Sequence analysis of genomic DNA from mutant mice showed showed a 7.1 kb LINE 1 sequence bordered at both ends by a direct repeat from the integration site within an exon that encodes the eigth EGF-like motif of the Reln protein. Nucleotide sequence analysis of showed that the LINE insertion caused this exon to be skipped during transcription leading to a 220 bp deletion in the Reln mRNA. (J:34099)