Introns 10 and 11 of Lmna were deleted thereby abolishing production of lamin C and producing only prelamin A. Exon 12 was modified such that the Mir9 seed-binding sequence in prelamin A's 3' UTR (CCAAAG) was modified to ACCCTG. A floxed neomycin resistance cassette was inserted downstream of the modified exon 12. Western blot analysis confirmed the increased expression of lamin A protein in cerebral cortex and the cerebellum. (J:207144)