sentences:  In one example, involving "MLH1", Jiang et al.conducted a study where they evaluated the mRNA expression of 27 DNA repair genes in 40 astrocytomas compared to normal brain tissues from non-astrocytoma individuals.Among the 27 DNA repair genes evaluated, 13 DNA repair genes, "MLH1", "MLH3", "MGMT," "NTHL1," "OGG1," "SMUG1," "ERCC1," "ERCC2", "ERCC3", "ERCC4", "RAD50", "XRCC4" and "XRCC5" were all significantly down-regulated in all three grades (II, III and IV) of astrocytomas.