Each chromosome can duplicate an exact copy of itself so that each new cell that is formed has a full, identical set of chromosomes.Rarely, there is a problem with the child's chromosomes.
Cri du chat syndrome is a chromosome problem caused by a missing piece of chromosome 5.
The syndrome is called cri du chat (French for cry of the cat) because affected babies often have a high-pitched cry.
The other 22 pairs of chromosomes are numbered according to size with 1 being the longest pair and 22 being the shortest pair of chromosomes.
However, egg and sperm cells only have 23 chromosomes (1 chromosme from each pair).
Females have two of the same kind of sex chromosome (XX). The Y chromosome contains the male determining genes.
So, a normal female is 46, XX and a normal male is 46, XY.Each cell of your body contains chromosomes which are made up of many genes.In general, each cell in your body contains 46 chromosomes arranged in 23 pairs.They carry genetic information in the form of genes.'Genetic' means that the condition is passed on through families by special codes called genes.See the separate leaflets called Amniocentesis, Chorionic Villus Sampling and Ultrasound Scan.