A heterogeneous genetic disorder is one where the same disease or condition can be caused, or contributed to, by a number of different genes. The traditional strategy for genetic testing involves sequential sequencing of individual genes, selected according to the patient’s clinical presentation and family history. By contrast, next generation sequencing (NGS) involves the sequencing of millions of small fragments of DNA at the same time. Reductions in the cost of NGS now make it a more attractive solution for clinical diagnostic testing to identify the disease-causing mutation(s) in patients with genetically heterogeneous disorders than traditional sequential testing. In particular, the targeted NGS approach which restricts analysis to genes known to be implicated in a particular phenotype has been also successfully applied to heterogeneous disorders such as inherited peripheral neuropathy (IP).