RFC, G₈₀A polymorphism: genotyping and its impact on ALL outcome and MTX levels.

(A) ASO hybridization assay of RFC1 G₈₀A polymorphism. PCR products of RFC1 gene obtained from the DNA of each patient are blotted in duplicate. The membranes are hybridized with ASO specific for G₈₀ (left panel) or A₈₀ (right panel). Hybridization signal in spots A1, A2, and C2 indicate homozygous patients with the GG genotype, in B2 a heterozygous patient with the AG genotype, and in B1 and C1 patients with the AA genotype. (B) Kaplan-Meier estimates of EFS for patients with and without the RFC1 A₈₀ variant. EFS curves for patients positive (lower line) or negative (upper line) for the RFC1A₈₀ variant are presented. The P value for the differences of survival between these patients groups is indicated. (C) Relationship between RFC1 G₈₀A polymorphism and MTX plasma level. Lines represent log values of MTX levels (μM, measured at 3 time points) in GG, GA, and AA genotypes. MTX levels differ across RFC1 genotype groups (P = .02). When MTX levels in patients with the AA genotype are compared with those of the rest of patients, the difference is .004.