 It remains a possibility that some, or even most of these cases, may be R-L278* (R1b1*), R-L389* (R1b1a1*), R-P297* (R1b1a1a*), R-V1636 (R1b1a1b), R-PH155 (R1b1b), R1b* (R-M343*), R1a* (R-M420*), an otherwise undocumented branch of R1 (R-M173), and/or back-mutations of a marker, from a positive to a negative ancestral state, and hence constitute undocumented subclades of R1b.A compilation of previous studies regarding the distribution of R1b can be found in Cruciani et al.