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Disease Information

Summary

Koolen-de Vries syndrome is a disorder characterized by developmental delay and mild to moderate intellectual disability. People with this disorder typically have a disposition that is described as cheerful, sociable, and cooperative. They usually have weak muscle tone (hypotonia) in childhood. About half have recurrent seizures (epilepsy). Affected individuals often have distinctive facial features including a high, broad forehead; droopy eyelids (ptosis); a narrowing of the eye openings (blepharophimosis); outer corners of the eyes that point upward (upward-slanting palpebral fissures); skin folds covering the inner corner of the eyes (epicanthal folds); a bulbous nose; and prominent ears. Males with Koolen-de Vries syndrome often have undescended testes (cryptorchidism). Defects in the walls between the chambers of the heart (septal defects) or other cardiac abnormalities, kidney problems, and skeletal anomalies such as foot deformities occur in some affected individuals.

About Koolen-de Vries syndrome

Many rare diseases have limited information. Currently, GARD aims to provide the following information for this disease:

  • Symptoms:May start to appear during Pregnancy, at Birth, and as an Infant.
  • Cause:This disease is caused by a change in the genetic material (DNA).
  • Organizations:Patient organizations dedicated to this rare disease are available on GARD, or you may contact a GARD Information Specialist for additional information.
  • Categories:Genetic diseases(Genetic diseases affect the DNA, or genetic instructions, which directs how tissues, organs, and body systems function.)Neurological diseases(Neurological diseases affect the brain, spinal cord, cranial nerves, autonomic nerves, or other peripheral nerves.)Birth defects(Birth defects are structural changes present at birth that can affect almost any part of the body, including how the body looks, works, or both.)

Resource(s) for Medical Professionals and Scientists on This Disease:

  • ClinGen provides expert-reviewed information on genes and gene variants for use in research and medicine.
  • GeneReview provides clinical information on genetic diseases, including diagnosis, treatment, and genetic counseling.
  • MONDO provides GARD with information for this disease.
  • Orphanet provides GARD with information for this disease.
  • RARe-SOURCE™ offers rare disease gene variant annotations and links to rare disease gene literature.

Resource(s) for Medical Professionals and Scientists on This Disease:

  • ClinGen provides expert-reviewed information on genes and gene variants for use in research and medicine.
  • GeneReview provides clinical information on genetic diseases, including diagnosis, treatment, and genetic counseling.
  • MONDO provides GARD with information for this disease.
  • Orphanet provides GARD with information for this disease.
  • RARe-SOURCE™ offers rare disease gene variant annotations and links to rare disease gene literature.

About Koolen-de Vries syndrome

Many rare diseases have limited information. Currently, GARD aims to provide the following information for this disease:

  • Symptoms:May start to appear during Pregnancy, at Birth, and as an Infant.
  • Cause:This disease is caused by a change in the genetic material (DNA).
  • Organizations:Patient organizations dedicated to this rare disease are available on GARD, or you may contact a GARD Information Specialist for additional information.
  • Categories:Genetic diseases(Genetic diseases affect the DNA, or genetic instructions, which directs how tissues, organs, and body systems function.)Neurological diseases(Neurological diseases affect the brain, spinal cord, cranial nerves, autonomic nerves, or other peripheral nerves.)Birth defects(Birth defects are structural changes present at birth that can affect almost any part of the body, including how the body looks, works, or both.)

Causes

What Causes This Disease?

Genetic Mutations

Changes in your genes (also called variants) cause Koolen-de Vries syndrome.

Genes are sections of DNA that contains instructions that help the body grow, develop, and function. A genetic variant is a change in your DNA's order. Parents may pass variants to their children, or they may occur randomly. They may result from viruses, environmental factors, such as UV radiation, or a combination of causes.

Most genetic variants do not cause disease. However, some can affect how a gene works and interfere with the body's normal functions. A pathogenic variant is one that causes disease.

If you think you may have this disease, collect your family health history (CDC). It may help you and your medical team to know about family members who have had the disease or similar symptoms and when those symptoms first appeared.

Read more about genetic disorders (NIH MedlinePlus). 

