What is the prevalence of Koolen De Vries Syndrome / 17q21.31 Microdeletion Syndrome?

Koolen-de Vries Syndrome (KdVS), also known as 17q21.31 microdeletion syndrome, is an ultra-rare genetic condition with an estimated prevalence between 1 in 16,000 and 1 in 55,000 individuals. While current data suggests these figures, the actual prevalence is likely higher due to historical underdiagnosis and the necessity of chromosomal microarray testing for identification.

What is the estimated prevalence and incidence of Koolen-de Vries Syndrome?

Koolen-de Vries Syndrome is considered an ultra-rare condition. Clinical literature, including data from Orphanet, suggests a prevalence range of 1:16,000 to 1:55,000. Because Koolen-de Vries Syndrome is caused by a specific deletion or mutation of the KANSL1 gene, it is often missed in standard clinical screenings, meaning the true incidence of new cases per year remains difficult to pinpoint accurately. At DiseaseMaps.org, we currently support a growing community of 8 members living with Koolen-de Vries Syndrome, reflecting the global rarity of this diagnosis.

Does gender, geography, or age impact Koolen-de Vries Syndrome diagnosis?

Koolen-de Vries Syndrome affects both males and females equally, with no reported ethnic or geographic predilection. Symptoms are typically identified in early childhood, making it primarily a pediatric diagnosis, though as diagnostic technology improves, more adults are receiving retrospective diagnoses. The clinical presentation of Koolen-de Vries Syndrome is consistent across populations, though the severity of intellectual disability and physical features can vary significantly between individuals.

Why is accurate data for Koolen-de Vries Syndrome challenging to obtain?

Several factors contribute to the difficulty in establishing precise prevalence for Koolen-de Vries Syndrome:

• Diagnostic Thresholds: The syndrome requires specific genetic testing (chromosomal microarray or targeted KANSL1 sequencing) that may not be ordered for children with mild developmental delays.


• Clinical Variability: Because the phenotype of Koolen-de Vries Syndrome can be subtle in some cases, many individuals remain undiagnosed or misdiagnosed with generic intellectual disability.


• Reporting Gaps: Rare disease registries are still evolving, and many cases are not captured in global health statistics.

Next steps

• Consult a clinical geneticist to confirm a diagnosis via chromosomal microarray or KANSL1 sequencing.


• Connect with the Koolen-de Vries Syndrome community on DiseaseMaps.org to share experiences and find peer support.


• Visit the Koolen-de Vries Syndrome Foundation for the latest clinical trial information and educational resources.

Medical disclaimer: This information is for educational purposes only and does not constitute medical advice, diagnosis, or treatment; always consult with a qualified healthcare provider regarding your specific medical needs.

References

• Orphanet (ORPHA:137648) - 17q21.31 microdeletion syndrome.


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


• OMIM (Online Mendelian Inheritance in Man) - #610443: Koolen-de Vries Syndrome.


• Koolen-de Vries Syndrome Foundation - Clinical and research resources.