Essay On Cri Du Chat Syndrome
Introduction
Cri du Chat Syndrome is named after its very unique symptom: a cat-like cry. However, this disorder has other names as well, such as, Cat-Cry Syndrome, Chromosome 5p Syndrome, 5p Deletion Syndrome, Monosomy 5p Syndrome, 5p-Syndrome, LeJeune’s Syndrome, and many more (Kelly, 2013). As appropriately named, it is a rare genetic disorder caused by a partial deletion of chromosome 5p, where the p represents the short arm of chromosome 5. This is caused by the breakage during the making of gametes in males (National Organization for Rare Disorders (NORD), 2016). As a result, Cri du Chat patients show many symptoms, but they are not always the same for all patients, as some can lack a lot of the chromosome, while others lack a little of it. The …show more content…
most common symptoms shown are: the cat cry, a small jaw, weak muscles, and slow brain development (Blatnik et al., 2014). Unfortunately, since it is a genetic disorder, Cri du Chat patients cannot do much about it, as it cannot be controlled.
In 1963, the discovery of Cri du Chat was made by a French geneticist, Jérôme-Jean-Louis-Marie LeJeune, and his colleagues. They identify the chromosome 5p deletions and appropriately name the genetic disorder after the cat-like cries made by many patients; Cri du Chat, or cat’s cry (Encyclopedia Britannica, 2016). However, it was later found that not all Cri du Chat patients have this cry, but still show all of the other symptoms (Alexeyev et al., 2015). Aside from the mewing cry, the symptom of slow brain development is extremely common. Almost all Cri du Chat patients have below-average brain functions and lack general knowledge and intellect. In fact, 1% of the mentally challenged are people with Cri du Chat (Kelly, 2013).
As Cri du Chat is a rare genetic disorder, only 1/15 000 to 1/50 000 live births, slightly more females, are diagnosed with it every year. The usual case of Cri du Chat is from the partial deletion of chromosome 5, which makes up 80-90% of Cri du Chat cases (Dangare et al., 2012). However, this is not the only way, as some extremely rare cases, are caused by an unbalanced translocation inherited from their parents. This makes up 10-15% of Cri du Chat cases (Alexeyev et al., 2015). Although the majority of Cri du Chat patients show the same complications as a child and as an adult, they have the same life expectancy as any other person. They still cannot live alone, but with the help of language and physical therapy, and education, adult patients improve their lifestyles (Encyclopedia Britannica, 2016).
Etiology
Cri du Chat is a chromosomal disorder caused by abnormal chromosome structure.
As learned in class During the formation of gametes, there is a breakage of chromosome 5, which is a partial deletion. In meiosis 1, the crossing over, or swapping of segments of chromosomes, does not happen successfully. The fragment of chromosome 5, fails to reattach to its homolog as it is lost, which is what develops as Cri du Chat Syndrome. Furthermore, the specific region that is not present in Cri du Chat patients, are regions around 5p15.2 – 5p15.3, where the p represents the short arm of chromosome 5, and the numbers specify the area on it (NORD, 2016). Although this may seem like a very small area, three significant genes are within it. They are SEMAF, CTNND2, and TERT, which are short for, semaphorin F, delta-catenin, and telomerase reverse transcriptase, respectively (Kelly, 2013). Tests reveal that patients with more of the SEMAF and CTNND2 genes have a better IQ than patients with less of it. Therefore, these genes are vital for brain development. Finally, TERT is said to be related to physical features (Santo et al., 2016). Overall, these three genes are important for living, which is why patients cannot live on their
own. The most researched feature of Cri du Chat is absolutely the cat-like cry, which is in the region of 5p15.31 (Blatnik et al., 2014). However, the cat-like cry goes away at around the age of 2 (National Human Genome Research Institute (NHGRI), 2013). Additionally, the next most common symptom aside from the cat-like cry is slow brain development. The stunt in brain development leads to hyperactivity, slow understanding, and communication problems (Alexeyev et al., 2015). Other symptoms include dysmorphism, which is a difference in physical appearance and body structures, such as down-slanted eyes and low-set ears. Microcephaly, micrognathia and hypertelorism are also examples of dysmorphism, and are defined as a small head, a small jaw, and increased space between two body parts, particularly the eyes, respectively (Dangare et al., 2012). Furthermore, hearing problems and sensitivity to loud sounds can be seen in patients, as well (National Institutes of Health (NIH), 2016). Although there are many more symptoms shown by patients, these are the most common among all of them.
