Cat’s Cry Syndrome

Cat’s cry syndrome is a genetic disorder that occurs due to chromosome deletion. Newborn babies that lost a part of the short arm of the 5th chromosome show a distinctive cat-like cry. Hence the French term “cri du chat” syndrome (which means cry of the cat). Here, let us learn more about this rare genetic disorder.

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Chromosomal mutation causes cat’s cry syndrome in human babies. A mutation is a spontaneous and permanent change in a chromosome or gene which usually produces a detectable effect in the concerned organism. This change is also inheritable to offspring.

Uses of Mutation – Though they are deleterious to organisms, they play a significant role in the process of evolution or origin of species. Mutations have also been used to develop certain profitable crop plant varieties.

History of Mutation – Mutation has been in existence for a longer period of time. It is one of the driving forces in deciding natural selection and evolution. The earliest record of mutation dates back to 1791, but the concept of mutation started to gain attention and popularity in the mid-20th century. Before Darwin’s era, scientists commonly believed in the concept of saltationism. This concept deals with large and sudden mutations from one generation to the other that often lead to speciation.

Cat’s Cry Syndrome – Overview

Cri du chat or cat’s cry syndrome is a rare genetic condition in which a considerable portion of chromosome 5’s short arm is absent or partially deleted. It mostly happens due to genetic errors that occur during early embryogenesis. Symptoms vary widely depending on the specific amount and location of the removed genetic material. Common symptoms include a peculiar scream that sounds like a cat meowing (cry of the cat), unusual facial characteristics, delayed development, and microcephaly. Microcephaly is a condition in which a baby’s head circumference is lower than anticipated. Affected children also show delayed learning skills as that requires muscle synchronisation and mental activity. Eventually, the kid has decreased intellectual ability.

Chromosome Deletion

Complete or partial deletion of a portion of the short arm of chromosome 5 (autosome) results in this cat’s cry syndrome. The babies with this syndrome have a distinctive cat-like cry, which was first described by Lejeune et al. in 1963.

It is also called partial monosomy or 5p monosomy. It is said to occur due to de novo mutation (deletion). This means the mutation has not been transmitted from the parents; instead, it occurred spontaneously due to an error in the foetus’s cell division and DNA replication process.

Cat’s cry syndrome karyotype – The standard designation for a non-metacentric chromosome’s short arm is p, which for the longer arm is q. A deletion is indicated by a superscript minus sign and added segments are indicated by a superscript plus sign. Hence, the karyotype of a cri du chat patient is 5p

Cat’s Cry Syndrome – Synonyms

  • Cri du Chat syndrome
  • CdCS
  • 5p- syndrome
  • 5p – monosomy
  • Lejeune syndrome

See more:Mutation – A Genetic Change

Symptoms of Cat’s Cry Syndrome

Children with this syndrome often have problems sucking and swallowing their food. The syndrome also shows several other signs and symptoms, which are as follows:

  • The characteristic sign of microcephaly (small head).
  • They have malformations in the larynx.
  • They show mental retardation (IQ below 20).
  • Presence of saddle nose, moon face and small mandibles.
  • Excessive drooling.
  • Malformed low-set ears.
  • Widely spaced eyes with skin tags in front.

The disorder occurs due to malformations in the early embryogenesis process. Thus there is no specific way to treat them. Occupational therapy and physiotherapy can be given for the betterment of the child.

Keep exploring BYJU’S Biology to learn more such exciting topics.

Also Check:

Difference between Substitution, Insertion and Deletion Mutations

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Frequently Asked Questions


What are genes and chromosomes?

Chromosomes are nucleoprotein structures in which the genes are arranged in a linear fashion. Genes are the fundamental physical as well as functional unit of hereditary. It is considered a carrier of genetic information from one generation to another. These genes are made of DNA (genetic material).

What are the different types of structural changes in chromosomes?

A structural change in the chromosome can happen due to deletion (missing chromosome), duplication (duplication of a portion), inversion (the segment rotates by 180Β°) or translocation (transfer of segments). It is also referred to as chromosomal aberrations or abnormalities. Cri du chat syndrome occurs due to chromosomal deletion.

What is monosomy?

Monosomy denotes the presence of abnormal chromosome numbers that can lead to genetic disorders and syndromes. The term monosomy is used when only one chromosome exists from a pair. Examples – Turner syndrome and Cri du chat syndrome (5p monosomy).

What is meant by mutation?

Mutation is any change in a chromosome or gene that produces a detectable change in an organism. Any change in the DNA nucleotide sequence will result in the corresponding change in the nucleotide sequence of mRNA. It affects the protein synthesis process; thus, the resultant amino acid sequence is also altered. The defective structural protein may adversely affect the trait controlled by the protein.

What is site-directed mutagenesis?

Site-directed mutagenesis refers to specific and intentional mutation change. It is a laboratory technique to introduce targeted mutations in the desired DNA sequence. It is mainly used to investigate protein activity. It also screens mutation at RNA, DNA and protein levels for a desired molecular property.