De novo 4q35.2 duplication containing FAT1 is associated with autism spectrum disorder

Abstract Genetic studies have established a connection between FAT1 (FAT atypical cadherin 1) deletion and variants and autism spectrum disorder (ASD). Here, we describe a 7‐year‐old girl who sought a neurology consultation in order to be evaluated for ASD and was found to have a de novo 4q35.2 duplication containing the FAT1 gene. Similar to other reported cases of FAT1 variants or deletion, this patient exhibits non‐syndromic ASD without facial dysmorphism or brain MRI abnormalities. We suggest also considering FAT1 duplication as a potential ASD cause.