Understanding Behavior in Phelan-McDermid Syndrome.

Area of Science:

• Neurodevelopmental disorders
• Genetics
• Behavioral science

Background:

• Phelan-McDermid syndrome (PMS), or 22q13.3 deletion syndrome, is a rare genetic disorder.
• Characterized by developmental delay, hypotonia, and speech impairment.
• Behavioral difficulties are common, but their interpretation is limited by a lack of contextual understanding.

Purpose of the Study:

• To present a structured, multidisciplinary assessment method for Phelan-McDermid syndrome.
• To interpret behavioral data within the context of cognitive, adaptive, and genetic factors.
• To enhance understanding of the neurodevelopmental phenotype in PMS.

Main Methods:

• Employed direct in-person neurodevelopmental assessments and contextual factor evaluations.
• Utilized parent-informed questionnaires alongside standardized assessments (Bayley-III, Vineland, ESSEON-R, CBCL).
• Sample included 33 children with PMS (average age 6.2 years).

Main Results:

• Observed significant variability in phenotypic presentation, including behavior, symptom expression, and severity.
• High prevalence of withdrawn behavior and attention problems noted.
• Over half of the children exhibited borderline or clinical symptoms consistent with Autism Spectrum Disorder (ASD).

Conclusions:

• Direct in-person assessments combined with contextual data provide more accurate interpretation of behavior in PMS.
• Understanding behavior requires considering developmental context, cognitive, and adaptive functioning.
• This approach enhances knowledge of the neurodevelopmental phenotype and informs treatment for rare genetic disorders like PMS.