We describe the first bona fide case of a patient with craniosynostosis (the premature fusion of the gaps in our skull plates known as sutures) and a homozygous variant in SPRY1. The variant results in complete loss of the protein in the child, and reduced levels of the protein in both heterozygous parents. The child displays a distinctive phenotype of fusion of the sagittal suture (midline of the skull), cystic lesions overlying the lambdoid sutures, and hearing anomalies. The clinical features overlap those reported in animal models, but with differences in relative severity; for example, kidney anomalies are a predominant feature of loss of Spry1 in mice, yet our patient displays a mild kidney anomaly. Additional human cases would be required to confirm consistent phenotypic features. The analysis of 617 individuals without a genetic cause to their craniosynostosis did not identify further cases. (By Rebecca Tooze, https://jmg.bmj.com/content/early/2022/12/21/jmg-2022-108946 )