Children with cri-du-chat syndrome (Wikimedia Commons)
French geneticist Jerome Lejeune is the person who discovered Cri-du-Chat syndrome in 1963. He is also the one who discovered the genetic basis of Down syndrome. Lejeune observed that babies born with this particular syndrome exhibit a distinctive monotonous, high-pitched cry resembling that of a cat’s. He named the disorder as “Cri-du-Chat”, the French for “cry of the cat.” It is estimated that 1 in 25,000 births has Cri-du-chat syndrome worldwide.
Babies born with Cri-du-Chat syndrome have structural abnormalities to their larynx which is the reason why their cry resembles that of a cat’s. Besides from the problem with the larynx there are other abnormalities observed in children with Cri-du-chat syndrome which include the following:
- Low birth weight
- Small head (Microcephaly)
- Small, receding chin (Micrognathia)
- Round face
- Widely spaced eyes (Hypertelorism)
- Fold of skin over the eyes
- Epicanthic folds
- Creases on the palms
- Short fingers
- Flat nasal bridge
- Mental retardation, aggression, hyperactivity
- Heart defects (e.g. ventricular septal defect)
- Cleft palate
- Scoliosis
- Hernias
- Bowel abnormalities
- Kidney diseases (e.g. hydronephrosis, renal ectopia, horseshoe kidneys)
- Hearing impairments
- Gastrointestinal diseases
- Frequent ear infections
- Low muscle tone
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Genetics of Cri-du-Chat Syndrome
Cri du chat syndrome chromosomal deletion illustration (Wikimedia Image)
Cri-du-Chat syndrome is caused by a break in the small arm of chromosome 5. Several genes are lost as a result of the breakage which occur during the development of sperm (spermatogenesis) or egg (oogenesis). If a sperm with the defect fertilizes a normal egg, the child will develop Cri-du-Chat syndrome. And if the egg has the defect while the sperm is normal, the child will develop the disorder. Take note that not all the sperms or eggs have the chromosomal break so parents who have a child with the disorder can still produce normal children. By chance, a child can inherit a broken chromosome if one of his/her parents has Cri-du-Chat syndrome.[ad#afterpost]