Refers to the influence that genes have on physical and psychological traits. Gene variants inherited from one or both biological parents influence susceptibility to autism.

The term for a condition or disorder in which variants of different genes are involved in different individuals. 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.

Within a programme launched by the Ethiopian Ministry of Health in 2004, health extension workers are women who have received one year of training in delivering primary healthcare. They work in rural areas from simple health posts, providing inoculations, health advice and basic treatments.

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.