Project information 

Autism spectrum disorder phenomenology in Phelan-McDermid syndrome

Supported by UNIQUE from 2011 – 2013

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Recent research into genetic disorders has been enhanced from advances in molecular genetics, enabling links to be made between groups of individuals with a specific genetic syndrome and the behaviours shown by individuals with that genetic syndrome. The nature of this gene-behaviour relationship has led to the introduction of the concept of ‘behavioural phenotypes’. Defining the behavioural phenotype for a syndrome provides a basis for clinical management and as behavioural phenotypes become more refined, it is also possible for predictors of later clinical problems to be identified earlier and for useful clinical interventions to be tailored.

Phelan-McDermid syndrome is a rare genetic syndrome associated with a deletion on chromosome 22q13. There is emerging evidence beginning to detail some of the medical and genetic features of Phelan-McDermid syndrome. These features include intellectual disability, generalised hypotonia, absent or severely delayed speech, and normal to advanced growth. However, despite the utility of defining behavioural phenotypes, there has been little research detailing the behaviours associated with Phelan-McDermid syndrome. A key behavioural feature reported in Phelan-McDermid syndrome is that of autism spectrum disorder behaviours. Identification of the presence of ASD is critical in order to ensure appropriate clinical support and educational placements. Consequently, there is a need to describe the behavioural phenotype of Phelan-McDermid syndrome, with a specific focus on the prevalence and characteristics of ASD impairments in this population.


To describe the characteristic behaviours associated with Phelan-McDermid syndrome with a specific focus upon the prevalence and nature of autism spectrum disorder behaviours


This project will have two stages. Recruitment for the first stage of the project has now begun. For the first stage of the study, carers of individuals with Phelan-McDermid syndrome, identified through UNIQUE, will be asked to complete a questionnaire pack. The questionnaire pack will include measures of mood, hyperactivity, repetitive behaviours, challenging behaviours and social functioning. Broad comparisons will be made between individuals with Phelan-McDermid syndrome and contrast groups of individuals with other rare genetic syndromes on these measures.
Following the questionnaire study, individuals with Phelan-McDermid syndrome will be contacted and invited to take part in the second phase of the study. This experimental study will specifically assess the types of ASD behaviours shown by individuals with Phelan-McDermid syndrome. A standardised observational assessment of ASD behaviours in individuals with Phelan-McDermid syndrome will be conducted.

Contact details

Caroline Richards

Chris Oliver