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Glutathione S-transferase gene deletions in myelodysplasia

Chen and colleagues reported on the frequency of null genotypes for the glutathione S-transferases GSTM1 and GSTT1 genes showing a significantly increased frequency of the null genotype for the GSTT1 gene in patients with myelodysplastic syndrome (MDS).1 These enzymes play a role in the metabolic pathway for carcinogens and it is important for Chen et al’ s findings to be confirmed. We determined the frequency of the null genotypes in a large group of controls (haematologically normal UK laboratory staff and UK general medical outpatients) and patients with primary MDS. We found no significant difference in frequency between controls and patients for either GSTM1 (odds ratio 0· 89 [95% CI 0· 5– 1· 43]) or GSTT1 (odds ratio 0· 72 [95% CI 0· 4– 1· 34]) null genotype frequency (table). There was no suggestion of any difference in frequencies within the different MDS subgroups. We also looked at eight cases of secondary MDS and found 4/8 to have the GSTM1 null genotype. The reason for the discrepancy between our findings and those of Chen are not clear.2 There is the possibility of racial heterogeneity in studies from the USA causing skewed results but other possibilities include, for example, different causes of MDS in different countries.

glutathione S-transferase gene; mylodysplasia; leukaemia

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