Mol Cytogenet 2014 23;7(1):74. Epub 2014 Oct 23.
Institute of Human Genetics, Georg August University, Heinrich-Düker-Weg 12, 37073 Göttingen, Germany.
Background: Kleefstra syndrome is characterized by intellectual disability, muscular hypotonia in childhood and typical facial features. It results from either a microdeletion of or a deleterious sequence variant in the gene euchromatic histone-lysine N-methyltransferase 1 (EHMT1) on chromosome 9q34.
Results: We report on a 3-year-old girl with characteristic symptoms of Kleefstra syndrome. Array comparative genomic hybridization analysis revealed a 145 kilobases duplication spanning exons 2 to 10 of EHMT1. Sequence analysis characterized it as an intragenic tandem duplication leading to a frame shift with a premature stop codon in EHMT1.
Conclusions: This is the first description of an intragenic duplication of EHMT1 resulting in Kleefstra syndrome.