Several family studies of RLS suggest an increased occurrence (as much as 60%) in first-degree relatives of idiopathic RLS cases (those not associated with other diseases and for which no causes are found). The presence of similar symptoms in such a high percentage of patients suggests that RLS follows a dominant mode of inheritance. As a consequence, half the siblings are at increased risk for developing RLS. First- and second-degree relatives of RLS patients are affected more often than controls. It is estimated that the first-degree relatives of RLS patients are five times more likely to have RLS than the nonrelatives. This risk is particularly apparent in patients with an early age of onset of RLS (before the age of 45 years).
Many studies do indicate that RLS runs in families, although this finding may be due to either familial occurrence or a shared common environmental factor. As yet, researchers have not precisely determined the exact risk of RLS occurring in close relatives. The recent genome-wide association study for RLS identified common variants in certain genomic regions, con-firming more than a 50% increase in risk for RLS in persons with these variants. Various investigators have examined the DNA in chromosomes and discovered a similar genetic makeup in people with RLS, and one that is different from the genetic makeup of those per-sons who do not have RLS. These studies have pointed to several locations in the chromosomes that might hold genes responsible for RLS, although no specific genes have been uncovered as yet.
It is clear from the various studies that RLS is a complex disorder that may result from a number of genetic and environmental factors. Therefore, it is not possible to give an absolute answer as to whether you will inherit RLS from your mother, but you do have a greater chance of doing so than persons whose parents do not have RLS.