Genetic Mutations

Changes in your genes (also called variants) cause Koolen-de Vries syndrome.

Genes are sections of DNA that contains instructions that help the body grow, develop, and function. A genetic variant is a change in your DNA's order. Parents may pass variants to their children, or they may occur randomly. They may result from viruses, environmental factors, such as UV radiation, or a combination of causes.

Most genetic variants do not cause disease. However, some can affect how a gene works and interfere with the body's normal functions. A pathogenic variant is one that causes disease.

If you think you may have this disease, collect your family health history (CDC). It may help you and your medical team to know about family members who have had the disease or similar symptoms and when those symptoms first appeared.

Read more about genetic disorders (NIH MedlinePlus). 

Known Genetic Mutations

Koolen-de Vries syndrome is caused by genetic mutations in the following known gene(s):

KANSL1
Learn more about these genes by searching them on the National Library of Medicine (NLM).

Given these known genetic mutation(s), you may want to ask your health care team if genetic testing is right for you. Genetic tests are laboratory tests that use samples of blood, saliva, or other tissues to help identify changes in genes, chromosomes, or proteins. Genetic testing can help confirm or rule out a suspected genetic disease or can provide other useful information to your health care team. Learn more about genetic testing from the National Human Genome Research Institute (NHGRI).

Can diseases be passed down from parent to child?

A biological parent can sometimes pass down genetic changes, called mutations, that cause a disease or increase the chances of developing it. This is called inheritance. Knowing if other family members have had the disease, also known as your family health history, can give your medical team important information. The Surgeon General offers a tool to help you collect your family health history.

Autosomal Dominant

Autosomal means the gene involved is located on one of the numbered chromosomes. Dominant means that a child only needs to inherit one copy of the mutated gene, from either biological parent, to be affected by the disease.

People affected by an autosomal dominant disease have a 50% chance of passing on the mutated gene to their biological child.

Learn more about inheritance patterns from the National Library of Medicine (NLM).

Autosomal Dominant

Autosomal means the gene involved is located on one of the numbered chromosomes. Dominant means that a child only needs to inherit one copy of the mutated gene, from either biological parent, to be affected by the disease.

People affected by an autosomal dominant disease have a 50% chance of passing on the mutated gene to their biological child.

Learn more about inheritance patterns from the National Library of Medicine (NLM).

When Do Symptoms of Koolen-de Vries syndrome Begin?

Symptoms of this disease may start to appear during Pregnancy, at Birth, and as an Infant.

The age symptoms may begin to appear differs between diseases. Symptoms may begin in a single age range, or during several age ranges. The symptoms of some diseases may begin at any age. Knowing when symptoms may have appeared can help medical providers find the correct diagnosis.
  1. Prenatal Selected
    Before Birth
  2. Newborn Selected
    Birth-4 weeks
  3. Infant Selected
    1-23 months
  4. Child
    2-11 years
  5. Adolescent
    12-18 years
  6. Adult
    19-65 years
  7. Older Adult
    65+ years
Symptoms may start to appear during Pregnancy, at Birth, and as an Infant.
This information comes from Orphanet

Symptoms

You may have one or more symptoms, and they may be mild or severe. Having some or all of these symptoms does not mean you have this disease. Only a health care provider can diagnose you.

Common

Many people have these, but not everyone.

