About CdLS?

The Cornelia de Lange syndrome (CdLS) is a rare genetic disorder of which many people have never heard of. Children with CdLS 'look' the same, there is a lot of similarity in appearance and behavior. In 1933, the Dutch pediatrician Cornelia de Lange described in an article in a medical journal two children with a number of strikingly similar characteristics. The syndrome was therefore named after her.

CdLS can affect many parts of the body and individuals with CdLS may display physical, cognitive and behavioural characteristics. Cognitive characteristics are brain-based processes like memory and thinking. Behavioural characteristics refer to certain behaviours that individuals with CdLS are more likely to have. These characteristics can vary widely among affected individuals and range from small differences compared to other people to very noticeable differences. Our International panel of experts have put together a comprehensive guide to the diagnosis and management of CdLS, linked here.


A baby with CdLS is (sometimes a lot) smaller and lighter than average. The child has a striking face with nicely curved and often continuous eyebrows and long eyelashes. Missing fingers or missing larger parts of the arm are easily noticed. The child can also be excessively hairy, especially on the back. In addition, from the beginning  there are often difficulties with sucking and swallowing.

CdLS is congenital, this means that it is already present before birth and that most characteristics can be recognized at birth or shortly afterwards. However, if the characteristics are subtle, the diagnosis can be delayed. In some children the characteristics only become clearer with growing up. We now of people only diagnosed at later age (up to adulthood). Although most children with CdLS are very similar, it is important to remember that a child is also part of the family and will therefore also resemble his father and mother or his brothers and sisters.

The cause of CdLS

Children with CdLS are born anywhere in the world, regardless of race, age of parents, religion or socio-economic status. The syndrome does not follow a predictable pattern, it can 'strike' the oldest, middle or youngest child in the family and it is just as common in boys as in girls. It is estimated that CdLS occurs in 1 in 10,000 to 30,000 newborn children.

We think that there are certainly more who do not yet have a diagnosis. It is the mission of the worldwide CdLS organizations to reach as many people as possible and to provide support to their families.

The cause of CdLS was found in 2004. It is a rare and 'accidental' change in the genetic material of the child. The syndrome is not due to something that was done or neglected during pregnancy.
The cause is called a genetic mutation. The mutations are found in both people with mild and severe disabilities.
The research continues. One hopes to better understand what the changed genes 'do' or do not 'do' and how it is that this syndrome can vary so strongly from person to person. Ultimately, with improved knowledge, it also hopes to improve the quality of life of people with CdLS.

Repeat chance / prenatal examination

Since persons with CdLS will rarely have children themselves, the altered gene is almost never passed on. There are people who have the syndrome in mild degree, who themselves have become a parent of a child with CdLS. There are also several families worldwide with more than one child with CdLS without one of the parents appearing to have the syndrome. Despite these examples, repetition of CdLS within the same family is very rare. Research shows that the maximum repetition probability is less than 1% (approximately 0.6%).

Parents of a child with CdLS who consider family enlargement and have questions about it can be informed by a clinical geneticist. For parents of a child with CdLS who are insecure about a possible next pregnancy, this can help ease their worries.
When a prenatal examination is considered in a subsequent pregnancy, it is important that parents can discuss the benefits and risks with a geneticist who is up to date with the latest information about the possibilities for further research.

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