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Kleyner R, Malcolmson J, Tegay D, Ward K, Maughan A, Maughan G, Nelson L, Wang K, Robison R, Lyon GJ. KBG syndrome involving a single-nucleotide duplication in ANKRD11. Cold Spring Harb Mol Case Stud 2017; 2:a001131. [PMID: 27900361 PMCID: PMC5111005 DOI: 10.1101/mcs.a001131] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
KBG syndrome is a rare autosomal dominant genetic condition characterized by neurological involvement and distinct facial, hand, and skeletal features. More than 70 cases have been reported; however, it is likely that KBG syndrome is underdiagnosed because of lack of comprehensive characterization of the heterogeneous phenotypic features. We describe the clinical manifestations in a male currently 13 years of age, who exhibited symptoms including epilepsy, severe developmental delay, distinct facial features, and hand anomalies, without a positive genetic diagnosis. Subsequent exome sequencing identified a novel de novo heterozygous single base pair duplication (c.6015dupA) in ANKRD11, which was validated by Sanger sequencing. This single-nucleotide duplication is predicted to lead to a premature stop codon and loss of function in ANKRD11, thereby implicating it as contributing to the proband's symptoms and yielding a molecular diagnosis of KBG syndrome. Before molecular diagnosis, this syndrome was not recognized in the proband, as several key features of the disorder were mild and were not recognized by clinicians, further supporting the concept of variable expressivity in many disorders. Although a diagnosis of cerebral folate deficiency has also been given, its significance for the proband's condition remains uncertain.
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Affiliation(s)
- Robert Kleyner
- Stanley Institute for Cognitive Genomics, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
| | - Janet Malcolmson
- Stanley Institute for Cognitive Genomics, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA;; Genetic Counseling Graduate Program, Long Island University (LIU), Brookville, New York 11548, USA
| | - David Tegay
- Stanley Institute for Cognitive Genomics, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
| | - Kenneth Ward
- Affiliated Genetics, Inc., Salt Lake City, Utah 84109, USA
| | | | - Glenn Maughan
- KBG Syndrome Foundation, West Jordan, Utah 84088, USA
| | - Lesa Nelson
- Affiliated Genetics, Inc., Salt Lake City, Utah 84109, USA
| | - Kai Wang
- Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California 90089, USA;; Department of Psychiatry & Behavioral Sciences, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA;; Utah Foundation for Biomedical Research, Salt Lake City, Utah 84107, USA
| | - Reid Robison
- Utah Foundation for Biomedical Research, Salt Lake City, Utah 84107, USA
| | - Gholson J Lyon
- Stanley Institute for Cognitive Genomics, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA;; Utah Foundation for Biomedical Research, Salt Lake City, Utah 84107, USA
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