DNA copying error in autism sufferers discovered

Rubicon winner Dalila Pinto discovered a copying error in the DNA of trial subjects who suffered from autism or a similar condition. Some segments of their DNA were copied either once too often or missed out of the copying process. This is a highly promising result from the world's largest investigation into autism. The top journal Nature placed the results online on 9 June.

About one child in every 110 suffers from autism or a condition on the autistic spectrum: PDD-NOS or Asperger's syndrome. The condition only manifests itself at the age of about 2 or 3, and there is no cure. Dalila Pinto and her co-researchers on the international 'Autism genome project' investigated the DNA of nearly 1000 autism patients. They discovered a completely new set of 'broken' genes that might cause autism, including some genes that might enable early diagnosis.

The errors in the DNA are the result of incorrect copying. A new copy of the DNA is required for every new cell. Your body therefore continually produces new DNA copies. This goes wrong once in a while for everyone. A part of the DNA is then copied either once too often or else missed out of the copying process. This can cause genetic short-circuits. The researchers discovered that this type of copying error occurs much more often in patients with autism.

Autism and leaning difficulties

Patients with autism have difficulty with social interaction and communication, and get embroiled in repetitive behavioural patterns. The notion that autism patients automatically have some sort of learning disability has long held sway, despite the fact that the contrary has been shown to be the case for many years now. In reality, autism patients vary widely in terms of their intellectual development. Some have above average intelligence, while others do indeed suffer from a learning disability. Pinto discovered a possible source of this earlier misconception: there is a significant overlap between the autism genes and genes that used to be associated with leaning difficulties. Leaning difficulties and autism may therefore be caused by the same genes.

The researchers discovered that a number of the newly found autism genes are part of the same genetic path. The genes in this type of path have comparable functions, or work together in some other way to fulfil important biological functions, for example in the brain. The fact that the different autism genes play a part on the same genetic paths offers new potential angles of approach for treatments.

More than 1500 families and 120 scientists were involved in this unique research project. They also investigated entire families where, for instance, the parents did not have autism but the children did. This led the researchers to discover that some of the copying errors are hereditary, but a substantial proportion of them occur only in the children.

Early diagnosis

The results of this research indicate that the cause of autism is not to be found in a few deviant genes shared by all autism patients, but rather in a wide variety of uncommon deviations. As the researchers map more possible variants, they gain a better chance of being able to explain the causes of autism. The researchers found genetic indicators in about 10% of the families they investigated, which might help in diagnosing autism at an early stage.

Source:

Nature

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