Sporadic Dup15q Syndrome Presenting With Developmental Delay, Intellectual Disability, Attention-Deficit/Hyperactivity Disorder, and Epilepsy: A Case Report

Abstract

Chromosome 15q duplication (Dup15q) syndrome is a rare genetic disorder that presents with a range of psychiatric and neurological symptoms. To date, no cases have been reported involving a patient with a 300 kb microduplication on chromosome 15 presenting with developmental delay, intellectual disability, attention-deficit/hyperactivity disorder (ADHD), and epilepsy. We describe a 20-year-old male diagnosed with Dup15q syndrome at the age of nine. His early development was marked by congenital strabismus, global developmental delay, and intellectual disability, which required enrollment in a special education program until age 11. He also exhibited hyperactivity, aggression, and self-injurious behavior. Since then, both his motor and cognitive functions have progressively declined. At age 14, he was diagnosed with ADHD. Treatment with atomoxetine, methylphenidate, and risperidone provided partial symptom relief. However, escitalopram triggered episodes of severe tantrums and was subsequently discontinued. From the age of 16, he began experiencing epilepsy, characterized by focal seizures, generalized tonic-clonic seizures, and absence seizures. Valproic acid (VPA) was effective in significantly reducing his seizure activity. This case highlights that Dup15q syndrome associated with a 300 kb microduplication can predominantly affect the central nervous system and may respond favorably to atomoxetine, methylphenidate, risperidone, and VPA. Dup15q syndrome should be considered in the differential diagnosis of individuals presenting with developmental delay, intellectual disability, ADHD, and epilepsy.