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.