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Cri-du-chat, commonly known as Cat’s-cry syndrome, is an autosomal deletion syndrome concerning one of the chromosomes in chromosome pair 5.The homologous chromosomes in chromosome pair 5 contain approximately 181 million base pairs, which is about 6% of a cell’s overall DNA.There are an estimated 900-1,300 genes on chromosome 5, out of about 20,000-25,000 genes in total in DNA.However, in a child born with Cri-du-chat, 30%-60% of the genetic information located on the short arm of one of the chromosomes of the pair is lost.



Background Statistics:

vCri-du-chat is a very rare syndrome that occurs in about 1 out of every 50,000 successful births in America
vMore girls have the disease than boys, with the ratio being 3:2
vIn about 80% of the cases, the deletion was paternal on origin



But what causes Cri-du-chat?

Cri-du-chat is caused by when there is a missing or deleted piece on the short arm of one chromosome in pair 5.Today we know that the deleted part responsible for the disease is called band 15.2 on 5p. The letter “p” refers to the short arm of the chromosome, having stemmed from the French word for small being “petite”.Therefore, Cri-du-chat is denoted 5p-, showing that the deletion occurred on chromosome 5 in the short arm.

vIn 80% of the reported cases, Cri-du-chat is simply caused by a spontaneous deletion in chromosome 5
vHowever, 10-13% of the time, the syndrome can be linked back to an error in chromosome 5 in one of the parents

There are many different genetic arrangements that can account for the disease.For example, it could be caused by an unbalanced translocation, in which genetic material is lost due to a piece of a chromosome breaking off and not reattaching correctly or not reattaching at all.Or, Cri-du-chat can be caused by an inversion, in which a piece of a chromosome break off, flips upside down, and then reattaches itself.One very rare genetic arrangement that is particularly challenging to identify is known as mosaicism.In mosaicism, the chromosome with the deletion is only found in a certain percentage of the cells in the body.

This link has a lot of information about Cri-du-chat.If you scroll down until almost the very bottom of the page, then you can see pictures of people with Cri-du-chat as well as a couple karyotypes of people with the syndrome: Pictures and Karyotypes



So, what are the symptoms?

A variety of symptoms are linked with Cri-du-chat, including but not limited to:

vCat-like cry
oScientist have been able to identify band 15.3 on chromosome 5 as being responsible for this distinctive sound
o1/3 of the individuals with Cri-du chat lose the cry by age 2
vSmall head with a round face
vPetite, retreating chin
vEyes that are widely spaced apart
vFolds of skin over the upper eyelid along with deep-set eyes
vUnique creases on palms



Developmental Issues:

There are a pattern of developmental issues that are seen in most children with the Cri-du-chat syndrome.They include but are not limited to:

vIntellectual impairments
vSpeech and language issues
oIt has been proven that patients with Cri-du-chat understand on a higher level than they are able to communicate
vDelayed development concerning movement
vShort attention span (very common)
vHyperactivity
vRecurring, difficult behaviors
oSuch as head-banging and scratching
vSocial skills like those observed in 5 or 6-year-olds



Related Medical Problems:

Though many medical problems that are observed in Cri-du-chat patients cannot be directly linked to the disease, some extremely common ones include:

vHeart problems
vBowel issues (constipation)
vSwallowing difficulties, making it especially hard for patients to eat in the first few months
vHearing problems
vLow muscle tone (often thought to be the cause of the cat-like cry)



Diagnosis:

Diagnosing Cri-du-chat can be tricky, especially in people with the form related to mosaicism, because the deletion is not present in all cells.Therefore, the mosaicism is often diagnosed as a different disease before symptoms that define Cri-du-chat become clear.The first signs of Cri-du-chat usually present themselves in the child during the first trimester of pregnancy.If a doctor is suspicious of a medical problem such as Cri-du-chat after an ultrasound is performed, than testing for a disease is essential.The test used to detect the Cri-du-chat syndrome is known as CVS, or chrionic villus sampling.CVS is used to identify genetic abnormalities, and results can be available within one to seven days.



What treatment options are available?

There are currently no treatments available to help cure the actual Cri-du-chat disease, because there is no way to recover the genetic material that has been lost.However, there are certain therapies and other such intervention programs that can help the child grow up to live a fulfilling life and develop to its maximum potential.Some of these are:

vPhysiotherapy
oTreatment of physical disabilities
vSpeech therapy
oHelps child develop communication skills
o50% of children with Cri-du-chat are able to use sign language as an adequate form of communication
vOccupational therapy
oTherapy through repetitive productive activity
vBehavioral management
oHelps children with Cri-du-chat as well as their families cope with some of the difficult behaviors described above




Prognosis:

Though Cri-du-chat can affect children in ways ranging anywhere from mildly to severely, with the proper interventions and therapies they can all lead happy lives within their communities.As long as serious medical issues do not persist, many live well into adulthood.The mortality rate is relatively low, at 6%-8%, and 90% of the deaths occur within the first year.So, if a child is able to live out its first year, than it has a very good chance of surviving to become a valued adult.Patients with Cri-du-chat can even have children, although some of the risks of passing the syndrome on to offspring are high.In people who have the mosaicism form of Cri-du-chat, the real risk of passing it on to offspring presents itself only when the deletion is in the cells of the reproductive organs.In addition, if a parent has a balanced translocation, meaning that a piece of a chromosome has broken off but there is neither a loss nor a gain in genetic information, then there is an 8.7%-18.8% risk that any offspring will have Cri-du-chat.However, the chance of getting Cri-du-chat is still very rare.




What research is being done to support Cri-du-chat?

vMost research being done with Cri-du-chat is focused on the genetic aspects and defining which specific genes relate to which aspects of the syndrome
vBehavioral research is being performed on lesser scale to find more interventions and therapies to help treat the disease
vSome developmental research is being done as well to determine a way to predict how severely a child will be affected by Cri-du-chat

Hopefully, as genetic engineering methods progress, one day there will be a way to cure Cri-du-chat.Until then, scientists are doing the best they can to at least ensure the happiness of Cri-du-chat patients.

Here is a link to the 5p- Society website.It provides information and support for those who need to know more about Cri-du-chat: 5p- Society




Works Cited:
http://www.criduchat.asn.au/criduchat/what.htm
http://www.americanpregnancy.org/prenataltesting/cvs.html
http://www.emedicine.com/ped/topic504.htm
http://ghr.nlm.nih.gov/ghr/chromosome/5