  • Abnormal cardiac septum morphology
  • Abnormal dentition (Abnormality of the dentition)
  • Abnormality of hair texture
  • Abnormality of the heart (Abnormal heart morphology)
  • An opening in the wall separating the top two chambers of the heart (Atrial septal defect)
  • Aplasia/Hypoplasia of the corpus callosum
  • Broad forehead
  • Bulbous nose
  • Chiari type I malformation
  • Coarse facial features
  • Cross-eyed (Strabismus)
  • Decreased size of tooth (Microdontia)
  • Delayed speech and language development
  • Disease of the heart muscle (Cardiomyopathy)
  • Double-Jointed (Joint hypermobility)
  • Drooping lower lip (Everted lower lip vermilion)
  • Drooping upper eyelid (Ptosis)
  • Eye folds (Epicanthus)
  • Feeding difficulties in infancy
  • Global developmental delay
  • High forehead
  • High, narrow palate
  • Hip dislocation
  • Hole in heart wall separating two lower heart chambers (Ventricular septal defect)
  • Hypospadias
  • Intellectual disability
  • Intraventricular hemorrhage
  • Long face
  • Long slender fingers (Arachnodactyly)
  • Loss of hair color (Hypopigmentation of hair)
  • Low muscle tone (Hypotonia)
  • Narrow opening between the eyelids (Blepharophimosis)
  • Narrow palate
  • Nasal speech (Hypernasal speech)
  • Optic atrophy
  • Overfolded ears (Overfolded helix)
  • Overfriendliness
  • Poor speech
  • Prominent ear (Protruding ear)
  • Prominent nasal bridge
  • Seizure
  • Severe farsightedness (High hypermetropia)
  • Thick nasal alae
  • Underdeveloped tissue around nostril (Underdeveloped nasal alae)
  • Undescended testes (Cryptorchidism)
  • Upward slanting of the opening between the eyelids (Upslanted palpebral fissure)
  • Ventriculomegaly
  • Wide nasal bridge

Uncommon

Some people have these, but most people do not.

  • Abnormal tooth enamel (Abnormal dental enamel morphology)
  • Abnormally small skull (Microcephaly)
  • Anxiety
  • Aortic valve has two leaflets rather than three (Bicuspid aortic valve)
  • Attention deficit (Attention deficit hyperactivity disorder)
  • Cafe-au-lait spot
  • Cleft palate
  • Clouding of the lens of the eye (Cataract)
  • Conductive deafness (Conductive hearing impairment)
  • Double ureter (Ureteral duplication)
  • Dry skin
  • Extra kidney (Renal duplication)
  • Failure of development of between one and six teeth (Hypodontia)
  • Flat feet (Pes planus)
  • Funnel chest (Pectus excavatum)
  • Hunched back (Kyphosis)
  • Hydronephrosis
  • Ichthyosis
  • Long fingers
  • Numerous moles (Numerous nevi)
  • Pyloric stenosis
  • Recurrent middle ear infection (Recurrent otitis media)
  • Scoliosis
  • Sensorineural hearing impairment
  • Short stature
  • Softening of voice box tissue (Laryngomalacia)
  • Spina bifida
  • Spinal dimple (Sacral dimple)
  • Strawberry mark (Hemangioma)
  • Stuttering
  • Underactive thyroid (Hypothyroidism)
  • Vertebral fusion
  • Vertebral segmentation defect
  • Vesicoureteral reflux
This information comes from the Human Phenotype Ontology (HPO)

Navigating Health Care Decisions

On average, it can take more than six years to receive an accurate diagnosis. Many primary care providers (PCPs) may not be familiar with rare diseases, and patients often need to visit multiple specialists or seek second opinions to get answers.

If a diagnosis remains unclear, visiting a multidisciplinary care center or university hospital may help. These centers bring together teams of specialists who can work together to evaluate symptoms and coordinate a diagnosis. This team-based approach is also helpful after a diagnosis, when managing care for rare diseases.

Because only about 5% of rare diseases have FDA-approved treatments, finding the right healthcare team to manage your symptoms and overall health is essential. People living with rare diseases often face challenges such as delayed diagnosis, limited treatment options, and difficulty accessing knowledgeable providers. Building a care team that understands your needs can make a significant difference in your quality of life.

Your Health Care Team

Why is building the right health care team important?

Building the right health care team is key to the diagnosis, treatment, and management of your long-term health journey living with a rare disease. Start by choosing a primary care provider (PCP). Your PCP will be your main point of contact and help coordinate care with other medical professionals. Your PCP may order tests or refer you to specialists. To find a PCP near you, use the Medicare provider search tool and enter your location and “Primary Care Provider.”

Seeing multiple specialists is important for people with rare diseases because these conditions often affect many parts of the body and require care from doctors with different expertise. Most primary care providers may not be familiar with rare diseases, so involving specialists can lead to a more accurate diagnosis and better care. A coordinated team approach ensures that all symptoms are addressed and that care is well-managed. It can also connect patients with the latest research or treatment options.

