Presentation 12 – Dr Nadja Bednarczuk

SSBP Virtual Symposium 2023

Behavioural and Developmental Characteristics of SYNGAP1-Related Intellectual Disability

Presenting Author : Dr Nadja Bednarczuk

Abstract

Behavioural and Developmental Characteristics of SYNGAP1-Related Intellectual Disability

Bednarczuk N.¹, Wolstencroft J.¹, Housby H.¹, Lee I.¹, IMAGINE Consortium ID ¹, Skuse D.¹

¹UCL BRC Great Ormond Street Institute of Child Health, UK

Background: SYNGAP1 is associated with intellectual disability (SYNGAP1-ID), behavioural difficulties, and autism. The neuropsychiatric phenotype of SYNGAP1-ID has not been systematically/fully described. We aimed to compare the behavioural and developmental characteristics of children with SYNGAP1-ID to children with other monogenic causes of ID.

Methods: Participants were identified from the IMAGINE-ID study, a national study of neuropsychiatric risk in children with ID of known genetic origin. Thirteen individuals with SYNGAP1 variants (age 4-16 years; 85% female) were matched (2:1) with 26 controls with other monogenic causes of ID for chronological and mental age, sex, socio-economic deprivation, adaptive behaviour and physical health difficulties.

Caregivers completed the Development and Wellbeing Assessment (DAWBA) which provides DSM-5 diagnoses, as well as a physical health questionnaire.

Results: Children with SYNGAP1-ID were not more likely to meet criteria for autism (N_control=8 vs N_SYNGAP1=6; p=.35), attention-deficit hyperactivity disorder (N_control =4 vs N_SYNGAP1=2; p=1), generalised anxiety disorder (N_control =4 vs N_SYNGAP1=1; p=.49) or oppositional defiant disorder (N_control=0 vs N_SYNGAP1=1; p=.15) than controls.

Children with SYNGAP1-ID were more likely to be non-verbal (n= 8) than controls (n=6; p=<.01). SYNGAP1-ID children that were able to speak (n=5, M=3.25 years) achieved this milestone at the same age as controls (M=3.25 years; p=.84). However, caregiver-estimated language age was lower in SYNGAP1-ID (M=2.7 years) compared to controls (M=4.8 years; p=0.040). No difference in age of walking was observed between SYNGAP1-ID (M=2.3 years) and controls (M=2.2 years; p=.30). Seizures affected children with SYNGAP1-ID (n=11[84.6%]) more frequently than controls (n=2[7.6%], p=<0.001).

Conclusions: Children with SYNGAP1-ID have language difficulties beyond those observed in children with other monogenic variants when matched for developmental level. Early speech and language interventions should be provided to help address these difficulties.

Keywords: SYNGAP1, Intellectual Disability, Autism Spectrum Disorder, Language

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