Cri-du-chat Syndrome


CRI-DU-CHAT SYNDROME

Cri-Du-Chat means “Cry of the cat” in French. It gets its name from its most characteristic hallmark feature in newborns were they comprise a very distinctive high-pitched, weak, mewing cat like cry during infancy caused by an abnormal development of the larynx that is usually diagnostic for the syndrome. This syndrome has many names to it as the Chromosome 5p- syndrome, Deletion 5p- syndrome, 5p minus syndrome, Cat cry syndrome, and Monosomy 5p but most commonly known as the Cri-Du-Chat Syndrome. Incidences of this disorder vary between 1 in every 20,000 - 50,000 live births worldwide and according to the 5p minus Society, approximately 50 to 60 children are born with cri du chat in the United States each year. Dr. Jerome Lejeune in 1963 described the disorder as a hereditary congenital syndrome linked to a partial deletion of the short arm, or p region in chromosome 5 but in %90 of patients the deletion is sporadic which means it could occur randomly and for it being just hereditary is just not the case.

In 10% of patients with cri du chat, there is a hereditary chromosomal rearrangement that causes the deletion. Cri-Du-Chat Syndrome occurs when a deletion of chromosomal material takes place within a particular area of the p region on chromosome 5. This deleted genetic material contains many genes which are vital for normal development and the absence of the material results in the larynx, brain, and other parts of the body to not develop as expected resulting in the features associated with cri du chat syndrome. The deletions can differ in size from extremely small and involving only band 5p15.2 to the entire short arm. Majority of the deletions arise as new mutations, approximately 12% result from unbalanced segregation of translocations or recombination involving a per centric inversion in one of the parents.

What genes and chromosomal disorders are linked to Cri-Du-Chat Syndrome? Cri-Du-Chat Syndrome is neither dominant nor recessive. The disorder is linked to Chromosome 5, where deletion of genetic materials occurs on the short or “p” arm of chromosome 5. The piece of chromosomal material deleted comprises of many vital genes necessary for proper normal development. When the missing genes are not presented the larynx, brain, and other part of the body do not develop well or as expected compared to the average newborn.

The cri-du-chat syndrome appears to be the most common human deletion disorder. Estimations of the disorder occurrence vary between in an average of 1 in every 20,000 to 50,000 live births world wide on yearly bases. According to the 5p minus Society, approximately 50 to 60 children are born with cri du chat in the United States each year. Cri-du-chat Syndrome is obtained through birth so all cases of cri du chat are newborns. The frequency in populations of profoundly retarded patients (IQ less than 20) is approximately 1%. It can occur in all races and sexes but it has been discovered that females are affected more than males. The survival rate is estimated to be anywhere from %92-94% in overall human population.

At birth, newborns comprise a very unusual distinctive high-pitched, weak, mewing cat like cry during infancy caused by an abnormal development of the larynx which is the disorders most characteristic hallmark feature that is usually diagnostic for the syndrome. As children that have the disorder get older, the cat-like cry becomes less noticeable. This can make diagnostics more difficult for older patients if the disorder was not detected at birth. Failure to thrive and mental impairment with an IQ rarely above 35 are practically always present. 85% of patients have a short stature and up to %50 of patients older than the age of 10 can communicate verbally. Cri-du-chat syndrome is characterized in young children by microcephaly (small head size), round face, hypertelorism, micrognathia, epicanthal folds, low-set ears, hypotonia which is reduced or diminished muscle tone, and severe psychomotor and mental retardation. Unusual facial features can be quite common from very subtle to very obvious features. During infancy, cri du chat patients do not gain weight or grow normally. Approximately %30 of infants with cri du chat comprises a congenital heart defect. Hypotonia also known as having poor muscle tone is also common, resulting in problems with eating and slow development. Metal retardation is present in all cases of patients with cri du chat but the degree of mental retardation varies between patients.

During infancy, diagnostics is strongly suggested if a newborn comprises a very distinctive high-pitched, weak, mewing cat like cry during infancy caused by an abnormal development of the larynx that is usually diagnostic for the syndrome. If the unusual cat-like cry is present or other features of cri du chat syndrome is suspected a chromosome test should be performed. This test is conducted by taking a blood sample form the newborn for chromosome analysis which is also called “karyotyping”, involves staining the chromosomes and examining them under a microscope . There after, some cases the deletion of material from chromosome 5 can be easily detected but in other case further testing must take place. FISH (fluorescence in-situ hybridization) is a special technique that can detect very small deletions and the majority of the deletions that cause cri du chat can be detected performing this method. Cri du chat syndrome can be detected before birth if the mother allows permission to undergo amniocentesis testing or onic villus smapling (CVS). The testing method would be recommend if either parent is known to have chromosome rearrangement, or if they have a child with cri du chat syndrome.

There is currently no treatment for the underlying disorder. Only therapies can be recommended to help stabilize and improve the disorder conditions. Treatments consist of supportive and developmental therapy. Medical problems can be improved by the following: Physiotherapy, Speech therapy, Occupational therapy, and behavioral management if necessary. Even after so many previous studies with cri du chat throughout the years, we still have yet to fulfill a treatment or prevention medications.

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