All symptoms of Cri du Chat will not always be present in all patients, as the size of the deletion of chromosome 5, can vary. Thus, the more that is lacked, the more symptoms are shown (Santo et al., 2016). For example, although Cri du Chat is known for a cat-like cry, not all patients have it. The source of the cry, as well as of speech delay is from the region 5p15.31, which is linked to the thoracic tissue and the larynx (Blatnik et al., 2014). Moreover, the symptoms of facial dysmorphism are linked to the specific regions of 5p15.24 – 5p15.26 (Alexeyev et al., 2015). The symptom of hyperactivity and learning disabilities, which is shown in 80-90% of patients, is caused by the underdevelopment of brain stems, brain tissues, and brain cells, from the lack of SEMAF and CTNND2 (Cho et al., 2013). In addition, 8.4% of patients have impaired hearing because of the blockage of the eardrum due to their abnormal facial structures (NIH, 2016). Therefore, the small partial deletion of chromosome 5, surely lead to many symptoms and impacts the life of many.
A partial deletion of chromosome 5 is the main way of getting Cri du Chat, but there are many other ways. 10-15% of Cri du Chat patients inherit Cri du Chat through unbalanced translocation (Alexeyev et al., 2015). A translocation can occur during meiosis 1, when the crossing over or swapping of segments of chromosomes, does not successfully reattach. Instead of getting lost in deletion, the segments that are attaching, attach to a non-homologous homolog. An unbalanced translocation is caused when a parent carries a balanced translocation and passes it on to their child, making it unbalanced (EuroGentest, 2011). The chances of an unbalanced translocation to happen are very low, but it does happen. It is also reported that there are recurrences of getting another baby with Cri du Chat. This is related to the way of unbalanced translocations, as the parent still carries the balanced translocation. However, the chances are very low: 8.7-18.8% (Dangare et al., 2012). Finally, interstitial deletions, where there are two breaks instead of one in the chromosome (3% - 5%), mosaicism (Encyclopedia Britannica, 2016), where there are two or more different genotypes in a single egg (1.4%), inversions, where a segment is attached in reverse order during crossing over (0.5%), ring chromosomes, where the ends of the chromosome are joined together (0.5%), are very rare cases that have been reported to have led to Cri du Chat as well, but not much information is known about them (Alexeyev et al., 2015). To conclude, Cri du Chat is generally a very rare genetic disorder, so these ways of getting it, is extremely uncommon.
This genetic disorder affects many essential organs, such as the brain, along with the nervous system, the larynx, the heart, the lungs, and most muscles,. Cri du Chat patients lack SEMAF and CTNND2, which lead to stunted brain development and overall, a dysfunctional nervous system. Specifically, the pons and the cerebellum, which are major parts of the brain that are linked to the spinal cord and brainstems, are strongly affected (Blatnik et al., 2014). Furthermore, the larynx and thoracic tissue are affected, leading to the cat-like cry and speech delay. The hearts and lungs of Cri du Chat patients can sometimes be affected as well, as their body structure and undeveloped brain structure, cause heart defects and breathing problems (Kelly, 2013). Lastly, hypotonia, also known as increased flexibility of muscles, is exchanged with hypertonia, which is the inability to stretch muscles, as patients get older (Blatnik et al., 2014). Unfortunately, with all these organs affected in patients with Cri du Chat, they cannot live on their own (Encyclopedia Britannica, 2016). Adults with Cri du Chat need assistance with their everyday routine, as they are mentally only five or six years old (Dangare et al., 2012). Overall, many organs are affected by this disorder and patients live with most of these health concerns, throughout their lives.
Conclusion
Cri du Chat Syndrome is an uncommon genetic disorder that impacts patients’ lives immensely. There are multiple symptoms that are shown by patients, such as the unique cat-like cry, that goes away at around the age of 2, dysmorphism, and the underdevelopment of the brain. The cat-like cry is what gives this disorder its name, and it is what makes it easily to distinguish from other genetic disorders. Next, dysmorphism or abnormal body structure, leads to many negative effects of the patients’ organs, such as the brain, heart and lungs. Then, the stunted brain development makes it harder for patients’ to communicate and learn everyday skills that are essential for living, resulting in the inability to live on their own. Unfortunately, these are only a few of the symptoms shown by Cri du Chat patients. The large number of symptoms shown by Cri du Chat patients is due to the lack of crucial genes in chromosome 5. The partial deletion of this chromosome eliminates SEMAF, CTNND2, and TERT, which are short for, semaphorin F, delta-catenin, telomerase reverse transcriptase, respectively. It is proven that SEMAF and CTNND2 are responsible for the intellect and understanding of patients, as patients that have less of each, have lower IQ levels. Furthermore, the lack of the TERT gene is said to lead to abnormal physical features and body structure. Although Cri du Chat Syndrome is mainly caused by the partial deletion of chromosome 5, specifically the regions of 5p15.2 – 5p15.3, it has many harmful impacts on patients. In conclusion, the three main genes that are absent in Cri du Chat patients, are vital for living and being an independent individual.
