Homozygous variants in two unrelated patients with craniosynostosis and radioulnar synostosis.

Background: encodes an intracellular inhibitor of the bone morphogenetic protein (BMP) signalling pathway. Until now, rare heterozygous loss-of-function variants in were demonstrated to increase the risk of disparate clinical disorders including cardiovascular disease, craniosynostosis and radioulnar synostosis. Only two unrelated patients harbouring biallelic variants presenting a complex cardiovascular phenotype and facial dysmorphism have been described.