Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.
One example is below.
Q: In 1582 the united provinces invited francis, duke of anjou to lead them; but after a failed attempt to take antwerp in 1583, the duke left the netherlands again. after the assassination of william of orange (10 july 1584), both henry iii of france and elizabeth i of england declined the offer of sovereignty. however, the latter agreed to turn the united provinces into a protectorate of england (treaty of nonsuch, 1585), and sent the earl of leicester as governor-general. this was unsuccessful and in 1588 the provinces became a confederacy. the union of utrecht is regarded as the foundation of the republic of the seven united provinces, which was not recognized by the spanish empire until the peace of westphalia in 1648.
A: In what year did francis, duke of anjou leave the netherlands?
Rationale: The generated question is perfect. Because the question is based on second sentence of the input passage and its answer is 1583.
Q: Recent genome-wide association studies (GWAS) for Caucasians identified several allelic variants associated with increased risk of developing restless legs syndrome (RLS), also known as Willis-Ekbom disease. Although the pathogenic mechanisms of RLS are not entirely understood, it is becoming increasingly evident that many diseases such as RLS can be attributed to an epistasis. The study objectives were to evaluate whether the associations of RLS with all loci determined in previous GWAS for Caucasians can be replicated significantly for the Korean population and to elucidate whether an epistasis plays a role in the pathogenesis of RLS. DNA from 320 patients with RLS and 320 age- and sex-matched controls were genotyped for variants in the RLS loci. A significant association was found for rs3923809 and rs9296249 in BTBD9 (P < 0.0001 and P = 0.001, respectively); the odds ratio (OR) for rs3923809 was 1.61 (P < 0.0001) to 1.88 (P < 0.0001) and the OR for rs9296249 was 1.44 (P = 0.001) to 1.73 (P = 0.002), according to the model of inheritance. The OR for the interaction between rs3923809 in BTBD9 and rs4626664 in PTPRD was 2.05 (P < 0.0001) in the additive model, 1.80 (P = 0.002) in the dominant model and 2.47 (P = 0.004) in the recessive model. There was no significant association between genotypes of all tested single nucleotide polymorphisms and the mean value of serum iron parameters. Our results suggest that the role of BTBD9 in the pathogenesis of restless legs syndrome is more universal across populations than previously reported and more efforts should be focused on the role of epistasis in the genetic architecture of restless legs syndrome.
A:
Willis-Ekbom disease is also known as?