Causes and diagnosis of Apert syndrome
Apert syndrome is caused by a mutation in the FGFR2 gene (10q25.3-10q26) involved in cell signaling during embryonic development. Advanced paternal age has been associated with de novo mutations, which are found in most cases.
Diagnosis is based on the clinical findings at birth. Some cases may be identified prenatally and if suspected during pregnancy, a diagnosis can be confirmed by molecular genetic testing.
Apert syndrome follows an autosomal dominant pattern of inheritance. The recurrence risk for unaffected parents of affected children is low, but the risk to affected patient's offspring is 50%. Genetic counseling should be provided to affected families.
How is Apert syndrome diagnosed? Is genetic testing always needed to confirm the diagnosis?
Apert syndrome and the other conditions associated with FGFR-related craniosynostosis were clinically defined long before the molecular basis of this group of disorders was discovered. Apert syndrome can be diagnosed primarily based on the following clinical findings:
- Turribrachycephalic skull shape (cone-shaped or towering skull) which is observable clinically and can be confirmed by skull radiograph or head CT examination;
- Characteristic facial features including moderate-to-severe underdevelopment of the midface, bulging and wide-set eyes, beaked nose, underdeveloped jaw and shallow eye sockets;
- Variable hand and foot findings such assyndactyly of the fingers and toes and polydactyly.
While clinical findings are suggestive of Apert syndrome, molecular genetic testing can help to confirm the diagnosis. Fibroblast growth factor receptor type 2 (FGFR2) sequence analysis is highly sensitive for Apert syndrome. More than 98% of cases are caused by a specific mutation in the 7th exon of the gene encodingFGFR2. The remaining cases are due to another specific mutation in or near exon 9 of FGFR2.
GeneTests lists laboratories offering clinical genetic testing for this condition. Clinical genetic tests are ordered to help diagnose a person or family and to aid in decisions regarding medical care or reproductive issues. Talk to your health care provider or a genetic professional to learn more about your testing options.
Other Names for this Disease
- Acrocephalo-syndactyly type 1
- ACS 1
- Apert-Crouzon disease
- Syndactylic oxycephaly