15q11-q13 duplication syndrome
15q11-q13 duplication syndrome (dup15q syndrome) is a developmental disorder caused by an extra copy of a region on chromosome 15, leading to varied signs and symptoms including poor muscle tone, intellectual disability, and a high incidence of autism spectrum disorder and seizures.
Overview
15q11-q13 duplication syndrome (dup15q syndrome) is a developmental disorder; its signs and symptoms vary among affected individuals.
Poor muscle tone (hypotonia) is common in individuals with dup15q syndrome and contributes to delayed development and impairment of motor skills, including sitting and walking. Most affected children develop the ability to walk independently after age 2 or 3, and they typically have a wide-based or uncoordinated (ataxic) pattern of walking (gait). Babies with dup15q syndrome often have trouble feeding due to weak facial muscles that impair sucking and swallowing.
Intellectual disability also occurs in people with dup15q syndrome and can range from mild to profound; however, it is usually in the moderate to severe range. Speech and language development are particularly affected, with some individuals never developing functional speech. Most individuals with this disorder have autism spectrum disorder (ASD), and many have language problems associated with ASD such as repeating the words of others (echolalia) or repeating particular phrases (stereotypical utterances).
Behavioral difficulties are also associated with dup15q syndrome, including other features of ASD such as difficulty with changes in routine and problems with social interaction. Affected individuals may also experience hyperactivity, anxiety, and frustration leading to tantrums. Mood disorders and psychosis occur in some affected individuals.
More than half of people with dup15q syndrome have recurrent seizures (epilepsy). The seizures usually develop between the ages of 6 months and 9 years. Some people with dup15q syndrome have only focal seizures, which affect one part of the brain and usually do not cause a loss of consciousness. In other affected individuals, seizures begin with a type called infantile spasms (seizures that usually appear before the age of 1 and involve recurrent muscle contractions) and later include other types of seizures. In addition to focal seizures, these can include rapid uncontrolled muscle