Hi there,
Looking at your progress, it's clear that you don't need to be told this, but I thought I would share so as to hopefully prevent others from becoming discouraged. There is a more recent study that was published and found that OPRM1 genotype DOES NOT predict responsiveness to nal. The original study was retrospective. I cannot say why there are differences between results found in the two studies, but I can tell you that retrospective studies can very easily find correlations that have nothing to do with causation. They could have checked hundreds of targets, found this one to correlate, and were able to publish it because it was in a gene with a known link to addiction. It doesn't mean that it's actually causative though, could be a coincidence.
Just for fun I am going to sequence my OPRM1 gene anyway

Here is the new study:
http://www.ncbi.nlm.nih.gov/pubmed/21946895