Three studies have been made,two Italian groups revealed significant association of the rs1126671 locus in the ADH4 gene with CH incidence,one of the experiments have also found the association between the ADH4 SNP rs1800759 and CH,but those results were not confirmed in a large Swedish case–control cohort study [23–25]. The gene discussed is ADH4; the disease is cyclic hematopoiesis.