$ cat pm_1079751_source1.gen 
C1, M1, 99999999, A, C, ... source1 info ...
C1, M2, 34787638, A, G, ... source1 info ...
C1, M3, 34787800, A, C, ... source1 info ...
C1, M4, 34787800, A, G, ... source1 info ...