A new study published in the March issue of Autism Research from the University of Tennessee Health Science Center and Le Bonheur researchers is making the genetic connections between autism and Chromosome 15q Duplication Syndrome (Dup15q).
The Memphis researchers determined that the maternally derived or inherited duplication of the region inclusive of the UBE3A gene (also known as the Angelman/Prader-Willi syndrome locus) are sufficient to produce a phenotype on the autism spectrum in all ten maternal duplication subjects. The number of subjects was too small to determine if parental duplications do not cause autism. The team assembled the largest single cohort of interstitial 15q duplication subjects for phenotype/genotype analysis of the autism component of the syndrome.
Chromosome 15q Duplication Syndrome (Dup15q) results from duplications of chromosome 15q11-q13. Duplications that are maternal in origin often result in developmental problems. The larger 15q duplication syndrome, which includes individuals with idic15, manifests itself in a wide range of developmental disabilities including autism spectrum disorders; motor, cognitive and speech/language delays; and seizure disorders among others. While there is no specific treatment plan, therapies are available to address or manage symptoms.
Previous research suggests that as many as 1,000 genes may contribute to autism phenotypes, but as much as 1-3 percent of all autism spectrum disorder cases may be a result of 15q11-q13 duplication alone.
The researchers also found through EEG evaluations a pattern that looks like the type of signal you see when individuals take GABA promoting drugs (benzodiazepines). The lead researcher on this study, Lawrence T. Reiter, PhD, says this signal gives clinicians a clue about what types of anti-seizure medication may be most useful in children with 15q duplications.
Reiter says genetic testing can help families connect to resources, like the Dup15q Alliance. Reiter is an associate professor in Department of Neurology with an adjunct appointment in Pediatrics at UTHSC.
"If a pediatrician suspects autism due to hypotonia and developmental delay, I highly recommend they order an arrayCGH test. Duplication 15q is the second most common duplication in autism. The test will help families in future treatments specific to this sub-type of autism," he said.
Reiter collaborated with UTHSC and Le Bonheur Neurologist Kathryn McVicar, MD, and Geneticist Eniko K. Pivnick, MD. The study was funded by the Herbert and Mary Shainberg Neuroscience Fund. Reiter serves on the scientific advisory board for the Duplication 15q Alliance and Idic15 Canada.
- Nora Urraca, Julie Cleary, Victoria Brewer, Eniko K. Pivnick, Kathryn McVicar, Ronald L. Thibert, N. Carolyn Schanen, Carmen Esmer, Dustin Lamport, Lawrence T. Reiter. The Interstitial Duplication 15q11.2-q13 Syndrome Includes Autism, Mild Facial Anomalies and a Characteristic EEG Signature. Autism Research, 2013; DOI: 10.1002/aur.1284
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