SHELBIE Pate is a child in a billion - the lively four-year-old is one of only 100 children in the world with a potentially life-threatening condition.

Shelbie has partial trisomy 9P - the same chromosome deficiency which led to the death of her brother Charlie when he was just three months old. Youngsters have a one in a billion chance of having the condition.

"Every day she stays alive is a bonus," said her mum Vicki Williams, who lives in Caldicot with husband Nick, Shelbie and their three other children aged ten, eight and seven.

Her daughter was diagnosed with the condition when she was just three weeks old. She has to take 17 different drugs and is fed through a tube. "We don't really know what her prognosis is but she is doing really well even though her health is bad," said her mum "She can't sit or walk and she can't talk."

Shelbie also suffers from epilepsy. Charlie died nine years ago but Mrs Williams went on to have three more children despite the risk that they would also have the condition.

She said it was not a hard decision and she did not have any tests when she was pregnant to discover if they were carrying the condition as she does not believe in termination.

"Shelbie never keeps still, she constantly rolls. She is really full of life and really enjoys life," said her committed mum. The family have faced some difficulties since they moved to Monmouthshire from Bristol 18 months ago. Trying to get specialist equipment was difficult.

Her daughter will have to return to school in Bristol in September although Mrs Williams would like her to attend Maes Ebbw in Newport where the facilities would better suit Shelbie.

A spokeswoman for Newport council said Monmouthshire council had successfully applied to the city's LEA for a place at the school for Shelbie.

How disorder is caused

PARTIAL TRISOMY 9P is a chromosome disorder. Trisomy means three (tri) copies of a particular chromosome instead of the expected two.

People born with a trisomy condition will have a third or partial copy of a particular chromosome.

For example someone born with a third copy of chromosome 21 has a condition known as Down's Syndrome.

Trisomy 9 refers to the ninth chromosome being affected although because the condition is so rare it does not have another name. The 'p' refers to a particular arm of the chromosome - there is also a 'q' arm.

The condition can cause heart defects, physical abnormalities and learning difficulties.