Genetic Component To Restless Legs Syndrome
Restless Legs Syndrome (RLS) is a common cause of insomnia, affects somewhere between 5 and 10% of white North Americans, and tends to coexist with certain other medical ailments, such as fibromyalgia syndrome (FMS). Because so many are afflicted by tossing and turning at night due to RLS, the medical community has sought to learn more about the condition in hopes of discovering better treatment options. One piece of the RLS puzzle has been borne out again and again during various research studies: restless legs syndrome is linked to genetics.
Various studies concentrating on how RLS occurs in the general population, in families, and in twins, have been consistent in suggesting an inherited tendency to the condition. The latest study aimed to determine the risk factors for restless legs syndrome and concentrated on French Canadian families who appear to have a higher incidence of RLS.
An article about the study appeared in the April 2009 issue of the Archives of Neurology, a journal put out by the JAMA Archives. The published report of the study states that a gene linked to a high risk for RLS was found on chromosome 12q. The researchers believe that one or more other genes may also be implicated in RLS.
University of Montreal's Alex Desautels, PhD, and his team looked at the DNA of 19 French Canadian families and made comparisons with the DNA of from 4-9 confirmed or suspected RLS patients of non-French Canadian heritage. The research team then applied statistical analysis to see whether the genetic information of the families matched markers at the same location on chromosome 12q, found earlier to have an association with RLS.
The total number of participants in the study numbered 276. This figure includes 146 confirmed sufferers of RLS, 39 possibly afflicted with the condition, and 91 relatives who do not have RLS. Within five of the families, instances of the ailment were found to have a confirmed link to chromosome 12q. In six other families, the link to chromosome 12q was ruled out.
The researchers then examined the clinical findings in those participants with RLS from the various families to determine if differences in clinical findings could be linked to a corresponding variability in chromosomal markers. The team determined that the symptom of intermittent leg movements during the sleep state was seen more in RLS patients from families linked to chromosome 12q than in those who had no such linkage.
The authors of the study stated that, "These results further support the involvement of an RLS-susceptibility locus [gene location] on chromosome 12q in the FC [French Canadian] population and also provide evidence that there must be other loci involved in this common sleep disorder. Furthermore, our findings illustrate that extensive characterization of subclinical differences represents a major tool in the identification of susceptibility loci for complex diseases."
The researchers concluded that it looks as though the genetic background of RLS is going to prove complex, but hope their findings will provide a new avenue for research on the genetic causes of restless legs syndrome.