Spanish researchers in largest-ever genetic autism study make ground-breaking discoveries

Some 35,000 individuals took part in the study, including people with Autism Spectrum Disorders (ASDs) and also mentally-disabled persons with neuro-developmental delay (NDD), plus confederates and scientists.

And 30 of the genes identified are completely new.

ASDs cover a multitude of neurological differences – there is some debate over whether Asperger is a form of high-functioning autism, and it is often the most 'invisible' on the spectrum as those with it lead normal lives and are often of very high intelligence and abilities, whilst other, more severe strains can mean the patient is, in medical and psychological terms, retarded (typically characterised as with an IQ of 70 or less) meaning they need round-the-clock care.

Some autistic people are non-verbal and show developmental delays, although at the higher-functioning end of the spectrum, advanced development is often a feature.

Mental disability or learning difficulties are not necessarily associated with autism per se, but the two often overlap in the severely-autistic.

Until now, it has often been questioned whether autism is passed on through generations – in the case of high-functioning autism, or Asperger's parents, their children will often receive the same diagnosis.

But the Gregorio Marañón study has found both 'rare', or unrelated, genes, as well as hereditary genes, involved in both ASDs and NDD.

In fact, the principal genes involved in ASDs are not inherited from either parent, the team reveals.

A group of 24 genes involved in neurological communication were found to affect individuals with Autism Spectrum Disorders exclusively, whilst another, wider group of 58 genes was found to be present in individuals with ASDs and generalised NDDs or mental disabilities combined.

In addition to the laboratory-based scientists, the research involved investigators from the Mental Health and Psychiatry Institute at the hospital – the autism team on the Child and Teenager Psychiatric Service played a major rôle in the Autism Sequencing Consortium (ASC).

The Gregorio Marañón has a complete and all-round programme for supporting ASD patients – a pioneering scheme that carries out over 3,000 consultations a year and receives around 300 new referrals every year.

Patients studied in the sequencing research partly came from this programme.

According to the report on the research, published in Cell magazine, the genetic study has enabled scientists to differentiate between the DNA makeup responsible for ASDs, and the genes that cause generalised NDDs.

The results appear to show that these two conditions exist independently, but that a combination of the two sets of genes are what leads to those with severe autism often being mentally disabled or suffering learning difficulties and slower development.

Diagnoses of autism have increased dramatically in recent years, due to improved methods of detecting the condition.

Much work is still needed in diagnosing autism, especially high-functioning autism or Asperger's, in women and girls, since the vast majority are overlooked.

Statistically, only 20% of people with autism or Asperger are female, since diagnosis focuses on 'male-brained' behaviour due to historic studies having used only male volunteers.

Photograph: The autism assistance team at the Gregorio Marañón Hospital, who took part in the sequencing study