Caring for someone with this diagnosis? Eleplan keeps diagnoses, medications, documents and every specialist in one plan.
Start free with EleplanKoolen-De Vries syndrome
ORPHA:96169Malformation syndrome
Also called KdVS
What it is
A rare multisystem disorder characterized by neonatal/childhood hypotonia, mild to moderate developmental delay or intellectual disability, epilepsy, dysmorphic facial features, hypermetropia, congenital heart anomalies, congenital renal/urologic anomalies, musculoskeletal problems, and a friendly/amiable disposition.
Key facts
- Age of onset
- Antenatal, Infancy, Neonatal
- Inheritance
- Autosomal dominant
- Classified as
- Malformation syndrome
Signs and symptoms
Very common80–99%
19- Blepharophimosis
- Broad forehead
- Bulbous nose
- Coarse facial features
- Epicanthus
- Everted lower lip vermilion
- Global developmental delay
- High forehead
- Hypotonia
- Intellectual disability
- Long face
- Overfolded helix
- Prominent nasal bridge
- Protruding ear
- Ptosis
- Thick nasal alae
- Underdeveloped nasal alae
- Upslanted palpebral fissure
- Wide nasal bridge
Common30–79%
29- Abnormal cardiac septum morphology
- Abnormal heart morphology
- Abnormality of hair texture
- Abnormality of the dentition
- Aplasia/Hypoplasia of the corpus callosum
- Arachnodactyly
- Atrial septal defect
- Cardiomyopathy
- Chiari type I malformation
- Cryptorchidism
- Delayed speech and language development
- Feeding difficulties in infancy
- High hypermetropia
- High, narrow palate
- Hip dislocation
- Hypernasal speech
- Hypopigmentation of hair
- Hypospadias
- Intraventricular hemorrhage
- Joint hypermobility
- Microdontia
- Narrow palate
- Optic atrophy
- Overfriendliness
- Poor speech
- Seizure
- Strabismus
- Ventricular septal defect
- Ventriculomegaly
Sometimes5–29%
32- Abnormality of dental enamel
- Anxiety
- Attention deficit hyperactivity disorder
- Bicuspid aortic valve
- Cafe-au-lait spot
- Cataract
- Cleft palate
- Conductive hearing impairment
and 24 more in this range
These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.
Genes reported in subtypes
Orphanet records this gene on 2 more specific entries under this disorder, not on this entry itself:
A well-studied disease is usually split into subtypes, and the gene is curated on whichever one the evidence belongs to. Open a subtype to see which gene goes with it.
ICD-10 codes
ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.
Related health topics
Reached through the ICD-10 categories this disease is filed under, so these describe the broader group rather than this disease specifically.
Cross-references
Orphadata Science: Free access data from Orphanet. © INSERM 1999. Data version 2026-06-23. Available under CC BY 4.0. This is a reference, not medical advice.
Powered by Eleplan
A rare diagnosis is just the start. Eleplan keeps the whole care plan in one place.
Diagnoses, medications, documents, appointments, and the whole care team — organized and always in sync, so you are not retelling the same story to every new specialist. With Ellie, your AI care assistant, on top of it. Free to start.