fied by WES followed by nine additional patients by Sanger sequencing, ranging in severity from Walker Warburg syndrome to limb girdle muscular dystrophy; (ii) two genes are responsible for a congenital form of spinal muscular atrophy affecting the lower limbs (three cases mutated for one gene and two cases for a second gene); (iii) one gene is responsible for a core myopathy/King Demborough phenotype in a large consanguineous family.Conclusions: New generation sequencing allows the identification of novel genes much more effectively than previous techniques. The level of genetic heterogeneity of neuromuscular disorders exceeds recent estimations and it is realistic to expect that we will at least double the number of genes involved in neuromuscular conditions in the next few years.This brings significant challenges; firstly the necessity to clearly define the phenotype of patients; secondly the need to be involved in collaborative studies to access other patients affected by these often exceedingly rare conditions; finally the demonstration of pathogeneicity of putative mutations in novel genes.These challenges can be addressed by deep phenotyping, access to international collaboration networks and biobanked material, and multidisciplinary collaborations.Acknowledgements: The Wellcome Trust Sanger Institute; affected families; the Muscular Dystrophy Campaign; the GOSH Charity; and colleagues from the Dubowitz neuromuscular centre; the DNA laboratory at Guy's Hospital.