General description of Koolen De Vries Syndrome

Koolen De Vries syndrome, the scientific name of which is Microdélétion 17q21.31, is a rare genetic disorder .

Genetic disease means disease caused by an abnormality in the behavior of a gene.

Rare means that the number of people affected is limited compared to the general population.

Microdeletion 17q21.31 is therefore a genetic state in which a tiny fragment is missing from one of the 46 chromosomes, there is a lack of a small amount of genetic material.

A small number of people with Koolen De Vries syndrome do not have a chromosome 17 microdeletion but a mutation in the KANSL1 * gene which results in a copy of the gene that does not work.

* Translation of the definition of the KANSL 1 gene from the site: The KANSL1 gene provides instructions for creating an element (subunit) of a group of interacting proteins called the NSL regulatory complex KAT8. This complex is classified as a histone acetyltransferase (HAT) complex. It helps regulate gene activity (expression) by modifying chromatin, the DNA and protein complex that conditions DNA in chromosomes.
The protein produced from the KANSL1 gene is found in most organs and tissues in the body before birth and throughout life. Due to its involvement in controlling the activity of other genes, this protein plays an important role in the development and functioning of many parts of the body.

* Traduction de la définition du gêne KANSL 1 issue du site : Le gène KANSL1 fournit des instructions pour la création d'un élément (sous-unité) d'un groupe de protéines en interaction appelé complexe NSL régulateur KAT8. Ce complexe est classé en tant que complexe histone acétyltransférase (HAT). Il aide à réguler l'activité des gènes (expression) en modifiant la chromatine, le complexe d'ADN et de protéines qui conditionne l'ADN dans les chromosomes.La protéine produite à partir du gène KANSL1 se trouve dans la plupart des organes et des tissus du corps avant la naissance et tout au long de la vie. De par son implication dans le contrôle de l'activité d'autres gènes, cette protéine joue un rôle important dans le développement et le fonctionnement de nombreuses parties du corps.

What is a Kool Kid?


Since the syndrome has only been described recently, most of the known people with this syndrome are still children or adolescents.

In connection with the name of the syndrome (see history below), these children are called Kool Kids in the community of parents of children with the syndrome.

It is also true that the vast majority of people with the syndrome are calm or dilettante.

The children and teenagers above are carriers of the syndrome of 3 different families, however don't they have an air of resemblance?

History of the syndrome


If many children are already known to genetic services, it is necessary to wait for technical progress in research and the year 2006 to be able to diagnose the syndrome under the name of the defective gene, 17q21.31 .

Today, everyone who contacts a genetic service can be diagnosed.

We even know children diagnosed in utero in the United States.

The Dutch professors Koolen and De Vries became interested in the syndrome very early on, they discovered it and are still continuing their research work. Very involved, they meet families from all over the world and take part in numerous seminars organized by these same families. (request in progress for photo agreement)

They created a database called Syndrome Monitor and, at the end of 2015, an international database, Genida , was launched. This new database is managed in France by Professors Mandel and Colin . It lists all the symptoms associated with the syndrome and at all ages. This allows us to communicate on the progress of our children and the possible risks to alert doctors and families about the checks to be carried out systematically.

In parallel, thanks to the Internet, parents communicate. The first site is English and managed by a mother. It quickly brings together a few families from all over the world.

With the success of Facebook and more and more diagnoses, a Facebook page is created. In 2015, a first French page dedicated to families was opened, with the collective choice of accepting only parents or brothers and sisters living with a child Koolen de Vries: Koolen de Vries France - microdeletion syndrome17q21.31 . Its access is restricted and is obtained after request to the administrators. To create a dynamic of mutual aid between carers, also isolated, a Facebook page Association Koolen De Vries France the pros corner is opened in May 2018; it is aimed at parents and the medical community for an exchange of practices.

Today, families are grouped mainly by country by opening new pages. This makes it possible to keep each other informed according to each culture and the policies pursued, aid can be very disparate from one country to another.

In 2012, 17q21.31 syndrome was renamed Koolen De Vries Syndrome . Parents from all countries are delighted for two reasons:

  • recognition for these two teachers,

  • a name which corresponds well to our children in view of their character.

We can say that the Kool Kids family was born on this date.

In 2014, the American indie pop group, Echosmith released a song called "Cool Kids". This song quickly becomes an anthem within the parents' community which is only growing.

In 2018, some parents braved their geographic distances and created the association Koolen De Vries France of which this website and the Facebook page Koolen De Vries France - KDVF are the windows.

Most frequent features of the syndrome

(Based on the micro-deletion guide 17q21.31, Unique English association, translation of Valentin APAC association)


Newborns are very hypotonic.

