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Thursday, 20 January, 2000, 16:10 GMT
Gene test for learning disabilities

down's syndrome Scientists search genetic pattern to learning disabilities


A genetic test to pick up on learning disabilities in children is being investigated by researchers.

The test, if shown to be successful, would be quick and relatively cheap compared to current procedures.

Scientists at Edinburgh University will spend two years trialling the test, designed to detect tiny chromosomal abnormalities in children with a type of learning disability known as congenital global mental handicap (CGMH).

It could allow prospective parents whose children are likely to suffer from learning disabilities to decide whether they wish to go ahead with having a family.

Children who suffer from CGMH can also suffer from a number of physical conditions, and different types of problems can show up within the same family.

There are between 600 and 900 cases of CGMH diagnosed in Scotland alone each year. Charity Mencap estimates the UK figure could be around 6,000 annually.



The present methods available to detect CRYSTA are expensive and unsuitable for the analysis of the large number of cases of CGMH that are diagnosed every year
Dr David Fitzpatrick
Dr David Fitzpatrick, clinical geneticist and lead investigator for the study, says around 10% of cases are caused by a chromosomal abnormality such as the chromosome 21 problem responsible for Down's Syndrome.

A further 6% of cases, according to recent studies, are the result of tiny sub-microscopic abnormalities, labelled cryptic subtelomeric aneuploidy (CRYSTA).

Expensive

Dr Fitzpatrick said: "The present methods available to detect CRYSTA are expensive and unsuitable for the analysis of the large number of cases of CGMH that are diagnosed every year in Scotland."

The Scottish Executive's chief scientist's office has awarded a grant of more than 137,000 to evaluate the test - a fluorescence-based chain reaction on an enzyme, which uses blood samples taken from sufferers of the condition.

Dr Fitzpatrick's team will then be able to assess the prevalence of CRYSTA in children with previously unexplained cases of CGMH.

He added: "The identification of CRYSTA not only provides an explanation for the disorder, thus preventing further expensive diagnostic investigations, but also clarifies the recurrence risk and enables prenatal testing and carrier testing within families."

The researchers will also look at samples stored from 2,000 children with learning disabilities.

Brian McGinnis, special adviser for Mencap, welcomed the trial.

He said: "With genetic understanding we are finding ways of predicting what might happen. It helps people make informed choices whether they want to have children or not."

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See also:
12 Nov 99 |  Health
Gene clue to learning disability
28 Jun 99 |  Health
Gene test cuts out cystic fibrosis
01 Dec 99 |  Health
Autism gene link
20 Jul 99 |  Health
Pain is in the genes, says study

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