Is Crouzon Syndrome Inherited?
Yes, Crouzon syndrome is inherited in an autosomal dominant pattern, but approximately 50% or more of cases arise from de novo (new) mutations rather than being passed down from parents. 1, 2, 3, 4, 5, 6
Inheritance Pattern
Crouzon syndrome follows autosomal dominant inheritance, meaning:
- If a parent has Crouzon syndrome: There is a 50% chance with each pregnancy of passing the mutation to their child 2, 4, 5
- The causative gene: Mutations occur primarily in the FGFR2 gene (fibroblast growth factor receptor 2), and less commonly in the FGFR3 gene (specifically in Crouzon syndrome with acanthosis nigricans) 5, 6
De Novo Mutations Are Common
A critical clinical point: Many cases—potentially the majority—result from spontaneous new mutations rather than inheritance from an affected parent:
- De novo mutations in FGFR2 are frequently reported 1, 3
- This means parents with no family history can have a child with Crouzon syndrome
- The case of a fraternal twin where only one twin was affected demonstrates this de novo mutation pattern 3
Genetic Counseling Implications
For affected individuals planning families:
- Preimplantation genetic testing for monogenic diseases (PGT-M) is available and effective for preventing transmission 2
- Molecular genetic testing should be performed to confirm the specific mutation
- Next-generation sequencing (NGS) is the preferred diagnostic method for identifying FGFR2 mutations 1
For parents of an affected child with no family history:
- Recurrence risk in future pregnancies is generally low (near population baseline)
- However, germline mosaicism in a parent cannot be completely ruled out
- Genetic counseling and testing of parents is recommended to assess recurrence risk
Important Clinical Caveat
Mosaicism can complicate inheritance patterns: One case report described a father with a milder, mosaic form of Crouzon syndrome whose son had the full syndrome 2. When mosaicism involves germ cells, transmission risk exists even when the parent appears mildly or unaffected. This underscores the importance of:
- Genetic testing of apparently unaffected parents when a child is diagnosed
- Recognition that phenotypic severity can vary significantly within families
- Understanding that mosaic carriers may have subtle or no clinical manifestations