Development and Adaptive Function in Individuals With SCN2A-Related Disorders

Area of Science:

• Neuroscience
• Genetics
• Developmental Biology

Background:

• SCN2A-related disorders commonly cause developmental impairment, but detailed descriptions are limited.
• Understanding developmental trajectories and adaptive function is crucial for managing these complex neurological conditions.

Purpose of the Study:

• To determine the developmental trajectories and adaptive function outcomes in individuals with SCN2A-related disorders.
• To identify distinct phenotypic subgroups within SCN2A disorders for prognostic and clinical trial purposes.

Main Methods:

• A retrospective cross-sectional study of 100 individuals from an international SCN2A Natural History Study.
• Individuals were grouped by SCN2A intragenic variants (early-onset/late-onset) or 2q24.3 copy number variants (CNVs).
• Developmental history, adaptive function (VABS-3), and behavior were assessed using parent/caregiver reports and medical records.

Main Results:

• 91% of individuals experienced developmental delay or intellectual disability; 29% had autism spectrum disorder.
• Significant delays were observed in motor (55% walking) and communication skills (31% speaking >1-5 words).
• Phenotypic subgroups (early-onset, late-onset, CNV) showed distinct adaptive behavior scores, with earlier seizure onset correlating with poorer motor function.

Conclusions:

• SCN2A-related disorders present a wide spectrum of developmental impairments and adaptive function challenges.
• Identifying specific phenotypic subgroups provides valuable prognostic information.
• These findings are critical for informing the design of targeted clinical trials for SCN2A disorders.