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Cri-Du-Chat Syndrome: Symptoms and Causes

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Cri-Du-Chat Syndrome

Introduction

Cri-du-chat is an autosomal syndrome that is caused by a large or small deletion from a portion of the short arm of chromosome. This syndrome is also known as the 5p deletion syndrome where the P describes the short hand chromosome and Lejeune's syndrome. It is also called cat cry syndrome which is a French translation of Cri-du-chat, because of its similarity to the high pitched cat cry like sound a new born child makes. This sound is supposed to disappear a few weeks after birth and may or may not persists in to adulthood.

In 1958 Dr. Jerome Lejeune discovered down syndrome. He discovered that the chromosomal link to down syndrome. This discovery was ground breaking for discoveries in genetics because it was the first time that an intellectual disability and a chromosomal defect were linked together and this earned him multiple prestigious awards. Up on continuing his research on chromosomal liked disorders, he also discovered that down syndrome was caused by an extra chromosome on pare 21 and he also noticed a deletion on the 5th chromosome which is the cause for Cri-du-chat syndrome. (1)

Symptoms and OMIM Number

Cri- du- chat

The relationship of chromosomal alteration and genetic disease was observed that the main clinical feature was the high pitched cry and hindered mental capacity (Mainardi, 2006). The OMIM number for this syndrome is # 123450. The number sign is used to indicate that it is a well described partial aneusomy. Syndrome causes many phenotypical changes which depend on the size of the deletion. Some or all of the symptoms might be present in a patient. It has also been found that the deletion of the telomerase reverse transcriptase gene (TERT; 187270) well as evidence that deletion of the telomerase reverse transcriptase gene (TERT; 187270) is present which is also responsible for some of the phenotypical changes. (2) Besides the high pitched cry, Cri-du-chat is characterized by failure to thrive, broad nasal bridge, round moon shaped face with hypertelorism, Anisocoria, undersized jaw and heads , depleted motor senses hypertonia, small carpals, low birth weight and incomplete intestinal rotation in infants.

There are some less distinctive symptoms such as separation of rectus and abdomen, cardiac abnormalities including atrial and ventricular septum defects, primary immunodeficiency, an epicanthal fold which covers the inner corned of the eye and inguinal hernia. ("Chromosome 5," 2017).)

Once the infant is born there is a low mortality rate until adulthood where most of the symptoms observed as a child continue on with addition of misalignment of teeth, skeletal problems, eye defects and in some cases neurological malformation, Syndactyly, undescended testis in male patients, and skin tags on the ear occur. (Mainardi, 2006,)

Clinical causes of symptoms

The syndrome is caused by a deletion of the short arm, which is also denoted by P, of chromosome 5. Chromosome 5 contains more than 900 genes that code for specific proteins such as interleukins, protocadherins and complement proteins. The function of these proteins range from regulation of immune system, nervous system controls and muscle formation and strength. The deletion of Some Sections of chromosome 5 such as 5p15.3, specifically at markers D5S731 and D5S760, are directly associated with the cat like cry and speech delay. Another region called 5p15.2, specifically CTNND2, is related to lower intellectual ability, and dysmorphism of head size and facial features. The severity of mental and motor capacities can depend up on the size of the chromosomal deletion ("Chromosome 5," 2017). Although the affected family members apparently shared deletions of the same size, the variation in mental symptoms within this family suggested that other factors besides the size and location of 5p deletions may modify the mental presentation of patients with cri-du-chat syndromeThey suggested that a cranial developmental field, originating from the notochordal location, is involved in the manifestations of cri-du-chat syndromehowever, the characteristic cat-like cry without the typical dysmorphic and severe developmental features of the syndrome has been found in individuals with a deletion confined to 5p15.3The cranial base angle was in most cases reduced and in no cases increased compared to age-related standards for normal individuals. Malformations in the bony contours of the sella turcica and the clivus occurred in cri-du-chat patients with terminal deletions.

Frequency

The frequency of the disease is 1:15000 to 1: 50000 of new born infants. Cri-du-chat makes up 1% of profoundly retarded patients who have IQ levels that are less than 30. Since it is a genetic deletion it doesn't have a preference as far as race nut it has a slight female dominance ratio of 4:3. This syndrome doesn't have a latency, the symptoms are present starting from birth and continue to show the symptoms in to adulthood. In most cases it has been seen that the symptoms become more severe in to adulthood. (Harvard et al., 2005, pp. 341-51).

Inheritance pattern

Cru de chat is not an inherited syndrome. It is a random deletion that occurs during meiosis and can occur without the parents being affected. However close to 10% of the affected individuals can inherit a chromosomal abnormality from unaffected parents. This abnormality is caused by chromosomal rearrangement called Balanced Translocation where the genetic material is still intact and doesn't cause any health problems. However when this trait is passed down from one or two parents it has a high chance of becoming and Unbalanced Translocation which can cause a genetic material to be added or deleted. In the case of cri du chat the short arm of chromosome 5 experiences a large or a small portion deletion which causes the syndrome.

In some cases the catlike cry can be present without the physical abnormalities. This is more evident in the deletion at a specific location in the chromosome 5p15.3. Malformation in the cranial base was reduced and compared to a standard individual it doesn't show a major difference. However malformations in the contours the skull such as in Sella Turcica occur in patients that have terminal deletions. In one of the studies conducted with in the same family showed different symptoms and levels of mental retardation even though they shared the same size deletion. This suggests that not only the size but the location of deletion affects the severity of the syndrome (2)

References

Cerruti Mainardi, P. (2006). Cri du Chat syndrome. Orphanet Journal of Rare Diseases, 1, 33. http://doi.org/10.1186/1750-1172-1-33

Chromosome 5. (2017, January 24). Retrieved January 29, 2017, from U.S National Library of Medicine. U.S department of health & human services website: https://ghr.nlm.nih.gov/chromosome/5

Chromosome 5. (2017, January 24). Retrieved January 29, 2017, from U.S National Library of Medicine. U.S department of health & human services website: https://ghr.nlm.nih.gov/condition/cri-du-chat-syndrome#genes

Harvard, C., Malenfant, P., Koochek, M., Creighton, S., Mickelson, E., Holden, J. Rajcan-Separovic, E. (2005). A variant Cri du Chat phenotype and autism spectrum disorder in a subject with de novo cryptic microdeletions involving 5p15.2 and 3p24.3-25 detected using whole genomic array CGH. Clinical Genetics, 67(4). http://dx.doi.org/10.1111/ j.1399-0004.2005.00406.x

https://lejeuneusa.org/genetic-intellectual-disabilities/cri-du-chat-syndrome#.WJpP-n_Rs8c (1)

http://www.omim.org/entry/123450?search=cri%20du%20chat&highlight=du%20cri%20chat (2)


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