A PCP that specializes in the care of children is called a pediatrician. Use this tool by the American Academy of Pediatrics to find a pediatrician in your area by inputting your location.

These specialists may help in the diagnosis, management, and treatment of Koolen-de Vries syndrome:

Orthopedists, also known as orthopedic surgeons, are doctors with specialized training in diagnosing and treating conditions that affect the bones, joints, muscles, tendons, and ligaments. They care for people with arthritis, scoliosis, sports injuries, bone fractures, and rare or inherited bone conditions. Orthopedists may use imaging tests and physical exams to identify the cause of pain, stiffness, or limited movement. Treatment may include physical therapy, medication, or surgery.

You may want to consider bringing a copy of your medical history and a list of any medications to your appointment.

Ask your primary care provider for a referral or use this directory by Medicare to search for an orthopedist specialist in your area. Search using the keyword “Orthopedics.”
Neurologists are doctors with specialized training in diagnosing and treating conditions that affect the brain, spinal cord, and nerves. These parts of the nervous system help control how the body moves, feels, and thinks. Neurologists often care for people with seizures, memory problems, muscle weakness, movement disorders, and inherited conditions such as muscular dystrophies. To better understand a person's symptoms, neurologists may use imaging tests that show the brain or spine, or tests that measure the brain’s electrical activity.

You may want to consider bringing a copy of your medical history and a list of any medications to your appointment.

Ask your primary care provider for a referral or use this directory provided by the American Board of Psychiatry and Neurology to find a specialist. 
Geneticists are doctors trained to diagnose and manage conditions caused by genetic changes, birth defects, or metabolic disorders. Metabolic disorders affect how the body makes or uses energy. Geneticists often work alongside genetic counselors to review family history, discuss genetic risks, explain testing options, and interpret genetic test results. They help people understand how inherited conditions may affect them and their families.

You may want to consider bringing a copy of your medical history and a list of any medications to your appointment.

Ask your primary care provider for a referral or use this directory provided by the American College of Medical Genetics and Genomics to find a specialist.

Multidisciplinary Care Centers

Is It Time to Get a Second Opinion or Specialized Evaluation?

If you've visited your PCP, met with specialists, and undergone the recommended tests, but are still searching for a diagnosis, it may be time to visit an academic medical center or, for pediatric patients, a children's hospital. Academic medical centers and children's hospitals, often called multidisciplinary care centers, typically bring together specialists from different fields to work together on complex cases like rare diseases.

Multidisciplinary care centers may offer more coordinated care and be involved in clinical research, which may help reduce the time to diagnosis and provide access to emerging diagnostic tools. Specialists at these centers may have a deeper understanding of rare diseases and serve as a resource when you'd like a second opinion, particularly when test results or treatment plans are not delivering expected results.

Find hospitals that may partner with medical schools and programs in your area. 

Children’s hospitals and large teaching hospitals may also offer dedicated specialists and programs for pediatric patients with undiagnosed or rare diseases. These programs bring pediatric experts together in one place and may provide more coordinated care for your child.

Search for children's or university hospitals in your area.

Rare Disease Experts

How can you find a rare disease expert?

If a diagnosis, care management, or treatment plan remains unclear despite extensive efforts by your PCP and specialists, it may be time to find a rare disease expert for your disease, if available. A rare disease expert is a medical provider that has knowledge or training on specific rare disease(s), but there may only be a few experts in your state, region, or country. Rare disease experts may work at large research or teaching hospitals, sometimes called centers of excellence. Centers of Excellence commit to sharing knowledge and best practices that can lead to improved care and treatment for individuals living with a rare disease. 

You can also contact a GARD Information Specialist for help finding experts, centers of excellence, or clinics that focus on your disease.
You can ask your care providers for help finding an expert or use directory tools to search for experts near you. The following organization(s) may maintain a list of experts or expert centers for people living with Koolen-de Vries syndrome:

Find Your Community

How can patient organizations help?

Patient organizations can help patients and families connect. They build public awareness of the disease and are a driving force behind research to improve patients' lives. They may offer online and in-person resources to help people live well with their disease. Many collaborate with medical experts and researchers.

