Cri-du-chat is French for the cry of the cat. This syndrome affects between 1 in 20,000 and 1 in 50,000 babies. It is more common to spot on females with a ratio of 4:3. Interestingly, there is a prevalence of 1:305 among patients attending genetic counseling services.
In 80% of the cases, the chromosome carrying the deletion is inherited from the father’s sperm rather than the mother’s egg.
Dr. Jerome Lejeune 1st described cri du chat syndrome (also known as Lejeune’s syndrome or chromosome 5p deletion syndrome) in 1963. With the help of the new karyotype techniques of the 1950s, Dr. Jerome Lejeune identified this syndrome as the absence of genetic material on the 5th chromosome. He also identified Down Syndrome.
Some patients with this disorder get gray hair earlier than most people.
It is possible to detect this syndrome with CVS (Chorionic Villus Sampling) or amniocentesis in the 1st trimester of pregnancy. Doctors can either test a sample of the amniotic fluid (amniocentesis) or a tiny sample of tissue from outside the sac where the baby develops (chorionic villus sampling – CVS).
Diagnosis after birth will be made by investigations if a baby has any symptoms suggesting the cat’s cry syndrome.
People affected by this genetic disorder can expect to live a normal lifespan, though they will display differing degrees of reliance on others for daily support.
A small percentage of infants with this syndrome are born with serious organ defects (particularly kidney or heart defects) or other life-threatening complications.
About one in 10 babies (10 percent) born with this disorder are severely affected and die within the 1st year of life. Intellectual disability is also common.
Most cases of cat’s cry syndrome seem to occur spontaneously for unknown reasons very early in embryonic development.
Causes of Cat’s Cry Syndromes
Abot 90 percent of cases result from a rare genetic disorder due to a missing part (deletion) of chromosome 5. Numerous genes are missing as a result of this deletion, and each may contribute to the symptoms of this syndrome.
Not all babies with the missing piece of chromosome 5 will develop this syndrome. Approximately 10% of them take place when an altered and unequal chromosomal arrangement is passed on from the parents to their child. In these cases, the severity of the symptoms observed in this syndrome is found to be even more intense.
The risk of a couple with normal chromosomes having another child with this syndrome is about 1%.The remainder of cases are caused by random chromosomal deletion during the generation of sperm and eggs or during fetal development.
Note – It is essential to understand that the degree and type of signs and symptoms are extremely variable between affected patients. Some individuals with genetically confirmed CCS have few of the symptoms and characteristics which are linked to this genetic disorder and may appear nearly phenotypically normal.
Babies with cat’s cry syndrome do not grow as fast as other children and have a low birth weight. Most of them have to deal with the feeding problems due to poor suck, low muscle tone, and gastroesophageal reflux disease.
In addition, affected babies experience speech, motor, and cognitive delay. However, they commonly understand speech better than they can communicate.
Some people with this syndrome have abnormally formed ears or have an extra skin fold near the eye.
Other symptoms include:
A single line in the palm of the hand (also known as the simian crease);
The baby has a cry that is high-pitched and has been described as sounding like a cat. This unusual cry is most of the times recognizable at birth.
Babies with this affection may experience difficulty swallowing and breathing;
Babies also may have a small head (better known as microcephaly), deformities of the skeleton (like the curvature of the spine – scoliosis), or a small jaw (also known as micrognathia).
There is no cure available for this syndrome; therefore, medical care is concentrated on the symptoms and developmental therapy, like – language skills, motor skills to help improve the quality of life of the patients.
Fifty per cent of the affected children learn plentiful verbal skills to communicate. Moreover, a few patients learn to use short sentences, while others express themselves with a few gestures, basic words, or sign language.
Heart abnormalities usually need surgical correction.
There is no known prevention of this rare syndrome. It is recommended for couples with a family history of this disorder who wish to have a baby to consider genetic counselling.