A brain-derived neurotrophic factor polymorphism Val66Met identifies fibromyalgia syndrome subgroup with higher body mass index and C-reactive protein – Source: Rheumatology International, Jul 21, 2011
By Yangming Xiao, Jon Russell, Ya-Guang Liu
[Note (supplied by Co-Cure Listserv poster Kelly): “Subgrouping patients is important not only in ME and CFS, but other diseases and conditions as well. Subgrouping can be used to better target therapies as well as determining possible etiological differences. Brain-derived neurotrophic factor, also known as BDNF, is a protein that, in humans, is encoded by the BDNF gene. BDNF acts on certain neurons of the central nervous system and the peripheral nervous system, helping to support the survival of existing neurons, and encourage the growth and differentiation of new neurons and synapses.
“In the brain, it is active in the hippocampus, cortex, and basal forebrain – areas vital to learning, memory, and higher thinking. BDNF itself is important for long-term memory. BDNF was the second neurotrophic factor to be characterized after nerve growth factor (NGF). Despite its name, BDNF is actually found in a range of tissue and cell types, not just in the brain.”]
A common single nucleotide polymorphism (SNP) in the gene of brain-derived neurotrophic factor (BDNF) results from a substitution at position 66 from valine (Val) to methionine (Met) and may predispose to human neuropsychiatric disorders. We proposed to determine whether these BDNF gene SNPs were associated with fibromyalgia syndrome (FMS) and/or any of its typical phenotypes.
Patients with FMS (N = 95) and healthy normal controls (HNC, N = 58) were studied. Serum high-sensitivity C-reactive protein (hsCRP) levels were measured using an enzyme-linked immunosorbent assay (ELISA). [C-reactive protein levels in the blood rise in response to and are a marker of systemic inflammation.]
The BDNF SNPs were determined using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).
The BDNF SNP distribution was 65 (68%) Val/Val, 28 (30%) Val/Met, and 2 (2%) Met/Met for FMS and 40 (69%), 17(29%), and 1 (2%) for HNC, respectively. The serum high-sensitivity C-reactive protein (hsCRP) and body mass index (BMI) in FMS were higher than in healthy normal controls.
The FMS with BDNF Val66Val had significantly higher mean BMI (P = 0.0001) and hsCRP (P = 0.02) than did FMS carrying the Val66Met genotype.
This pattern was not found in healthy normal controls. Phenotypic measures of subjective pain, pain threshold, depression, or insomnia did not relate to either of the BDNF SNPs in FMS.
The relative distribution BDNF SNPs did not differ between FMS and healthy normal controls. The BDNF Val66Met polymorphism is not selective for FMS.
The BDNF Val66Val SNP identifies a subgroup of FMS with elevated hsCRP and higher BMI. This is the first study to associate a BDNF polymorphism with a FMS subgroup phenotype. [A phenotype is a gene-associated type with distinctive characteristic(s).]
Source: Rheumatology International, Jul 21, 2011. PMID:21773883, by Xiao Y, Russell IJ, Liu YG. Department of MedicineClinical Immunology, University of Texas Health Science Center at San Antonio, Texas, USA. [Email: firstname.lastname@example.org]