Koolen de Vries syndrome


Disease Overview

Koolen de Vries syndrome is a disorder characterized by developmental delay, mild to moderate intellectual disability, congenital malformations, and behavioral features.[2373][13141] 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.[2373] 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).[13141][13142] 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.[13141]


  • 17q21.31 deletion syndrome
  • Monosomy 17q21.31
  • Microdeletion 17q21.31 syndrome
  • Chromosome 17q21.31 microdeletion syndrome
  • 17q21.31 microdeletion syndrome
  • KANSL1-Related Intellectual Disability Syndrome

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National Organization for Rare Disorders