Molecular analysis of her fibroblast growth factor receptor 1 gene (FGFR1) identified a heterozygous P252R missense mutation, previously only reported with FGFR1-Pfeiffer syndrome like manifestations.
These studies provide direct genetic evidence that the Pro252Arg mutation in FGFR1 causes human Pfeiffer syndrome and uncovers a molecular mechanism in which Fgf/Fgfr1 signals regulate intramembraneous bone formation by modulating Cbfa1 expression.
In this paper the expression of FGFR1, the IgIIIa/c and IgIIIa/b isoforms of FGFR2, and FGFR3 is investigated in Apert syndrome (P253R mutation)- and Pfeiffer syndrome (C278F mutation)-affected fetal cranial tissue and is contrasted with healthy human control tissues.
However, unlike the Apert syndrome Pro253Arg FGFR2c mutant, neither the Pfeiffer syndromePro250Arg FGFR1c mutant nor the Muenke syndrome Pro250Arg FGFR3c mutant bound appreciably to FGF7 or FGF10.
Targeted resequencing of FGFR1 in multiple tissues from an independent cohort of individuals with ECCL identified one additional individual with a c.1638C>A (p.Asn546Lys) mutation in FGFR1.
Targeted sequencing of tissue from the right gluteal mass, revealed a mosaic activating FGFR1 c.1966A>G (p.Lys656Glu) mutation, absent in normal left gluteal tissue, confirming the diagnosis of encephalocraniocutaneous lipomatosis (ECCL), belonging to the family of RASopathies (including neurofibromatosis type I, Noonan syndrome, Costello syndrome), with constitutive activation of the mitogen-activated protein kinase (MAPK) pathway, and an increased risk of developing neoplasms.
The associated of FGFR3 mutations with craniosynostosis has been restricted to three mutations, the common p.Pro250Arg in Muenke syndrome, p.Ala391Glu in Crouzon syndrome with acanthosis nigricans, and p.Pro250Leu identified in a family with isolated craniosynostosis.
However, unlike the Apert syndrome Pro253Arg FGFR2c mutant, neither the Pfeiffer syndrome Pro250Arg FGFR1c mutant nor the Muenke syndromePro250Arg FGFR3c mutant bound appreciably to FGF7 or FGF10.
We also identified an FGFR2 p.Ser252Leu mutation in a phenotypically normal father of a daughter with CS, and an FGFR3 p.Pro250Arg mutation in a mildly macrocephalic father of sisters with MS.
Our results confirm a strong correspondence between genotype and facial phenotype for AS and MS with severity of facial dysmorphology diminishing from Apert FGFR2(S252W) to Apert FGFR2(P253R) to MS. We show that AS facial shape variation is increased relative to CS, although CS has been shown to be caused by numerous distinct mutations within FGFRs and reduced dosage in ERF.
The crystal structure, of Pro252Arg FGFR1c in complex with FGF2, demonstrates that the enhanced ligand binding is due to an additional set of receptor-ligand hydrogen bonds, similar to those gain-of-function interactions that occur in the Apert syndromePro253Arg FGFR2c-FGF2 crystal structure.
Somatic activating FGFR1 mutations (p.N546K or p.K656E) were observed in the tumor samples and further evidence for functional relevance was obtained by in silico modeling.
Notably, the patient with an FGFR1 K656E mutated RGNT had undergone a resection of a diencephalic pilocytic astrocytoma with pilomyxoid features 5 years before the discovery of the fourth ventricle tumor; the mutational analysis uncovered the presence of the same FGFR1 K656E mutation in the diencephalic tumor.
Targeted sequencing of tissue from the right gluteal mass, revealed a mosaic activating FGFR1 c.1966A>G (p.Lys656Glu) mutation, absent in normal left gluteal tissue, confirming the diagnosis of encephalocraniocutaneous lipomatosis (ECCL), belonging to the family of RASopathies (including neurofibromatosis type I, Noonan syndrome, Costello syndrome), with constitutive activation of the mitogen-activated protein kinase (MAPK) pathway, and an increased risk of developing neoplasms.
A further test of this hypothesis is provided by a unique family segregating two FGFR2 mutations in cis (S252L; A315S), in which severe syndactyly occurs in the absence of the craniosynostosis that typically accompanies FGFR2 mutations.
Pfeiffer syndrome is a classic form of craniosynostosis that is caused by a proline-->arginine substitution at amino acid 252 (Pro252Arg) in fibroblast growth factor receptor 1 (FGFR1).
A further test of this hypothesis is provided by a unique family segregating two FGFR2 mutations in cis (S252L; A315S), in which severe syndactyly occurs in the absence of the craniosynostosis that typically accompanies FGFR2 mutations.
An oncogenic fibroblast growth factor receptor 1 (FGFR1) mutation (N546K) was detected, and the FGFR1 locus frequently showed copy number gain (31.7%) in primary tumors.