There are many pathways.
But generally speaking, what's happening is that Phase I detoxification is sped up, while Phase II is slowed down. This creates a bottleneck of toxins that can't be eliminated, which then causes various symptoms.
See also the document in my signature link called the "SNPs Interpretation Guide". Ignore the first part about methylation and skip to the Detox SNPs section.
It covers the various genes of Phase I and Phase II detox, and what substances each gene detoxifies.
Note that your while your genetics have some impact, you also have to take into account epigenetics, which is the environmental influence on your gene expression.