Is it possible for your MC1R gene to produce eumelanin and then later in life start producing little or none?

Is it possible for your MC1R gene to produce eumelanin and then later in life start producing little or none, even switching to only produce phaeomelanin?  Or if you have one dominant and one recessive allele, is it possible that the recessive one could take over for part of your lifetime?

Until now the mechanism of natural change in hair color has not been fully understood. MC1R is a receptor present on a cell's surface that is responsible for further stimulation of eumelanin expression. It works by controlling the type of melanin being produced and its activation causes the melanocyte to switch from generating the yellow or red phaeomelanin by default to the brown or black eumelanin in replacement. There are some studies that showed differential regulation of MC1R gene expression (thus amount of produced eumelanin). Among the factors that are shown to decrease its expression, thus potentially reducing amount of eumelanin, are, for instance, testosterone, as well as UV radiation.

If you have one dominant and one recessive allele, the recessive one can not take over the function. A recessive gene can not become dominant.