Results
Within our study population, 46 out of 242 patients were tested for
MTHFR SNPs with 33 resulting positive for a known MTHFR polymorphism.
Patients with MTHFR genotypes including those who were homozygous 677TT
and compound heterozygous 677CT/1298AC demonstrated significantly
decreased tolerance to oral MTX as demonstrated by decreased maximum
tolerated MTX dosing relative to control and the 677TT genotype also
demonstrated reduced tolerance to IV MTX (Capizzi MTX). Clinically
significant MTHFR genotypes were likely to be detected in the presence
of myelosuppression, but no other known MTX adverse effects demonstrated
predictive ability. Lastly, no genotype was associated with increased
risk of developing MTX leukoencephalopathy or thrombosis with any SNP.