Glossary

The way that physical and behavioural traits and characteristics are passed from biological parents to offspring through the mixing and recombination of genetic material that occurs at fertilisation.

Heritability is the extent to which a condition or feature can be attributed to genetic influences. If a condition is highly heritable, it means, for instance, that parents may pass on to their children genetic variants linked to heightened risk of developing autism. Genetic variants linked to autism may also arise afresh (through new mutations) without being inherited from parents.

Except in rare cases, autism is genetically heterogeneous: the genes that play a role in one individual’s autism are likely to be different from the genes involved in another individual’s autism.

A term used by some specialists to describe cases of autism where the individuals’ full-scale IQ scores are above 70. This is not a formal diagnostic category, but rather a term sometimes used informally in diagnosis, as well as in everyday situations and research. It has sometimes been used interchangeably with Asperger syndrome. The overlap between the two meanings has been questioned, and 'high-functioning' may also give the misleading impression that an able person's experience of autism is mild and not disabling. See also low-functioning.

A group of chemical substances that play a major role in transmitting signals around the body, helping to regulate physiological activities such as digestion and respiration, and psychological states such as stress, mood and social bonding.

All the genetic information carried by the DNA sequences which make up the chromosomes of each human cell.

A prediction about the results of an experiment, based on previous theory and findings concerning the phenomena that the experiment is designed to investigate. The hypothesis is formed before the experiment takes place.

A term used for the insights contributed by people with autism based on their own experience of the condition.

The overall score that a person achieves on a standardised test of verbal and non-verbal abilities, which indicates how well they perform in comparison to others of the same age.

The World Health Organisation's formal system for the classification and diagnosis of physical, psychiatric, mental health and developmental conditions. The current edition (ICD-10) reflects the older sub-type approach to diagnosing autism, whereas the next edition (ICD-11) due in 2018 will be more aligned with the DSM-5 approach.