually able to live out a full life. Some of the most common visible symptoms of cat eye syndrome are abnormally shaped ears, flat noses and small chins, fused nasal passages (choanal atresia), anal atresia and cleft palate.
10. Is the disease treatable/how?
For the most part, it isn't the disease that needs to be treated, but rather the symptoms and bodily malfunctions that come with it. Treatment of cat eye syndrome requires the collaboration of a team of specialised medical professionals which includes paediatricians, surgeons, cardiologists, eye specialists, hearing specialists, orthopedists, physicians specialising in abnormalities of the digestive tract and other health care professionals. Furthermore, each case is unique and requires tailored treatments. This is because the severity of the condition depends in each person. One person might have no eyesight problems or hearing problems but might have heart problems. Another person might be completely deaf in both ears but have no other health problems. And another person might only be deaf in one ear. Because of this, a team of medical professionals need to work together to decide the best treatment for the individual.
Fun Facts!!!
1. Cat eye syndrome is also known as: CES, Schmid-Fraccaro Syndrome, Tetrasomy and Partial Trisomy.
2. John Ritter, Henry Cavill and Arnaud Clement are famous people with this syndrome.
3. Despite being known as "Cat eye syndrome", less than half of the affected have cat-like eyes.
4. People with cat eye syndrome are able to reproduce normally.
5. Some people show no signs of the syndrome and need genetic testing to confirm it.
6. Most of the time, only one person in a family will have cat eye syndrome.
2. John Ritter, Henry Cavill and Arnaud Clement are famous people with this syndrome.
3. Despite being known as "Cat eye syndrome", less than half of the affected have cat-like eyes.
4. People with cat eye syndrome are able to reproduce normally.
5. Some people show no signs of the syndrome and need genetic testing to confirm it.
6. Most of the time, only one person in a family will have cat eye syndrome.