Fibromyalgia and Genetics
Fibromyalgia appears to run in families. This does not prove a genetic influence, since shared environmental factors could be responsible. However, there is considerable evidence of a genetic component to the disease. Fibromyalgia is a complex disease, influenced by multiple genes that interact with environmental factors such as stress. Some genetically determined traits that are implicated in fibromyalgia are:
Tissue Type (HLA): Contradictory results have been found when looking for a relationship between tissue type and incidence of fibromyalgia. Some studies have shown a strong association between certain HLA types and fibromyalgia, but others have found no evidence of this link.
5-HTT (serotonin transporter gene): a certain variant of this gene, known as the S/S genotype has been shown to be more common in fibromyalgia sufferers compared to healthy subjects.
Dopamine: this is an essential neurotransmitter involved in pain transmission. Increased sensitivity or density of dopamine receptors have been shown in fibromyalgia patients. This raises the possibility of using dopamine receptor agonists as a treatment for fibromyalgia.
MPHG: 3-methoxy-4-hydroxyphenethylene, a metabolite of norepinephrine, is lowered in fibromyalgia. This could explain less inhibition of pain transmission in fibromyalgia patients.
COMT: certain variants in the gene coding for this enzyme (catechol-O-methyl transferase) have been shown to be more common in fibromyalgia patients than healthy controls.
Substance P: this is a peptide neurokinin and is present at increased levels of the CSF of fibromyalgia patients.
Significant progress has been made toward understanding the mechanisms of this condition. Hopefully this expansion of knowledge will enable new treatments for fibromyalgia to be developed.