Cri du Chat Syndrome is named after its very unique symptom: a cat-like cry. However, this disorder has other names as well, such as, Cat-Cry Syndrome, Chromosome 5p Syndrome, 5p Deletion Syndrome, Monosomy 5p Syndrome, 5p-Syndrome, LeJeune’s Syndrome, and many more (Kelly, 2013). As appropriately named, it is a rare genetic disorder caused by a partial deletion of chromosome 5p, where the p represents the short arm of chromosome 5. This is caused by the breakage during the making of gametes in males (National Organization for Rare Disorders (NORD), 2016). As a result, Cri du Chat patients show many symptoms, but they are not always the same for all patients, as some can lack a lot of the chromosome, while others lack a little of it. The …show more content…
most common symptoms shown are: the cat cry, a small jaw, weak muscles, and slow brain development (Blatnik et al., 2014). Unfortunately, since it is a genetic disorder, Cri du Chat patients cannot do much about it, as it cannot be controlled.
In 1963, the discovery of Cri du Chat was made by a French geneticist, Jérôme-Jean-Louis-Marie LeJeune, and his colleagues. They identify the chromosome 5p deletions and appropriately name the genetic disorder after the cat-like cries made by many patients; Cri du Chat, or cat’s cry (Encyclopedia Britannica, 2016). However, it was later found that not all Cri du Chat patients have this cry, but still show all of the other symptoms (Alexeyev et al., 2015). Aside from the mewing cry, the symptom of slow brain development is extremely common. Almost all Cri du Chat patients have below-average brain functions and lack general knowledge and intellect. In fact, 1% of the mentally challenged are people with Cri du Chat (Kelly, 2013).
As Cri du Chat is a rare genetic disorder, only 1/15 000 to 1/50 000 live births, slightly more females, are diagnosed with it every year. The usual case of Cri du Chat is from the partial deletion of chromosome 5, which makes up 80-90% of Cri du Chat cases (Dangare et al., 2012). However, this is not the only way, as some extremely rare cases, are caused by an unbalanced translocation inherited from their parents. This makes up 10-15% of Cri du Chat cases (Alexeyev et al., 2015). Although the majority of Cri du Chat patients show the same complications as a child and as an adult, they have the same life expectancy as any other person. They still cannot live alone, but with the help of language and physical therapy, and education, adult patients improve their lifestyles (Encyclopedia Britannica, 2016).
Etiology
Cri du Chat is a chromosomal disorder caused by abnormal chromosome structure.
As learned in class During the formation of gametes, there is a breakage of chromosome 5, which is a partial deletion. In meiosis 1, the crossing over, or swapping of segments of chromosomes, does not happen successfully. The fragment of chromosome 5, fails to reattach to its homolog as it is lost, which is what develops as Cri du Chat Syndrome. Furthermore, the specific region that is not present in Cri du Chat patients, are regions around 5p15.2 – 5p15.3, where the p represents the short arm of chromosome 5, and the numbers specify the area on it (NORD, 2016). Although this may seem like a very small area, three significant genes are within it. They are SEMAF, CTNND2, and TERT, which are short for, semaphorin F, delta-catenin, and telomerase reverse transcriptase, respectively (Kelly, 2013). Tests reveal that patients with more of the SEMAF and CTNND2 genes have a better IQ than patients with less of it. Therefore, these genes are vital for brain development. Finally, TERT is said to be related to physical features (Santo et al., 2016). Overall, these three genes are important for living, which is why patients cannot live on their
own. The most researched feature of Cri du Chat is absolutely the cat-like cry, which is in the region of 5p15.31 (Blatnik et al., 2014). However, the cat-like cry goes away at around the age of 2 (National Human Genome Research Institute (NHGRI), 2013). Additionally, the next most common symptom aside from the cat-like cry is slow brain development. The stunt in brain development leads to hyperactivity, slow understanding, and communication problems (Alexeyev et al., 2015). Other symptoms include dysmorphism, which is a difference in physical appearance and body structures, such as down-slanted eyes and low-set ears. Microcephaly, micrognathia and hypertelorism are also examples of dysmorphism, and are defined as a small head, a small jaw, and increased space between two body parts, particularly the eyes, respectively (Dangare et al., 2012). Furthermore, hearing problems and sensitivity to loud sounds can be seen in patients, as well (National Institutes of Health (NIH), 2016). Although there are many more symptoms shown by patients, these are the most common among all of them.
