Outline of the experimental process. Genomic DNA samples were digested by restriction enzymes. Ditags (paired-end tags) were collected from both ends of restriction fragments and sequenced. The ditag sequences were compared to known human reference genome sequences. The unmapped ditags were used as sense and antisense PCR primers to amplify their original DNA fragments to generate full-length sequences. The sequences were mapped to reference genome sequences to determine the type of genomic aberrations.