Genetics and Phantom Limb Pain

Background:

- Many people who lose a limb feel pain in the missing limb. This feeling is called phantom limb pain. Researchers do not fully understand what causes this pain. Differences in people's genes may play a role. Comparing the genes of people with and without phantom limb pain may help researchers better understand this feeling, who is likely to develop it, and how to treat it.

Objectives:

- To study whether genetic differences affect phantom limb pain.

Eligibility:

- Individuals at least 18 years of age who have lost an arm or leg at least 3 months ago.

Design:

• Participants will be screened with a medical history and physical exam.
• Participants will answer questions about how they lost the limb, and whether they feel phantom limb pain. They will also have a test to measure their sensitivity to heat and cold.
• Participants will provide a blood sample for genetic testing.

Objectives:

The proposed clinical trial will investigate the role of the human genome including genetic variations and gene expression profiles on the development of phantom limb pain (PLP).

Study population:

Patients will be recruited from military personnel with major limb amputations. A total of one thousand subjects with upper or lower extremity amputations of any level will be enrolled in this study.

Design:

Eight hundred subjects with chronic PLP (PLP patient) and 200 patients without PLP (non-PLP patient) will assess the severity of their pain symptom. Each participant will undergo a routine blood draw from which DNA and RNA will be harvested.

Outcome measures:

Using Affymetrix SNP 6.0 technology, which identifies up to 1 million single nucleotide polymorphisms (SNPs) and 1 million copy number variations in the human genome, the differences in genomic variations between the PLP and the non-PLP patients will be analyzed. An extreme subset of PLP patients will be tested for their quantitative sensory function and profiled gene expression and epigenetic pattern with the Affymetrix Human Exon ST 1.0 and Illumina Genome Analyzer IIx. These integrative genomic analyses using genetic variations, gene expression and epigenetic profile could explain why some amputees experience chronic PLP and some do not. By studying these responses in patient samples, we will evaluate the role of genomic factors in PLP. SNP frequencies, gene expression and epigenetic profiles between PLP and non-PLP groups will be analyzed.

• Polymorphism-Genetic
• Amputation
• Pain

• Weinstein SM. Phantom limb pain and related disorders. Neurol Clin. 1998 Nov;16(4):919-36. Review.
• Sherman RA, Sherman CJ. Prevalence and characteristics of chronic phantom limb pain among American veterans. Results of a trial survey. Am J Phys Med. 1983 Oct;62(5):227-38.
• Montoya P, Larbig W, Grulke N, Flor H, Taub E, Birbaumer N. The relationship of phantom limb pain to other phantom limb phenomena in upper extremity amputees. Pain. 1997 Aug;72(1-2):87-93.

• INCLUSION CRITERIA:

PLP GROUP:

• at least 18 years of age
• Single or multiple upper and/or lower limb amputation
• At least three months post-amputation
• Ability to follow study instructions in English
• Currently present on-going PLP for at least one month and at least 3 times per week

NON PLP GROUP:

-same with PLP group except:

--Experienced PLP less than 10 times total and/or for less than two weeks

EXCLUSION CRITERIA:

BOTH PLP AND NON-PLP GROUPS:

• Chronic systemic disease which might affect pain sensitivity and ability to participate in this study's blood draw
• Any disease (such as hemophilia) or medication regimen (such as warfarin) increasing hemorrhage that would make a blood draw dangerous or inadvisable for the subject
• Known uncontrolled systemic diseases; known cancer not in remission, known on-going infection, lupus, kidney disease requiring dialysis, any other systemic disease which might affect ability to participate in this study's blood draw
• Inability to provide his/her own informed consent