Genetic studies investigating the link between ET and LRRK2 have yielded conflicting results: the LRKK2 I2012T, G2019S and I2020T variants have been found to be rare in Caucasians with ET18, while a comprehensive analysis of the LRRK2 gene found no association of common and rarer LRRK2 mutations or LRRK2 single nucleotide polymorphisms (SNPs) in ET cases or autopsy brain samples19. The gene discussed is LRRK2; the disease is essential thrombocythemia.