Duplication 15q Syndrome

Maternal 15q duplication syndrome, otherwise known as Dup15q, is a neurogenetic condition of unknown prevalence in the general population but affects up to 0.2–3% of individuals with autism spectrum disorder (ASD). Dup15q is caused by at least one extra maternally derived copy of the Prader-Willi/Angelman Critical Region (PWACR) within chromosome region 15q11.2–q13.1, arising from either an isodicentric supernumerary chromosome or from an interstitial duplication. Common physical features are typically subtle and include down-slanting palpebral fissures, a depressed nasal bridge, and micrognathia. Individuals with Dup15q almost universally exhibit developmental delay in early childhood with moderate-to-severe intellectual disability. Compared to their non-syndromic autistic counterparts, Dup15q individuals with ASD may have a preserved responsive social smile and directed facial expressions. Neurodevelopmental co-occurring conditions and epilepsy tend to be present and are more severe with the isodicentric supernumerary subtype. Common psychiatric comorbidities include inattention, hyperactivity, anxiety, aggression, self-injurious behavior, and mood lability. Carbamazepine has been effective in improving some behavioral symptoms in a small number of patients.