The normal skull consists of several plates of bone that are separated by sutures. The sutures (fibrous joints) are found between the bony plates in the head. As the infant grows and develops, the sutures close, forming a solid piece of bone, called the skull.
Craniosynostosis is a condition in which the sutures close too early, causing problems with normal brain and skull growth. Premature closure of the sutures may also cause the pressure inside of the head to increase and the skull or facial bones to change from a normal, symmetrical appearance.
What causes craniosynostosis?
Craniosynostosis occurs in one out of 2,200 live births and affects males slightly more often than females.
Craniosynostosis is most often sporadic (occurs by chance). In some families, craniosynostosis is inherited in one of two ways:
- Autosomal Recessive
Autosomal recessive means that two copies of the gene are necessary to express the condition, one inherited from each parent, who are obligate carriers. Carrier parents have a one in four, or 25 percent, chance with each pregnancy, to have a child with craniosynostosis. Males and females are equally affected.
- Autosomal Dominant
Autosomal dominant means that one gene is necessary to express the condition, and the gene is passed from parent to child with a 50/50 risk for each pregnancy. Males and females are equally affected.
Craniosynostosis is a feature of many different genetic syndromes that have a variety of inheritance patterns and chances for reoccurrence, depending on the specific syndrome present. It is important for the child as well as family members to be examined carefully for signs of a syndromic cause (inherited genetic disorder) of craniosynostosis such as limb defects, ear abnormalities, or cardiovascular malformations.