MethylGuard is a good product. Add it slowly and carefully if you do not know the status of your other methylation genes.
MTHFR A1298C causes the body to have a harder time having enough BH4. BH4 is what the body uses to detox ammonia. Lyme generates ammonia as one of the many toxins it puts out. So the MTHFR A1298C variant will directly impact your ability to detox Lyme toxins.
To address this, Dr. Yasko has suggested taking biopterin, taking yucca root daily (especially with meals containing high protein foods), and doing charcoal/magnesium flushes weekly to mop up & clear out excess ammonia.
More info on her protocol can be found here:
www.dramyyasko.com/resources/autism-pathways-to-recovery/chapter-6/