Definition
Cri Du Chat is a dominant autosomal trait. It arises from the absence of a particular portion of chromosome 5. The absence of genetic material is called a deletion. Children born with this deletion in chromosome 5 have a characteristic mewing cry as newborns that is thought to be caused by abnormal development of the larynx (the organ containing the vocal chords). For this reason, the disorder is called cri du chat (or cat's cry) syndrome. In reference to the deletion and the area where it occurs, the disorder is also called 5p- (5 p minus) syndrome. Children with this syndrome have physical abnormalities, language and motor skill difficulties, and varying degrees of mental retardation. Cri du chat syndrome is a very rare disorder.

Description
The original genetic material is arranged into 23 pairs of chromosomes--one set of 23 chromosomes is inherited from each parent. Using a microscope, distinct chromosomes can be seen at a certain point in a cell's life cycle. When treated with certain stains, each chromosome bears a typical banding pattern, reminiscent of the stripes on a tabby cat's tail. Using each chromosomes' unique size and banding pattern, chromosomes 1-22 and the sex chromosomes, X and Y, can be identified exactly.

Although all individuals have two copies of chromosome 5, the normal chromosome does not compensate for the genetic material missing from the flawed chromosome. The deletion can be inherited through generations of a family or it may appear at random. It has been estimated that the syndrome occurs in 1 in 50,000 births. According to the 5p- Society, approximately 50-60 children are born with cri du chat syndrome each year in the United States.

My loving sister sarah, who has Cri Du Chat, but has been blessed with so many other great qualities.