In the present study the investigators will search for new genetic variants relevant for the development of neuropathic pain.

Neuropathic pain is defined as "pain caused by a lesion or disease of the somatosensory nervous system". Neuropathic pain is a huge health problem worldwide, with an estimated prevalence of 7-8 % in the general population. In the present study the investigators will search for new genetic variants relevant for the development of this type of pain.

Peripheral nerve lesions only progress to neuropathic pain in some patients, yet is not completely understood why or how. Genetic studies of patients with rare neuropathic disorders have been important for elucidating novel molecular mechanisms of neuropathic pain, and new drugs for neuropathic pain are now being developed based on these findings. By using genetic association studies, one may identify new genetic variants which may help to identify key molecular mechanisms for a larger group of patients with neuropathic pain.

This project will use existing population-based cohorts, as well as establish a specific registry and biobank for patients with neuropathy in order to address these specific needs. This will allow the investigators to identify a large number of individuals with probable neuropathic pain and individuals with pain-free peripheral neuropathy (disease controls). International collaboration will contribute to study a large group of patients, which will be important in order to reach the project's goals. The results from the project are expected to increase current knowledge on the mechanisms of neuropathic pain, opening up new opportunities for innovative and improved treatments.

Dissemination of results will be organized in close collaboration with patient representatives, and will be done regularly throughout the course of the project. The will focus both on internal dissemination to the participating hospitals, and external dissemination through participation in conferences, submissions to scientific journals and by publishing patient-friendly information booklets and proactively informing media outlets and patient organizations.

Inclusion Criteria:

1. The patient is between 18 and 70 years old.
2. The patient has consented.
3. The patient is referred for evaluation of possible distal symmetric polyneuropathy (DSPN).
4. The patient has filled out the questionnaires.

Exclusion Criteria:

1. The patient is too sick to participate (eg. bedridden, fever).
2. The patient is unable to consent (eg. dementia, speech problems, psychiatric disorder).
3. Inflammatory acute polyneuropathy.

All patients that are referred for suspected distal symmetric polyneuropathy and meet the inclusion criteria, will be included in the project. Furthermore, there will be collected blood tests from patients with definite and probable polyneuropathy.