Introduction: Restless legs syndrome (RLS) is a disease that frequently occurs in families, however, the incidence of the familial form as well as that of primary and secondary forms of RLS have not been studied in the Czech population. Differences in the clinical course and pathophysiological interpendences in the sporadic and familial forms as well as in idiopathic and secondary forms have not been elucidated yet.That is why we performed a study focused on the inheritance of RLS and selected clinical and laboratory parameters of this disease. Material and Methods: In RLS patients, clinical examination was complemented by investigation of haematological and biochemical indicators, including erythropoetin and soluble transferrin receptor levels. In each patient with positive family history, a focused pedigree was compiled. Results: The set of 116 RLS patients (59.5 % women, age 55.4 ± 12.1 years, mean ± SD) contains 31 patients (61 % women) with positive family history (age 54.6 ± 14.3 years). In patients with the familial form, a significantly lower age at symptom onset was found (p < 0.01). There were no significant differences in the other investigated parameters. In the subgroup with the familial form, the incidence of diseases causing secondary RLS was not significantly lower. In 21 pedigrees of non-related families, a total of 60 RLS patients was found (age 49.3 ± 14.4 years), 60 % were women. In 50 parental couples with a total of 106 children, the proportion of affected children is 40.5 %. Conclusion: Pedigree analysis shows evidence for autosomal dominant type of RLS inheritance with incomplete penetrance. In the Czech population, we confirmed a lower age at symptom onset in the familial form as the only clinical or laboratory indicator of a difference between sporadic and familial RLS forms.

        Key words: restless legs syndrome, laboratory parameters of RLS, pedigree study