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Cri du Chat
Transcript of Cri du Chat
What is Cri du Chat?
Jérôme Lejeune (1926-1994):
- before 1958: confirmed theory of Petrus Waardenburg -> Down's syndrome has genetic origin
- 1958: identified extra chromosome in Down's syndrome
- 1963: described cri-du-chat
Cri-du-chat is a genetic disease caused by the deletion of the 5p chromosome.
It's so named because of the signature "cat cry" young children have.
-Micrognathia of jaw
-Large epicanthal folds
-Unusually small head shape
- Severe Cognitive, speech and motor delays
-Severe communication difficulties common
-Therapists generally required
-Behavioral difficulties, e.g. repetitive movements, short attention span, tantrums and other 'querks.'
What Causes the Cat-Cry?
"The horse has the benefit of being both able and willing to carry us." Brigitte Bonardot, nurse in equitherapy
Orthosis: a force system designed to correct or compensate a bone deformity.
Microcephaly is a reduction in head size
Scoliosis is an abnormal spine curve
It's not specifically a genetic disorder and is generally progressive
Microcephaly & Scoliosis
Cri -du-Chat in the Media
-Currently there is no drug treatment for Cri -du-Chat Syndrome
-There have been no major breakthroughs since it's discovery in 1963
-Gene Therapy offers a possible 'cure' for all genetic disorders and could help with Cri-du-Chat
-Edvidence of Pontine Hypoplasia in MRI scans has been a recent tool in diagnosis - checks could become standard procedure in the future
-The internet gives sufferers access to more information and creates an online help community
- Affects 1 in 50,000
- Slight female predominance 4:3
- Accounts for 1% of all patients with learning difficulties
- Slightly lowered life expectancy
International awareness video
5p minus society
Cri du Chat Awareness week:
May 5th-May 9th 2015
- Ergotherapy: looks at everyday tasks, eg: orthosis
- Physiotherapy: improve muscle development
- Psychology: improve socialising skills
- Sign language: improve communication
- Surgery: for potential heart defects
- Equitherapy (see later slide)
- Art therapy (see later slide)
-Vast range of symptoms
-Variation between individuals caused by different genetic mechanisms
-Similarities to other diseases
-Symptoms are both physiological and mental
Internal Symptoms e.g. ASD, VSD & Malrotation of stomach
"Claire’s reaction to the move was initially rather unsettling for us all, with some extreme head banging which resulted in quite a bloody and bruised forehead. "
CTNND2 - Codes for Delta-Catenin.
- Helps adhere cells in CNS.
- Linked to mental retardation.
SEMAf - Codes for Semaphorin F
- Carries out a similar role to CTNND2
- Also linked to mental retardation.
hTERT - Codes for telomerase reverse transcriptase
- Important for maintaining telomeres during cell division.
- Causes a multitude of problems.
Most common deletion - Accounts for ~80% of patients.
Break in DNA with all genes upstream of that locus lost.
Two breaks in the chromosome with all genetic information between the two loci being lost.
Can lead to genes that would have otherwise been removed being present.
Accounts for ~10% of all Cri du Chat cases
Cri-du-Chat can cause many physiological changes to the larynx
Cat Cry normally goes away after 2 years
Corrective surgeries may be required for:
- heart defect
- malocclusion: orthodontic work
- strabismus: when one of the 6 muscles controlling each eye movement is stronger or weaker than the others → surgeon detaches and reattaches muscle
Causes ~10% of all Cri du Chat cases
DNA relocated either:
To a non-homologous chromosome or...
To a homologous chromosome and not carried on due to meiosis.
Parents who are at risk can be identified and receive genetic counseling.
No real treatment as no cure or drugs, but there are a large range of ways to improve life condition, such as:
- genetic counseling
Can be used to obtain cells shed from a foetus into amniotic fluid.
Karyotyping these cells can be used to diagnose congenital disorders, such as Cri du Chat and many others.
1% chance of miscarriage but may be worth the risk if the child is deemed to be at-risk.
hybridization) uses fluorescent markers, complementary to specific sections of DNA.
Allows for visualization of subtle defects to the chromosome when they would otherwise appear normal using less sensitive techniques.
Cells from amniotic fluid are broken down to extract DNA.
Condensed chromosomes from cells in interphase are stained.
Allows for rough observations of chromosomes - Substantial deletion & translocations become apparent.
The vast majority (80%) of cases are diagnosed by the age of one.
40% diagnosed in the first month.
Early diagnosis common due to distinctive features and symptoms.
Prenatal diagnosis is also possible but is more difficult using commonly used non-invasive techniques such as ultrasound.
Invasive techniques are more accurate but there are risks associated.
(Jo is a carrier)
"my mum and her friends who have kids like Frances, they have the sickest sense of humour. You've got to or you'll go under, you'll crack up."
How Are The Genes Are Lost?
of cases caused by two main types of
and not inherited.
of cases caused by
from parents who are at-risk.
Other 5% caused by various uncommon mechanisms.
*Figures from Italian healthcare records
Amount of DNA lost is proportional to the severity of symptoms