GSTP1 does not modify MC1R effects on melanoma risk.

Glutathione Stransferases (GSTs) are a group of enzymes that act to detoxify reactive oxygen species resulting from oxidative stress processes and melanin production. GSTP1 is a polymorphic gene encoding variant proteins involved in metabolism. The role of the rs1695*A/G GSTP1 Ile105Val polymorphism in cutaneous malignant melanoma (CMM) susceptibility remains controversial. Two recent metaanalyses reported that the GSTP1 105Val allele was associated with an increased risk of CMM.1,2 However, it was concluded by the authors of both publications that additional studies with larger cohorts were required. The melanocortin 1 receptor (MC1R) gene encodes a Gprotein coupled receptor involved in the regulation of melanin production and the response to solar ultraviolet.3 MC1R RHCvariant alleles exercise major influence on hair colour, skin colour and sun sensitivity. The association between MC1R and susceptibility to CMM and skin cancer in general has been described previously.4,5 A 2011 Spanish study reported that the GSTP1 polymorphism was associated with light coloured hair and increased CMM risk. Furthermore, the authors described a greater penetrance of CMM risk when the GSTP1 105Val allele was combined with MC1R RHCvariant alleles.6,7