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A genetic risk factor for periodic limb movements in sleep
Hreinn Stefansson1, David B Rye, Andrew Hicks
1deCODE Genetics, Reykjavik, Iceland. kstefans@decode.is
The New England Journal of Medicine
|July 20, 2007
Summary
Researchers identified a genetic variant linked to restless legs syndrome (RLS) and periodic limb movements in sleep. This discovery may explain about 50% of RLS cases and suggests a role for iron deficiency in the condition.
Area of Science:
- Genetics
- Neurology
- Sleep Medicine
Background:
- Restless Legs Syndrome (RLS) is a common neurological disorder causing an irresistible urge to move the legs, significantly disrupting sleep.
- Periodic Limb Movements in Sleep (PLMS) are common in RLS patients and serve as an objective physiological marker.
Purpose of the Study:
- To identify sequence variants contributing to the genetic basis of Restless Legs Syndrome.
- To investigate the genetic link between RLS, PLMS, and iron metabolism.
Main Methods:
- Conducted a genomewide association study (GWAS) and two replication studies.
- Focused on RLS patients with objectively documented PLMS to reduce phenotypic heterogeneity.
- Measured serum ferritin levels to assess iron status in relation to identified variants.
Main Results:
- A common variant in BTBD9 on chromosome 6p21.2 was significantly associated with RLS and PLMS across Icelandic and U.S. samples.
- This variant explained approximately 50% of the population attributable risk for RLS with PLMS.
- The variant showed a significant association with PLMS independent of RLS and was inversely correlated with serum ferritin levels, indicating reduced iron stores.
Conclusions:
- A genetic variant in BTBD9 is associated with susceptibility to PLMS.
- The identified variant's negative correlation with iron stores supports the hypothesis that iron depletion plays a role in the pathogenesis of RLS and PLMS.
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