Is Cri Du Chat Syndrome Inherited?
•Most cases of cri du chat syndrome are not inherited.
• The chromosomal deletion usually occurs as a random event during the formation of reproductive cells (eggs or sperm) or in early fetal development.
•People with cri du chat typically have no history of the condition in their family.
•About 10 percent of people with cri du chat syndrome inherit the chromosome with a deleted segment from an unaffected parent. In these cases, the parent carries a chromosomal rearrangement called a balanced translocation, in which no genetic material is gained or lost.
Treatment :
•Gene therapy is in its infancy and no techniques have yet been developed to treat these types of large chromosomal abnormalities.
•however there is therapy to help the child achieve his or her developmental potential.
•Early intervention programs, using a variety of therapies and educational strategies, focus on enhancing physical, intellectual, sensory and social development and have been shown to greatly improve the future outlook for the child.
•Early Intervention programs should include:
•Physiotherapy
•Speech Therapy
•Occupational Therapy
•Behavioural management (if necessary)
•Since most children with the syndrome experience severe speech development problems, speech and language therapy are vital.
•The early introduction of alternative means of communication, including a sign language such as Makaton along with a pictorial symbol system, will enhance the child's speech development, language acquisition and behaviour.
•Children with cri du chat syndrome are usually keen to communicate and many will develop their own signs and gestures to get what they want often prefering these to the more difficult formal signs.
•Children who cannot communicate effectively experience a great deal of frustration and behviour problems can develop as a result.
•Improving a child's ability to communicate by any means not only helps them to make their needs known,
• but also helps them to develop intellectually and socially, improving the quality of their lives immeasurably.
Recent Research:
•Research in the past has been concentrated in the area of medical genetics with very limited investigation of the developmental and behavioural aspects of the syndrome.
•The gene locations for the cry and the other features were found to be on separate bands of the chromosome
•Developmental researchers have been collaborating with genetic researchers for a number of years in an attempt to define how the varying genetic combinations (genotype) occurring in this syndrome affect the development and features a particular individual displays (phenotype).
•This collaboration assists the geneticist to track down the location of particular genes and identify their activity. In the future it is hoped that it will help developmental specialists to predict how severely a particular child's development will be affected. This is not possible with our current level of knowledge.
Treatment of the syndrome
Characteristics of the Syndrome
•Major identifying characteristics•Monotone, weak, cat-like cry
•Small head (microcephally)
•High palate
•Round face
•Small receding chin (micrognathia)
•Widely spaced eyes (hypertelorism)
•Low set ears
•Low broad nasal ridge
•Folds of skin over the upper eyelid (epicanthic folds)
•Distinctive palmar creases (creases on the palms of the hands)
•feeding problems because of difficulty swallowing and sucking,
•low birth weight and poor growth
•The most distinctive characteristic,cat-like cry.
• The cry is caused by abnormal larynx development, which becomes normal within a few weeks of birth
•Infants with cri du chat have low birth weight and may have respiratory problems.
•Some people with this disorder have a shortened lifespan, but most have a normal life expectancy
•Not every child will have every feature. Those only mildly affected may have very few or they may be less obvious.
•Babies with cri-du-chat are usually small at birth, and may have respiratory problems.
•Often, the larynx doesn't develop correctly, which causes the signature cat-like cry.
• They may have a small head (microcephaly), an unusually round face, a small chin, widely set eyes, folds of skin over their eyes, and a small bridge of the nose.
•Several problems occur inside the body, as well. A small number of children have heart defects, muscular or skeletal problems, hearing or sight problems, or poor muscle tone.
• As they grow, people with cri-du-chat usually have difficulty walking and talking correctly.
•They may have behavior problems (such as hyperactivity or aggression), and severe mental retardation. Unfortunately, most people with this disorder don't survive to adulthood.
•Intellectual disability ranging from mild to profound with the majority being moderate to severe
•Speech and language impairment varying from mild to profound.
• A small number do not speak at all but all can communicate with one or a combination of methods. .
•Low muscle tone and delayed motor development.
•Short attention span (almost 100%).
•Hyperactivity (approximately 25%)
•Challenging behaviours including obsessive, repetitive and sometimes self-harming behaviours such as head-banging and hitting, biting or scratching self.
Cri du chat Chromosome 5 pair
•The critical region of the chromosome containing genes which are responsible for the main features of the syndrome appears to be located in band 5p15.2.
•The gene causing the cry has been located in band 15.3.
•This would explain why some babies with other features of the syndrome do not have the characteristic cry and some babies have the cry but not the other characteristics.
What is Cri Du Chat Syndrome?
•Cri Du Chat Syndrome results from the loss or deletion of a significant portion of the genetic material from the short arm of one of the pair of number five chromosomes.
•is also known as 5P Minus syndrome and Cat's-cry syndrome.
•Where does the abnormal chromosome 5 come from?
•Multiple genes are missing as a result of this deletion, and each may contribute to the symptoms of the disorder. One of the deleted genes known to be involved is TERT (telomerase reverse transcriptase).
• This gene is important during cell division because it helps to keep the tips of chromosomes (telomeres) in tact
• It is thought that more girls than boys are born with the syndrome. The ratio is currently estimated to be 3 girls to 2 boys.
Facts About Cri-Du-Chat Syndrome
•The geneticist Jerome Lejeune identified cri-du-chat syndrome in 1963.
•He also discovered the genetic abnormality that causes Down syndrome.
•Cri-du-chat is one of the most common syndromes caused by a chromosomal deletion.
•Between 1 in 20,000 and 1 in 50,000 babies.
•In 80 percent of the cases, the chromosome carrying the deletion comes from the father's sperm rather than the mother's egg.
• When deletions occur during the formation of an egg or sperm, it is caused by unequal recombination during meiosis.
•When unequal recombination occurs at this location on chromosome 5, it causes cri-du-chat syndrome.