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Characteristics of Autism Spectrum Disorder in Russell-Silver Syndrome
Russell-Silver syndrome (RSS) is a rare condition associated with slowed growth both prenatally and postnatally. It is estimated that approximately 60% of individuals with a clinical diagnosis of RSS have an identifiable molecular cause. The most common molecular abnormalities are loss of methylation on chromosome 11p15 (observed in 30 – 60% of patients with a clinical diagnosis) and maternal uniparental disomy for chromosome 7 (MUPD7) (observed in 5 – 10% of patients with a clinical diagnosis). Previous research has indicated that autism spectrum disorder (ASD) may be common in individuals with RSS and particularly in those with RSS MUPD7. However, to date, the prevalence of ASD in RSS has not been systematically investigated using standardised assessments.
Objectives:
The aim of this study was to identify the prevalence of ASD in RSS 11P15 and RSS MUPD7, using a quantitative measure of ASD symptomatology - the Social Responsiveness Scale, second edition (SRS-2).
Methods:
The SRS-2 is a 65-item questionnaire, designed to assess severity of ASD symptomatology and is consistent with the DSM-5 criteria for ASD. The parent/caregiver of each participant completed the SRS-2 for 37 individuals with a diagnosis of RSS 11P15 (mean age = 7.71 years, SD = 4.47) and 23 individuals with a diagnosis of RSS MUPD7 (mean age = 9.17 years, SD = 6.46).
Results:
As assessed by the SRS-2, 38% of participants with RSS 11P15 and 43% of participants with RSS MUPD7 scored above clinical cut-off for ASD (total T-score ≥ 60). The findings indicated that individuals with RSS 11P15 and individuals with RSS MUPD7 displayed similar severity of difficulty with social communication impairment. However, individuals with RSS MUPD7 had greater difficulty with restricted interests and repetitive behaviours, compared to individuals with RSS 11P15.
Conclusions:
Overall, the findings indicate that individuals with RSS 11P15 and individuals with RSS MUPD7 display increased prevalence of behavioural symptomatology associated with ASD. In addition, individuals with RSS MUPD7 display particular difficulty with restricted interests and repetitive behaviours.