Koolen de Vries syndrome is a disorder characterized by developmental delay, mild to moderate intellectual disability, congenital malformations, and behavioral features. Developmental delay is noted from an early age. Other problems include weak muscle tone (hypotonia) in childhood, recurrent seizures (epilepsy), and distinctive facial features. Males with Koolen de Vries syndrome often have undescended testes (cryptorchidism). Other symptoms may include defects in the walls between the chambers of the heart (septal defects) or other heart defects, kidney problems, and skeletal anomalies such as foot deformities. It is caused by mutations in the KANSL1 gene, or by the loss of a small amount of genetic material in chromosome 17 that includes the KANSL1 gene (chromosome 17 q21.31 microdeletion). Inheritance is autosomal dominant. Treatment may include physiotherapy, speech therapy, and educational programs, as well as medication for epilepsy and surgical treatment for malformations needing to be corrected.
Last updated: 3/3/2017
How is 17q21.31 microdeletion syndrome diagnosed?
17q21.31 microdeletion syndrome is diagnosed in individuals who have a deletion of 500,000 to 650,000 DNA building blocks (base pairs) at chromosome 17q21.31. The diagnosis can be made by various genetic testing methods, including FISH and array CGH. This condition cannot be diagnosed by traditional chromosome tests (karyotype) that look at chromosome banding patterns under the microscope because the deletion is too small to be detected.
Last updated: 5/4/2010
Where can I find addtional information on 17q21.31 microdeletion syndrome?
You can find more information about 17q21.31 microdeletion syndrome from Genetics Home Reference, the U.S National Library of Medicine's Web site for consumer information about genetic conditions and the genes or chromosomes related to those conditions. This resource also provides descriptions of genetic concepts, a glossary of genetic terms, and links to other genetic resources.
A fact sheet on 17q21.31 microdeletion syndrome is also available from an organization in the United Kingdom called Unique.