This is so that, when an egg and a sperm meet during conception, the child that is produced also has 46 chromosomes in each cell.
New body cells are produced for growth and repair by cells dividing, producing two 'daughter' cells.
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).
Other features may include learning difficulties and slow growth and development. However, physiotherapy, speech and language therapy, and surgical treatment for some abnormal features may be needed.
Many affected children will survive well into adulthood.
Possible problems include too many chromosomes, too few chromosomes or damage to one or more chromosomes.
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.However, those babies severely affected may die within the first year of life.Chromosomes are found in the centre (nucleus) of a cell.