This mechanism was present in ACH children carrying the G380R mutation but also in a patient in whom no mutation could be detected in the entire coding region of the FGFR3 gene.
A 2-year-old boy with clinical features consistent with achondroplasia and Silver-Russell syndrome-like symptoms was found to carry a mutation in the fibroblast growth factor receptor-3 (FGFR3) gene at c.1138G > A (p.Gly380Arg) and a de novo 574 kb duplication at chromosome 7p12.1 that involved the entire growth-factor receptor bound protein 10 (GRB10) gene.
An exclusive paternal origin of mutations, and increased paternal age, were previously described for a different mutation (c.1138G>A) of the FGFR3 gene causing achondroplasia, as well as for mutations of the related FGFR2 gene causing Apert, Crouzon and Pfeiffer syndromes.
Within the past year, the achondroplasia locus has been mapped to 4p 16.3 (refs 5-7) and mutations in the fibroblast growth factor receptor 3 (FGFR3) gene have been identified in patients with the disorder.
The mother has achondroplasia and carries the common G1138 (G380R) mutation in the FGFR3 gene; the father has hypochondroplasia due to the C1620A (N540K) mutation in the same gene.
Adjusting for confounders, we found major associations between age and the frequencies of sperm with DFI and fibroblast growth factor receptor 3 gene (FGFR3) mutations associated with achondroplasia (P < 0.01) with no evidence for age thresholds.
Moreover, we show that low dose of NVP-BGJ398 improves in vivo condyle growth and corrects dysmorphologies in Fgfr3<sup>Y367C/+</sup> mice, suggesting that postnatal treatment with NVP-BGJ398 mice might offer a new therapeutic strategy to improve mandible anomalies in ACH and others FGFR3-related disorders.
The vast majority of patients with achondroplasia have a G-to-A transition at position 1138 of the fibroblast growth factor receptor 3 (FGFR3) cDNA sequence, resulting in the Gly-to-Arg substitution at position 380 of the FGFR3 protein.
The phenotype of heterozygous biallelic mutations in FGFR3 associated with ACH is variable, underscoring the importance of recognition and accurate diagnosis to ensure appropriate management.
Fibroblast growth factor receptor 3 (FGFR3) is a key regulator of skeletal growth and activating mutations in Fgfr3 cause achondroplasia, the most common genetic form of dwarfism in humans.
TDI-FGFR3 was not highly phosphorylated under ligand-free conditions, but the peak phosphorylation levels of TDI-FGFR3 and ACH-FGFR3 were maintained for 30 min after stimulation with FGF-1.
These results together with our earlier observation that achondroplasia results from constitutive activation of the related receptor FGFR3, leads to the prediction that other malformation syndromes attributed to FGFRs, such as Pfeiffer syndrome and Thanatophoric dysplasia, also arise from constitutive receptor activation.
Activating mutations of the FGFR3 gene lead to craniosynostosis and multiple types of skeletal dysplasia with varying degrees of severity: thanatophoric dysplasia (TD), achondroplasia and hypochondroplasia.
Using our established techniques for single-cell ratiometric real-time calcium image analysis, we defined the nature of the basic fibroblast growth factor (bFGF)-induced calcium signal in human diploid fibroblasts, and, in blinded studies, have analyzed the bFGF-induced signals from 18 independent fibroblast cell lines, including multiple lines from patients with known mutant alleles of FGFR3 and syndromes of Ach or TD.