All symptoms of Cri du Chat will not always be present in all patients, as the size of the deletion of chromosome 5, can vary. Thus, the more that is lacked, the more symptoms are shown (Santo et al., 2016). For example, although Cri du Chat is known for a cat-like cry, not all patients have it. The source of the cry, as well as of speech delay is from the region 5p15.31, which is linked to the thoracic tissue and the larynx (Blatnik et al., 2014). Moreover, the symptoms of facial dysmorphism are linked to the specific regions of 5p15.24 – 5p15.26 (Alexeyev et al., 2015). The symptom of hyperactivity and learning disabilities, which is shown in 80-90% of patients, is caused by the underdevelopment of brain stems, brain tissues, and brain cells, from the lack of SEMAF and CTNND2 (Cho et al., 2013). In addition, 8.4% of patients have impaired hearing because of the blockage of the eardrum due to their abnormal facial structures (NIH, 2016). Therefore, the small partial deletion of chromosome 5, surely lead to many symptoms and impacts the life of many.
A partial deletion of chromosome 5 is the main way of getting Cri du Chat, but there are many other ways. 10-15% of Cri du Chat patients inherit Cri du Chat through unbalanced translocation (Alexeyev et al., 2015). A translocation can occur during meiosis 1, when the crossing over or swapping of segments of chromosomes, does not successfully reattach. Instead of getting lost in deletion, the segments that are attaching, attach to a non-homologous homolog. An unbalanced translocation is caused when a parent carries a balanced translocation and passes it on to their child, making it unbalanced (EuroGentest, 2011). The chances of an unbalanced translocation to happen are very low, but it does happen. It is also reported that there are recurrences of getting another baby with Cri du Chat. This is related to the way of unbalanced translocations, as the parent still carries the balanced translocation. However, the chances are very low: 8.7-18.8% (Dangare et al., 2012). Finally, interstitial deletions, where there are two breaks instead of one in the chromosome (3% - 5%), mosaicism (Encyclopedia Britannica, 2016), where there are two or more different genotypes in a single egg (1.4%), inversions, where a segment is attached in reverse order during crossing over (0.5%), ring chromosomes, where the ends of the chromosome are joined together (0.5%), are very rare cases that have been reported to have led to Cri du Chat as well, but not much information is known about them (Alexeyev et al., 2015). To conclude, Cri du Chat is generally a very rare genetic disorder, so these ways of getting it, is extremely uncommon.
This genetic disorder affects many essential organs, such as the brain, along with the nervous system, the larynx, the heart, the lungs, and most muscles,. Cri du Chat patients lack SEMAF and CTNND2, which lead to stunted brain development and overall, a dysfunctional nervous system. Specifically, the pons and the cerebellum, which are major parts of the brain that are linked to the spinal cord and brainstems, are strongly affected (Blatnik et al., 2014). Furthermore, the larynx and thoracic tissue are affected, leading to the cat-like cry and speech delay. The hearts and lungs of Cri du Chat patients can sometimes be affected as well, as their body structure and undeveloped brain structure, cause heart defects and breathing problems (Kelly, 2013). Lastly, hypotonia, also known as increased flexibility of muscles, is exchanged with hypertonia, which is the inability to stretch muscles, as patients get older (Blatnik et al., 2014). Unfortunately, with all these organs affected in patients with Cri du Chat, they cannot live on their own (Encyclopedia Britannica, 2016). Adults with Cri du Chat need assistance with their everyday routine, as they are mentally only five or six years old (Dangare et al., 2012). Overall, many organs are affected by this disorder and patients live with most of these health concerns, throughout their lives.
Conclusion
Cri du Chat Syndrome is an uncommon genetic disorder that impacts patients’ lives immensely. There are multiple symptoms that are shown by patients, such as the unique cat-like cry, that goes away at around the age of 2, dysmorphism, and the underdevelopment of the brain. The cat-like cry is what gives this disorder its name, and it is what makes it easily to distinguish from other genetic disorders. Next, dysmorphism or abnormal body structure, leads to many negative effects of the patients’ organs, such as the brain, heart and lungs. Then, the stunted brain development makes it harder for patients’ to communicate and learn everyday skills that are essential for living, resulting in the inability to live on their own. Unfortunately, these are only a few of the symptoms shown by Cri du Chat patients. The large number of symptoms shown by Cri du Chat patients is due to the lack of crucial genes in chromosome 5. The partial deletion of this chromosome eliminates SEMAF, CTNND2, and TERT, which are short for, semaphorin F, delta-catenin, telomerase reverse transcriptase, respectively. It is proven that SEMAF and CTNND2 are responsible for the intellect and understanding of patients, as patients that have less of each, have lower IQ levels. Furthermore, the lack of the TERT gene is said to lead to abnormal physical features and body structure. Although Cri du Chat Syndrome is mainly caused by the partial deletion of chromosome 5, specifically the regions of 5p15.2 – 5p15.3, it has many harmful impacts on patients. In conclusion, the three main genes that are absent in Cri du Chat patients, are vital for living and being an independent individual.