In[]:=
string=First@Import["C:\\Users\\arnoudb.WRI\\Downloads\\EPI_ISL_406223.fasta"];
In[]:=
rules=BlockMap[#[[1]]#[[2]]&,BlockMap[#&,Characters[string],12,6],2,1];Graph3D[rules]
Out[]=
In[]:=
rstring=Table[RandomChoice[{"A","C","G","T"}],StringLength[string]];rrules=BlockMap[#[[1]]#[[2]]&,BlockMap[#&,Characters[rstring],12,6],2,1];Graph3D[rrules]
Out[]=