For genetic research to contribute more fully to furthering our knowledge of neuropathic pain, we require an agreed, valid, and feasible
approach to phenotyping, to allow collaboration and replication in samples of sufficient size. Results from genetic studies on
neuropathic painhave beeninconsistentand havemet with replication difficulties,inpartbecauseofdifferences inphenotypesused for
case ascertainment. Because there is no consensus on the nature of these phenotypes, nor on the methods of collecting them, this
study aimed to provide guidelines on collecting and reporting phenotypes in cases and controls for genetic studies. Consensus was
achieved through a staged approach: (1) systematic literature review to identify all neuropathic pain phenotypes used in previous
genetic studies; (2) Delphi survey to identify the most useful neuropathic pain phenotypes and their validity and feasibility; and (3)
meeting of experts to reach consensus on the optimal phenotype(s) to be collected from patients with neuropathic pain for genetic
studies. A basic “entry level” set of phenotypes was identified for any genetic study of neuropathic pain. This set identifies cases of
“possible” neuropathic pain, and controls,and includes:(1) a validatedsymptom-basedquestionnaire to determine whether any painis
likely to be neuropathic; (2) body chart or checklist to identify whether the area of pain distribution is neuroanatomically logical; and (3)
details of pain history (intensity, duration, any formal diagnosis). This NeuroPPIC “entry level” set of phenotypes can be expanded by
more extensive and specific measures, as determined by scientific requirements and resource availability.