The FGFR2 gene, encoding the FGFR2 protein, plays a crucial role in embryonic cell development, particularly in bone tissue. Bent Bone Dysplasia (BBD), FGFR2-related (MIM# 614592), is a rare severe skeletal dysplasia characterized by craniofacial differences, reduced bone mineral density, and bowed long bones. Only 14 individuals have been reported, of which the majority died prenatally or neonatally. We report the clinical trajectory of a 4-year-old male with BBD, FGFR2-related (FGFR2, c.1141T>G), who initially presented neonatally with respiratory insufficiency requiring intubation, facial dysmorphism, and skeletal differences. He is able to walk, is interactive, has a tracheostomy for mechanical ventilation at night and a gastrostomy tube, and continues to make steady developmental progress. He is currently the longest reported living individual and with BBD, FGFR2-related in the literature to date. Our findings suggest that BBD, FGFR2-related is not definitively lethal perinatally. While the risk for complications and early postnatal death remains high, as demonstrated in previous literature, survival beyond the early postnatal period is possible. This report broadens the known postnatal developmental and medical trajectory of BBD, FGFR2-related, which is crucial for providing comprehensive genetic counseling.

Craniosynostosis results from the premature fusion of cranial sutures, with an incidence of 1 in 2,100-2,500 live births. The majority of cases are non-syndromic and involve single suture fusion, whereas syndromic cases often involve complex multiple suture fusion. The fibroblast growth factor receptor 2 (FGFR2) gene is perhaps the most extensively studied gene that is mutated in various craniosynostotic syndromes including Crouzon, Apert, Pfeiffer, Antley-Bixler, Beare-Stevenson cutis gyrata, Jackson-Weiss, Bent Bone Dysplasia, and Seathre-Chotzen-like syndromes. The majority of these mutations are missense mutations that result in constitutive activation of the receptor and downstream molecular pathways. Treatment involves a multidisciplinary approach with ultimate surgical fixation of the cranial deformity to prevent further sequelae. Understanding the molecular mechanisms has allowed for the investigation of different therapeutic agents that can potentially be used to prevent the disorders. Further research efforts are need to better understand screening and effective methods of early intervention and prevention. Herein, the authors provide a comprehensive update on FGFR2-related syndromic craniosynostosis.