Services of patient organizations differ, but may include:

  • Ways to connect to others and share personal stories
  • Easy-to-read information
  • Up-to-date treatment and research information
  • Patient registries
  • Lists of specialists or specialty centers
  • Financial aid and travel resources


Please note: GARD provides organizations for informational purposes only and not as an endorsement of their services. Contact a GARD Information Specialist for more information on organizations that may be dedicated to this disease. Please contact an organization directly if you have questions about the information or resources it provides.


View GARD's criteria for including patient organizations, which can be found under the FAQs on our About GARD page. Request an update or to have your organization added to GARD. 

Patient Organizations

7 Organizations

Koolen-de Vries Syndrome Foundation

People With

Koolen-de Vries syndrome

Helpful Links
Country

United States

Simons Searchlight

People With

Koolen-de Vries syndrome

Helpful Links
Country

United States

Chromosome Disorder Outreach

People With

Koolen-de Vries syndrome

Country

United States

World Craniofacial Foundation

People With

Craniofacial anomalies

Helpful Links
Country

United States

Children's Craniofacial Association

People With

Craniofacial anomalies

Country

United States

FACES: The National Craniofacial Association

People With

Craniofacial anomalies

Country

United States

myFace

People With

Craniofacial anomalies

Country

United States

OrganizationPeople WithHelpful LinksCountry
Koolen-de Vries Syndrome FoundationKoolen-de Vries syndromeResearch RegistryUnited States
Simons SearchlightKoolen-de Vries syndromeResearch RegistryUnited States
Chromosome Disorder OutreachKoolen-de Vries syndromeUnited States
World Craniofacial FoundationCraniofacial anomaliesList of ExpertsUnited States
Children's Craniofacial AssociationCraniofacial anomaliesUnited States
FACES: The National Craniofacial AssociationCraniofacial anomaliesUnited States
myFaceCraniofacial anomaliesUnited States

Participate in Research

Clinical studies are a part of clinical research and play an important role in medical advances for rare diseases. Through clinical studies, researchers may ultimately uncover better ways to treat, prevent, diagnose, and understand human diseases.

What Are Clinical Studies?

Clinical studies are medical research involving people as participants. There are two main types of clinical studies:

  1. Clinical trials determine if a new test or treatment for a disease is effective and safe by comparing groups receiving different tests/treatments.
  2. Observational studies involve recording changes over time among a specific group of people in their natural settings.

Learn more about clinical trials from this National Institutes of Health webpage.

Why Participate in Clinical Studies?

People participate in clinical trials for many reasons. People with a disease may participate to receive the newest possible treatment and additional care from clinical study staff as well as to help others living with the same or a similar disease. Healthy volunteers may participate to help others and to contribute to moving science forward.

To find the right clinical study we recommend you consult your doctors, other trusted medical professionals, and patient organizations. Additionally, you can use ClinicalTrials.gov to search for clinical studies by disease, terms, or location.

What if There Are No Available Clinical Studies?

ResearchMatch helps connect people interested in research studies  with researchers from top medical centers across the United States. Anyone from the U.S. can register with this free program funded by NIH. Researchers from participating institutions use the database to search for and invite patients or healthy volunteers who meet their study criteria to participate.

Why may you want to consider joining the All of Us Research Program?

The All of Us Research Program is inviting 1 million people from all backgrounds across the U.S. to help build one of the most diverse health databases in history. Researchers will use the data to learn how our biology, lifestyle, and environment affect health. This may one day help them find ways to treat and prevent diseases.

ClinicalTrials.gov, an affiliate of NIH, provides current information on clinical research studies in the United States and abroad. Talk to a trusted doctor before choosing to participate in any clinical study. We recommend checking this site often and searching for studies with related terms/synonyms to improve results.
Search ClinicalTrials.gov for this disease.
GARDGenetic and Rare Diseases
Information Center
Contact a GARD Information Specialist if you need help finding more information on this rare disease or available clinical studies. Please note that GARD cannot enroll individuals in clinical studies.
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Sources & References

Last Updated: September 2026