P258: Phenotypic predictors of dual genetic diagnosis in people with autism

A major goal of SPARK (Simons Foundation Powering Autism Research for Knowledge), a cohort with sequencing data on 58,247 individuals with autism, is to return new genetic diagnoses related to autism. Previous analyses have shown that SPARK identified at least one likely pathogenic/pathogenic (LP/P) variant in 8.6% of autistic individuals, but the phenotypic presentations of people with more than one LP/P variant has not been investigated. The objective of this study was to characterize the phenotype of 102 individuals with two LP/P variants related to autism to identify phenotypic features that distinguish individuals with dual diagnoses.