Short answer · Medically reviewed summary · Last updated: 2026-05-08
Koolen-de Vries syndrome (KdVS), also known as 17q21.31 microdeletion syndrome, is a multisystem genetic condition characterized primarily by developmental delay, intellectual disability, and a distinct facial appearance. Symptoms vary significantly between individuals, but typically include neonatal hypotonia, epilepsy, and characteristic behavioral traits such as a friendly, sociable personality. What are the characteristic symptoms of Koolen-de Vries syndrome? The clinical presentation of Koolen-de Vries syndrome is broad.
Which are the symptoms of Koolen De Vries Syndrome / 17q21.31 Microdeletion Syndrome?
Symptoms of Koolen De Vries Syndrome / 17q21.31 Microdeletion Syndrome reported by real patients, from the most common to the most limiting, plus a medically reviewed summary with sources.
Koolen-de Vries syndrome (KdVS), also known as 17q21.31 microdeletion syndrome, is a multisystem genetic condition characterized primarily by developmental delay, intellectual disability, and a distinct facial appearance. Symptoms vary significantly between individuals, but typically include neonatal hypotonia, epilepsy, and characteristic behavioral traits such as a friendly, sociable personality.
What are the characteristic symptoms of Koolen-de Vries syndrome?
The clinical presentation of Koolen-de Vries syndrome is broad. Most individuals exhibit mild-to-moderate intellectual disability and delayed speech development. A hallmark of Koolen-de Vries syndrome is the "Koolen-de Vries facies," which includes a high forehead, down-slanting palpebral fissures, a bulbous nose, and a thin upper lip. Common clinical manifestations include:
- Developmental delay and intellectual disability (nearly 100% of cases).
- Neonatal hypotonia (low muscle tone).
- Epilepsy or abnormal EEG findings (seen in approximately 50% of patients).
- Congenital malformations, including heart defects (often septal) and urogenital anomalies.
- Friendly, social, and cooperative temperament.
How do symptoms progress and vary in daily life?
In Koolen-de Vries syndrome, symptoms often evolve from infancy through adulthood. While low muscle tone is prominent in early childhood, it may improve with age. Conversely, the social and behavioral aspects of Koolen-de Vries syndrome become more apparent as children reach school age. Daily quality of life is most significantly impacted by communication challenges and learning disabilities, which require early intervention, such as speech and occupational therapy. Because the 17q21.31 deletion affects gene expression, the severity is highly variable even within the same family, making personalized monitoring essential.
When should families seek immediate medical attention?
Families should seek urgent care if an individual with Koolen-de Vries syndrome experiences prolonged or new-onset seizures, unexplained regression in developmental milestones, or signs of acute cardiac distress. Given the risk of structural heart defects, any unexplained fainting or shortness of breath requires prompt evaluation by a cardiologist.
Next steps
- Consult with a clinical geneticist to confirm the diagnosis via chromosomal microarray.
- Join the DiseaseMaps.org community to connect with other families currently navigating Koolen-de Vries syndrome.
- Schedule routine screenings for heart, kidney, and vision health.
- Engage with early intervention programs, including physical, occupational, and speech therapy.
Medical disclaimer: This information is for educational purposes only and does not replace professional medical advice, diagnosis, or treatment.
References
- NIH Genetic and Rare Diseases (GARD) Information Center: Koolen-de Vries syndrome.
- Orphanet: 17q21.31 microdeletion syndrome.
- OMIM (Online Mendelian Inheritance in Man): #610443.
- Koolen-de Vries Syndrome Foundation (kdvsfoundation.org).
