Sotos syndrome is a congenital overgrowth disorder with an incidence of approximately 1 in 14,000. The syndrome is associated with intellectual disability. Our recent review of research focusing on cognition and behaviour in Sotos syndrome identified several behavioural issues that may be common in individuals with Sotos syndrome. These were aggression and/or tantrums, autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD) and anxiety. Previous research has identified that there may be an association between Sotos syndrome and ASD but the majority of studies have explored this relationship using small groups of individuals with Sotos syndrome. The aim of our research was to investigate this relationship in a large group of individuals with Sotos syndrome.
ASD is a developmental disorder which is characterised by social communication impairment and restricted interests and repetitive behaviours. Many syndromes have been identified as having an association with ASD (e.g. Fragile X syndrome, Cornelia de Lange syndrome and Angelman syndrome). In order to better understand behaviour in Sotos syndrome, we investigated whether individuals with Sotos syndrome experience difficulties with social skills, restricted interests and repetitive behaviours. These are behavioural issues that are typically observed in individuals with ASD.
Our research involved 78 individuals with a diagnosis of Sotos syndrome. Families were invited to take part in the research via the Child Growth Foundation (CGF; a UK charity that supports families of individuals affected by growth disorders) and advertisements on Sotos syndrome support groups on social media. Behaviour was assessed using a questionnaire which was completed by a family member of the individual with Sotos syndrome - The Social Responsiveness Scale, second edition (SRS-2). This questionnaire has 65 questions which relate to social skills, restricted interests and repetitive behaviours.
A key finding from the research was that 65 of the participants (83.33%) were rated by their family member as experiencing difficulty with behaviours related to social skills, restricted interests and repetitive behaviours. This suggests that the majority of individuals with Sotos syndrome experience difficulty with behaviours that are associated with ASD. There was no difference in scores between males and females with Sotos syndrome which indicates that gender does not affect the presence of these behaviours in individuals with Sotos syndrome.
As we had individuals with a wide age range in our research (2.5 – 50 years), we decided to see if age affected behavioural issues in Sotos syndrome. We split our participants into five age categories and compared the average score for the individuals in each category. We found a significant difference in scores between the categories, with more prominent behavioural issues reported in childhood (5 – 19 years), compared with early childhood (2.5 – 5 years) and adulthood (20 years and older). This suggests that behavioural issues in Sotos syndrome may improve with time, as an individual transitions into adulthood.
The findings from this research suggest that the majority of individuals with Sotos syndrome experience difficulty with social skills, restricted interests and repetitive behaviours. These behavioural issues are typically associated with ASD and it therefore seems that there is a significant relationship between Sotos syndrome and ASD.
For the full paper, please see:
Lane, C., Milne, E. & Freeth, M.(2016). Characteristics of ASD in Sotos syndrome. Journal of autism anddevelopmental disorders. DOI: 10.1007/s10803-016-2941-z