Her CBS theories are based on badly misreading research. The SNPs just have a minor impact. It is possible that sulfur problems are arising through a different mechanism, or that the gene is upregulated by external factors, but the SNPs themselves are mostly irrelevant. The treatment suggested by her for CBS might have an impact, but the basis of her justification for that treatment is completely groundless.
The AHCY SNPs which Yasko focuses on also have little or no impact.
Anyhow, I looked up the research for almost all of them at some point, and started threads in the
SNP subforum entitled "Interesting <gene name> Variations". So if you search for "Interesting MTHFR Variations" and "Interesting AHCY Variations" in that subforum, you'll find my lists of which 23andMe SNPs on those genes have an impact, and usually a brief discussion of research data which contradicts Yasko's conclusions. I haven't cited the research for most of those, but have lists of some of it on my laptop, and all of it can be found at google scholar or the research linked to the SNPs at
http://www.ncbi.nlm.nih.gov/projects/SNP/snp_ref.cgi?rs= . Snpedia.com is a good option if you want simpler but mostly accurate summaries.
At the end of the day, there's just too many inaccurate claims out there about SNPs to trust any of them. If you want to be certain, read the research yourself.