Shapiro , et al. - Aim of this work was to distinguish the underlying genetic diagnoses in a paediatric cohort with GH or IGF-1 insensitivity using candidate gene (CGS) and whole exome sequencing (WES) and evaluate factors correlated with the discovery of a genetic defect. Importantly, comprehensive genetic testing validates the genetic heterogeneity of GH/IGF-1 insensitivity and successfully distinguished the genetic aetiology in a significant proportion of cases. The data demonstrated that WES is rapid and may isolate genetic variants that have been missed by traditional clinically driven genetic testing. This emphasises the benefits of specialist diagnostic centres.