Beare-Stevenson syndrome: two new patients, including a novel finding of tracheal cartilaginous sleeve.

Beare-Stevenson syndrome (BSS) is a rare FGFR2-associated craniosynostosis syndrome with a higher rate of sudden unexplained death than related conditions such as Apert, Pfeiffer, and Crouzon syndromes. BSS presents with craniosynostosis, cutis gyrata, and significant developmental delay in most patients who survive infancy. There have only been 21 reported patients with BSS, which limits prognostication for clinicians and likely does not capture the full extent of the phenotype. Here we report on two additional patients with molecularly confirmed BSS, one each with p.Ser372Tyr and p.Tyr375Cys mutations in FGFR2. Cloverleaf skull was identified prenatally in one patient, with initial concern for Crouzon syndrome. Prenatal 3D ultrasound was performed, but cutis gyrata was only visible on retrospective examination following the clinical diagnosis of BSS after birth. Due to phenotypic overlap with Crouzon syndrome, but worse prognosis, we recommend consideration of prenatal 3D ultrasound and mutation testing for patients with suspected Crouzon to allow for prenatal diagnosis of BSS and to enable appropriate genetic counseling and postnatal care. One of our patients was noted to have a tracheal cartilaginous sleeve, which if present could explain sudden death. 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. Tracheal cartilaginous sleeves are often only found incidentally at autopsy as they are difficult to diagnose without direct visualization of the trachea. This association and our experience suggests that BSS patients be evaluated for tracheal cartilaginous sleeve to prevent airway compromise.