In our lab we are doing mutation studies for MTHFR677 AND MTHFR1298 by pcr. We code 83890 molecular diagnostics-molecular isolation or extraction, 83900 amplification target-multiplex first two nucleic acid seq., 83892 x2 enzymatic digestion, 83896 x4 nucleic acid probe, 83914 mutation identification by enzymatic ligation or primer extension, single segment, each segment and 83912 interpretation and report. The question I have is that the Lab Director is doing an interpretation for each mutation but is writing only one report so should we be billing one unit or two for 83912. Also, about 25% of the time only one mutation test is ordered so in that case it is clear that only one unit should be billed. It is when both mutation tests are ordered that it becomes confusing? Any thoughts on what is correct?