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Cri du Chat syndrome, otherwise known as Cat's Cry syndrome or 5p minus syndrome, is a relatively rare genetic disorder that affects somewhere between 1 in 25,000 to 1 in 50,000 births. This condition, named by French geneticist Jerome LeJeune in 1963, is marked by a distinctive monotone, high-pitched cry resembling that of a cat's. It is thought to be caused by low muscle tone and structural abnormalities in the mouth and throat. Existing records show that Cat's Cry syndrome occurs equally among all racial, cultural, and ethnic groups, regions, and countries, and no single environmental factor has been implicated in the syndrome's frequency. However, records have shown that girls are more likely to be afflicted, with an estimated ratio of three girls to two boys.
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Cri du Chat and Genetics
A large majority of cases (approximately 80%) of Cri du Chat syndrome are caused by a spontaneous deletion of part of chromosome 5. In 10-15 % of cases the rare genetic disorder is inherited from a parent with a balanced translocation on chromosome 5. Whilst a balanced translocation may not cause medical problems for the carrier, they can be problematic when passed to the next generation and are known as unbalanced translocations. A chromosomal deletion is one such example of an unbalanced translocation.
It is the short arm of chromosome 5 that is missing and it contains a region that is part of an area known as band 15.2. However, the gene responsible for the distinctive cry is located in band 15.31, which is why some babies with this syndrome exhibit this cry and others do not, yet still exhibit other syndrome characteristics.
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Cri du Chat Characteristics
While babies with larger deletions will be more severely affected than those with smaller deletions in and above band 15.2, they all generally exhibit some or most of the major identifying characteristics, including:
Creases on the palms of the hands
Hypertelorism (widely spaced eyes)
Low broad nasal ridge - Low set ears
Microcephaly (small head)
Micrognathia (small, receding chin)
Other medical problems present in a small minority of children with Cri du Chat syndrome include heart defects, cleft palate, bowel and kidney abnormalities, scoliosis, hernias, minor hearing impairments, gastrointestinal abnormalities, "turned eye", gastric reflux, chronic constipation, frequent ear infections, and low muscle tone.
The developmental effects of the syndrome on the child vary widely, but nearly all children with this syndrome will exhibit a certain degree of intellectual disability, and delayed motor skill development, speech, and language acquisition. Fortunately, most medical issues associated with Cri du Chat are highly treatable, and early intervention programs including physiotherapy, behavioral management, and speech and language therapy have been proven to be extremely beneficial.