Almost all babies have low muscle tone (hypotonia), their muscle and dermal tissues are too "elastic". This has many consequences on the evolution of their motor development:

  • more difficult sucking, sluggishness for feeding. Some may need a feeding tube. At birth, they may be unable to grip themselves and they suck so weakly that they cannot meet their own dietary needs. Breast milk drawn and an enriched energy formula can be given by a nasogastric tube introduced through the nose until they are strong and mature enough to feed directly from the breast or bottle. False roads are also noticed in some children. Chewing food is difficult, which requires vigilance depending on the meals served.

Example of Kool kid with laryngomalacia: laryngeal malformation causing a stridor. Lots of noise for not much. The stridor is stronger during suction but also present during deep breaths. It subsided and then disappeared over time.

  • tongue often pushed forward or even extended. Some also have a tongue that is too thick and does not find its place in the oral cavity, a symptom called macroglossia. This can sometimes require surgery (two specialists in France for this type of surgery).

  • difficulty speaking or speaking clearly. Rare are the children who produce distinct words before 2 years and it is sometimes necessary to wait until 6 years (very rare adolescents or adults do not speak at all). Communication takes place a lot through gestures, facial expressions or vocal noises. Each parent learns to recognize their child's language. A few are learning limited sign language. Children have trouble reproducing all of the sounds of language. They have difficulty organizing and doing facial movements. This is called verbal dyspraxia (one can also say buccofacial, or oral or oro-facial or oro-bucco-facial). It is a marked feature of the syndrome. At the same time as the strengthening of the tissues, this dyspraxia diminishes and language develops.

Discussion between a 7 and a half year old Kool Kid and Santa Claus

  • holding the head, sitting position, standing and acquisition of delayed walking. Generally, control of bodily movements (fine and gross motor skills) develops slowly and later than in children without chromosomal abnormality. Some children walk before 2 years old, others not before 4 or 5 years old. Muscle tone improves with age but this weak tone can persist and cause other consequences, such as a deviation of the spine. Early intervention by the physiotherapist, occupational therapy or other approaches such as balneotherapy are important. Exercises to tone up are essential. Some children may need suitable seats, walking aids, special shoes or an outdoor wheelchair.

10 months,

I still tumble

18 months,

i don't walk

but can move

23 months,

I'm almost there

but it's faster in youpala

25 months,

That's it !

I walk

4 years and 4 months,

the rope ladder holds no secrets for me

4 years and 8 months,

difficult cycling, even with small wheels. I have little strength in my legs.

5 years and 9 months,

I start in tree climbing

Examples of corsets

EEG, impressive with all these connections but completely painless.

  • We note that children evolve differently, nevertheless certain controls are strongly recommended so as not to miss essential care:

- assessment of general development (for example a doctor in rehabilitation and adaptation, especially for problems


- phoniatric assessment (swallowing)

- speech therapy assessment (language)

- audiological assessment

- kidney ultrasound

- heart evaluation

- MRI of the brain

- EEG in case of suspected epilepsy

- evaluation of a lack of growth hormones in case of small size

- ophthalmic assessment

- dermatological vigilance (often numerous moles)

  • In terms of education, the courses are also very varied and depend on the level of mental handicap, the majority of children are educated with an AESH during the kindergarten period. Some continue in primary school but the majority then integrate specialized courses, ULIS, IME. Many learn to read, some manage to write with a pencil, but problems with fine psychomotricity are often a real obstacle. The keyboard is then a nice alternative. There is almost for everyone an absence of math bump. It is a difficult concept to integrate. If they can memorize lists of operations such as addition tables, then they do not know how to use them and do not see the purpose. In immersion, they are able to learn several languages ​​(parents of different origins or expatriation).

  • In terms of behavior, our children are generally very sociable, friendly, affectionate, empathetic and cooperative, reckless. Which can also be difficult to manage as they grow up because they find it difficult to discern good from bad and could follow anyone who is a little sympathetic at first. They like to laugh and make a lot of jokes. They are children who are open to others and not at all withdrawn.

Laughing, joking eyes

and malicious ....

a big smile...


far from creating melancholy.

  • Our children are very much alike, we are talking about the "kool kids" family. In general, they have a pear-shaped nose, a bulging forehead, wide-set eyes, somewhat large ears, thin lips and an elongated face. They often have light hair and eyes. Do not try to represent them with these scary descriptions, go see the photo at the top of the page instead. You will see that indeed, they are very similar but they are also very beautiful.

Scientific view of the Radbound University Medical Center

University medical center where Doctors Koolen and de Vries officiate


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