Genetics of restless legs syndrome

Restless leg syndrome, periodic limb movements, febrile seizures and Attention deficit hyperactivity disorder in an Indian family

Restless leg syndrome (RLS) is a common neurological disorder which can affect individuals of all age groups and incidence increasing with age. It can cause severe sleep disruption and negatively impact quality of life of an individual. Its diagnosis is clinical, based on essential criteria of International RLS Study Group. It can be idiopathic or associated with various medical and other neurological disorders. Idiopathic RLS can be sporadic or may have a familial inheritance, with several genetic loci been reported till date. RLS has a strong association with periodic limb movements, both sleep and awake. Very few studies of familial RLS/Periodic limb movements in sleep and their associations have been reported. We report an Indian family with autosomal dominant RLS/PLMS, with RLS and PLMS as well as psychiatric disorders, febrile seizures and Attention Deficit Hyperactivity Disorder in different family members, over three generations.

Clinical and genetic description of a family with a high prevalence of autosomal dominant restless legs syndrome

OBJECTIVE

To conduct clinical and molecular genetic analyses of the members of an extended family in Central Indiana with a high prevalence of restless legs syndrome (RLS).

PARTICIPANTS AND METHODS

From February 1, 2006, through August 31, 2008, we collected data from members of this family, which is of English descent. Genealogical methods were used to expand the family tree, and family members were screened with an RLS questionnaire. Telephone interviews and personal examinations were performed at Mayo Clinic and during a field trip to Central Indiana. Blood samples were collected for molecular genetic analysis. A follow-up telephone interview was conducted 1 year later.

RESULTS

The family tree spans 7 generations with 88 living members, 30 of whom meet the criteria for diagnosis of RLS established by the International Restless Legs Syndrome Study Group. Three affected family members also have Parkinson disease or essential tremor. The mode of RLS inheritance is compatible with an autosomal dominant pattern. The affected family members do not exhibit linkage to the 5 known RLS loci or mutations in the RLS susceptibility genes MEIS1 and BTBD9.

CONCLUSION

Of 88 members of this single extended family in Central Indiana, 30 were diagnosed as having RLS. Because our analysis shows that the disease is not linked to any of the known RLS loci or risk-associated genes, we postulate that members of this family may carry a gene mutation in a novel genetic locus.

Clinical and genetic description of a family with a high prevalence of autosomal dominant restless legs syndrome

OBJECTIVE

To conduct clinical and molecular genetic analyses of the members of an extended family in Central Indiana with a high prevalence of restless legs syndrome (RLS).

PARTICIPANTS AND METHODS

From February 1, 2006, through August 31, 2008, we collected data from members of this family, which is of English descent. Genealogical methods were used to expand the family tree, and family members were screened with an RLS questionnaire. Telephone interviews and personal examinations were performed at Mayo Clinic and during a field trip to Central Indiana. Blood samples were collected for molecular genetic analysis. A follow-up telephone interview was conducted 1 year later.

RESULTS

The family tree spans 7 generations with 88 living members, 30 of whom meet the criteria for diagnosis of RLS established by the International Restless Legs Syndrome Study Group. Three affected family members also have Parkinson disease or essential tremor. The mode of RLS inheritance is compatible with an autosomal dominant pattern. The affected family members do not exhibit linkage to the 5 known RLS loci or mutations in the RLS susceptibility genes MEIS1 and BTBD9.

CONCLUSION

Of 88 members of this single extended family in Central Indiana, 30 were diagnosed as having RLS. Because our analysis shows that the disease is not linked to any of the known RLS loci or risk-associated genes, we postulate that members of this family may carry a gene mutation in a novel genetic locus.

Restless Legs Syndrome in Hereditary Spastic Paraparesis

This study was designed to investigate the prevalence and determinants of the association of restless legs syndrome (RLS) and hereditary spastic paraparesis (HSP). Therefore, 132 patients with HSP were evaluated concerning the symptoms of RLS by a standardized questionnaire. RLS was supposed when patients met all of the established four essential criteria of RLS defined by the International RLS Study Group. In addition, we studied the relationship between RLS and age at HSP symptom onset and evaluated the severity of RLS symptoms. Out of 59 responses, RLS was found in 27 HSP patients (15 male, 12 female) so that RLS was more frequent in the total HSP group (20.5%; 27/132) than in previous population-based studies (about 11%). In all 27 patients, the diagnosis of RLS was established based on an additional personal interview. The probability to develop RLS did not increase with higher age. Age at onset of HSP symptoms in the HSP group with RLS (27.7 +/- 12.6 years) and the HSP group without RLS (37.0 +/- 16.9 years) differed significantly (p = 0.04). Most of the patients with RLS showed a moderate and severe grade on the RLS severity score. Only 8 patients had previously been diagnosed to have RLS and were on medication. The data of this screening for RLS provided evidence that patients with HSP are particularly susceptible to develop RLS. Consequently, special emphasis should be put on the diagnosis criteria of RLS in HSP patients.