Of note, tracheal cartilaginous sleeves have been reported in other FGFR2-related craniosynostosis syndromes, and are associated with 90% risk of death by two years of age without tracheostomy.
Apert syndrome is an autosomal dominant disease characterized by craniosynostosis and bony syndactyly associated with point mutations (S252W and P253R) in the fibroblast growth factor receptor (FGFR) 2 that cause FGFR2 activation.
Syndactyly has not been previously described in TD or other conditions with FGFR3 mutations, but occurs in several craniosynostosis syndromes due to mutations in FGFR2.
Mutations in the fibroblast growth factor receptor 2 (FGFR2) gene have been identified in Crouzon syndrome, an autosomal dominant condition causing premature fusion of the cranial sutures (craniosynostosis).
Besides the cranial phenotype, brain dysmorphologies are present and are not seen in other FGFR2-asociated craniosynostosis, such as Crouzon syndrome (CS).
Recently, mutations of the fibroblast growth factor receptor 2 (FGFR2) gene have been associated with several craniosynostosis conditions including Apert, Crouzon, Jackson-Weiss, and Pfeiffer syndromes.
We provide linkage evidence using intragenic and flanking microsatellite markers suggesting that the disease in this family was not caused by a mutation in one of the known craniosynostosis loci (FGFR1, FGFR2, FGFR3, MSX2, TWIST).
Since FGF8 maps to the same chromosomal region as FGFR2, has indeed been shown to be a ligand for FGFR2, and has an expression pattern consistent with limb and craniofacial anomalies, we have screened two kindreds with Pfeiffer syndrome that were previously linked to markers from 10q24-25 and a large number of individuals with craniosynostosis and limb anomalies for mutations in the coding sequence of FGF8.
A 20-gene panel was designed based on the genes' association with craniosynostosis, and clinically validated through retrospective testing of an Australian and New Zealand cohort of 233 individuals with craniosynostosis in whom previous testing had not identified a causative variant within FGFR1-3 hot-spot regions or the TWIST1 gene.
Unregulated fibroblast growth factor 2 (FGF2) signaling caused by mutations in the fibroblast growth factor receptor (FGFR2) leads to human craniosynostosis such as the Apert syndrome.
A mutation in FGFR1 has been established in several families with Pfeiffer syndrome, where craniosynostosis is associated with specific digital abnormalities.