Conclusion
This is the first report of complete loss of Spry-1 function in humans, associated with abnormalities of the cranial sutures, inner ear, and kidneys.
Methods
Analysis of whole-genome sequencing data from individuals with craniosynostosis enrolled in the 100,000 Genomes Project identified a likely pathogenic variant within SPRY1. Reverse-transcriptase PCR and western blot analysis were used to investigate the effect of the variant on SPRY1 mRNA and protein, in lymphoblastoid cell lines from the patient and both parents.
Results
A nonsense variant in SPRY1, encoding p.(Leu27*), was confirmed to be heterozygous in the unaffected parents and homozygous in the child. The child's phenotype, which included sagittal craniosynostosis, subcutaneous cystic lesions overlying the lambdoid sutures, hearing loss associated with bilateral cochlear and vestibular dysplasia and a unilateral renal cyst, overlapped the features reported in Spry1-/- null mice. Functional studies supported escape from nonsense-mediated decay, but western blot analysis demonstrated complete absence of full-length protein in the affected child and a marked reduction in both parents.