Loss-of-function polymorphisms in NQO1 are not associated with the development of subacute myelo-optico-neuropathy

Background: Subacute myelo-optico-neuropathy (SMON) is a neurological disorder associated with the administration of clioquinol, particularly at very high doses. Although clioquinol has been used worldwide, there was an outbreak of SMON in the 1950s-1970s in which the majority of cases were in Japan, prompting speculation that the unique genetic background of the Japanese population may have contributed to the development of SMON. Recently, a possible association between loss-of-function polymorphisms in NQO1 and the development of SMON has been reported. In this study, we analyzed the relationship between NQO1 polymorphisms and SMON in Japan. Methods: We analyzed 125 Japanese patients with SMON. NQO1 loss-of-function polymorphisms (rs1800566, rs10517, rs689452, and rs689456) were evaluated. The allele frequency distribution of each polymorphism was compared between the patients and the healthy Japanese individuals (Human Genomic Variation Database and Integrative Japanese Genome Variation Database), as well as our in-house healthy controls. Results: The frequencies of the loss-of-function NQO1 alleles in patients with SMON and the normal control group did not differ significantly. Conclusion: We conclude that known NQO1 polymorphisms are not associated with the development of SMON.