Cornelia de Lange syndrome is genetic condition that is caused by mutations in at least five genes (NIPBL, RAD21, SMC3, HDAC8, and SMC1A). The severity of the condition can vary greatly depending on the type of mutation and which gene is affected. More than half of people with CdLS have mutations in the NIPBL gene. This is also associated with more severe disease.
Cornelia de Lange syndrome is rarely inherited. Rather, it usually happens sporadically, with no family history of the disease. This happens because of de novo, or new, mutations.
The HDAC8 and SMC1A genes are found on one of the sex chromosomes, specifically the X chromosome. Only one copy of the mutated gene is necessary to cause the disorder, and it affects both females and males. This differs from many other X-linked disorders, where males are mostly affected. The NIPBL, RAD21, and SMC3 genes are found on autosomes, or the non-sex chromosomes, and only one copy of the mutated gene is necessary to cause the disorder.
The five genes associated with CdLS produce proteins that are involved with development before birth. Specifically, the proteins are responsible for guiding the development of the face, limbs, and other parts the body.