GPX1 and cancer: For example, there is strong LD between the GPX1 P198L variant and variants in the nearby gene RHOA. Since RHOA belongs to the ras oncogene family and studies both in vitro and in vivo suggest that its overexpression may lead to cancer [53,54], it is possible that observed associations between the L198 variant and an increased risk of cancer may in fact be due to LD between this variant and as yet unidentified variants within RHOA or another nearby gene [51].