Diagnostic value of exome and whole genome sequencing in craniosynostosis.

Abstract

Craniosynostosis, the premature fusion of one or more cranial sutures, occurs in ∼1 in 2250 births, either in isolation or as part of a syndrome. Mutations in at least 57 genes have been associated with craniosynostosis, but only a minority of these are included in routine laboratory genetic testing. We used exome or whole genome sequencing to seek a genetic cause in a cohort of 40 subjects with craniosynostosis, selected by clinical or molecular geneticists as being high-priority cases, and in whom prior clinically driven genetic testing had been negative. We identified likely associated mutations in 15 patients (37.5%), involving 14 different genes. All genes were mutated in single families, except for <i>IL11RA</i> (two families). We classified the other positive diagnoses as follows: commonly mutated craniosynostosis genes with atypical presentation (<i>EFNB1</i>, <i>TWIST1</i>); other core craniosynostosis genes (<i>CDC45</i>, <i>MSX2, ZIC1</i>); genes for which mutations are only rarely associated with craniosynostosis (<i>FBN1</i>, <i>HUWE1</i>, <i>KRAS</i>, <i>STAT3</i>); and known disease genes for which a causal relationship with craniosynostosis is currently unknown (<i>AHDC1</i>, <i>NTRK2</i>). In two further families, likely novel disease genes are currently undergoing functional validation. In 5 of the 15 positive cases, the (previously unanticipated) molecular diagnosis had immediate, actionable consequences for either genetic or medical management (mutations in <i>EFNB1</i>, <i>FBN1</i>, <i>KRAS</i>, <i>NTRK2, STAT3</i>). This substantial genetic heterogeneity, and the multiple actionable mutations identified, emphasises the benefits of exome/whole genome sequencing to identify causal mutations in craniosynostosis cases for which routine clinical testing has yielded negative results.