Charge transport through an eight-base pair methylated DNA strand and its native counterpart have been investigated. We focus on three factors, contact coupling, decoherence and temperature, which can contribute to DNA charge transport. Our results show that with the same choice of contact coupling, in the phase-coherent limit the transmission of the methylated strand is smaller in the bandgap at energies close to the highest occupied molecular orbital (HOMO), while inside the HOMO band, the transmission is oscillatory and the methylated DNA may have a larger transmission in certain energy windows. The trend in transmission also holds in the presence of the decoherence though there is a crossover in the transmission of the native and methylated strands away from the HOMO level. We also find that the transport depends on the strength of contact coupling and the measurement temperature.