Down's syndrome

Joanne Phillips, a woman with Down's syndrome

Down's syndrome is a genetic condition which affects about one in every 1,000 babies born in the UK.

Every child develops using the genetic information passed from parents - this is carried in units called chromosomes, and humans normally have 46.

However, most children with Down's syndrome have received an extra copy of chromosome 21, making 47 in all.

No-one knows fully why this should happen, although older mothers are known to be at slightly higher risk of having babies with Down's syndrome.

There are other forms of Down's, which account for only a small percentage of cases, in which other chromosomal variations are to blame.

Physical difference

The results of Down's are many and vary from person to person. It is impossible to tell at birth how severe any disability will be.

Physically, many babies with Down's syndrome will look slightly different to other children - for example, their eyes often slant upwards and outwards, and the back of the head may be unusually flat.

In addition, a large proportion, perhaps as high as 40% of babies with Down's syndrome will have some sort of congenital heart defect, such as a "hole in the heart".

Surgery to correct these, if necessary, takes the same form as operations given to babies who do not have Down's syndrome.

Experts are keen that all babies with Down's syndrome have their hearts assessed as soon as possible after birth to either confirm or rule out the presence of defects.

Developmentally, a child with Down's syndrome will have some level of learning disorder, although this can be very mild, simply slowing down the child's mental development rather than stopping it altogether.

Most children with Down's learn to walk, talk and read and write - as well as do many of the other things taken for granted with other children, such as ride a bike.

However, the presence of Down's means that parents do have to be watchful for various health problems.

Babies and children with the syndrome often have an immune system which makes them prone to infections, particularly chest and sinus infections.

Babies with Down's syndrome can also have problems regulating their temperature, and can have very dry skin.