Which are the causes of Koolen De Vries Syndrome / 17q21.31 Microdeletion Syndrome?

Koolen-de Vries syndrome (KdVS), also known as 17q21.31 microdeletion syndrome, is caused by a missing piece of genetic material on chromosome 17. This deletion typically includes the KANSL1 gene, which is essential for normal brain development and the regulation of various cellular functions throughout the body.

What causes Koolen-de Vries syndrome?

Koolen-de Vries syndrome is a genetic condition caused by a microdeletion of a small segment on the long arm of chromosome 17 (specifically at position 17q21.31). This region contains several genes, but the primary driver of the clinical features is the haploinsufficiency of the KANSL1 gene. When one copy of this gene is missing, the body cannot produce enough of the KANSL1 protein, which acts like a master switch for turning other genes on or off during development.

Is Koolen-de Vries syndrome inherited?

In the vast majority of cases, Koolen-de Vries syndrome occurs de novo, meaning it happens spontaneously during the formation of reproductive cells (sperm or egg) or in early embryonic development. It is rarely inherited from a parent. Because it is a chromosomal event, there are no known environmental, dietary, or lifestyle triggers that cause the condition.

How does the genetic deletion affect the body?

The loss of the KANSL1 gene disrupts complex biological pathways. Key impacts include:

• Neurological development: Affects cognitive processing and speech acquisition.


• Muscular tone: Often results in hypotonia (low muscle tone) in infancy.


• Structural variations: Can lead to specific facial features or cardiac anomalies.


• Epilepsy: A significant portion of individuals with Koolen-de Vries syndrome experience seizures.

Is the cause of Koolen-de Vries syndrome fully understood?

While we know the genetic mechanism—the deletion of 17q21.31—researchers are still working to understand exactly how the KANSL1 protein influences specific developmental outcomes. Current research focuses on how this gene regulates chromatin, the structure that packages DNA, to better understand why symptoms vary so widely among the 8 members currently sharing their experiences on DiseaseMaps.org.

Next steps

• Consult a clinical geneticist to confirm a diagnosis via chromosomal microarray analysis.


• Connect with the Koolen-de Vries syndrome community on DiseaseMaps.org for peer support.


• Discuss early intervention therapies, such as speech and physical therapy, with your pediatrician.

Medical disclaimer: This information is for educational purposes only and should not replace professional medical advice, diagnosis, or treatment.

References

• NIH Genetic and Rare Diseases Information Center (GARD): Koolen-de Vries syndrome.


• Orphanet: 17q21.31 microdeletion syndrome.


• OMIM (Online Mendelian Inheritance in Man): #610443.


• Koolen-de Vries Syndrome Foundation.