One region, three disorders. The following blogpost serves as a partner to this week’s earlier post on the genomic idiosyncrasies of the 15q11-13 region. We hope that the discussion of the clinical aspects of disorders rooted in this region will further illustrate the vast complexity of the genome. Below we describe the three clinical syndromes associated with this region.
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Chromosome 15q11-13: one region, many disorders
Cytogenetics. 15q11-13 can be an intimidating region, even for many seasoned genetics professionals. Several factors contribute to this, including a complex genomic architecture, genomic imprinting, an acrocentric chromosome, and several genes critical to neurological function. For today’s blog post, we’ll try to unravel some of its complexity to make interpretation of copy number variants (CNVs) in this area clearer.
Of angels and interneurons
Angelman Syndrome and UBE3A. Angelman Syndrome is a severe neurodevelopmental disorder characterized by intellectual disability, typical facial features and a usually happy demeanor. Patients with Angelman Syndrome usually do not acquire active speech and often show a characteristic, atactic gait. Also, patients with Angelman Syndrome have a characteristic EEG pattern and many children have seizures. Angelman Syndrome is a genetic disorder due to loss of function of UBE3A, a ubiquitin ligase expressed in the CNS. Ubiquitin ligases are the bin collectors of the cell. By attaching ubiquitin to proteins, proteins are labelled for cellular degradation. How a malfunction of a cellular garbage truck causes such a complex neurodevelopmental disorder is poorly understood. A recent study, however, points out an important role for interneurons…. Continue reading