Figure 1.

Example of a STR. A STR is a segment of DNA with a strong periodic pattern. A segment of DNA is defined as STR if (1) the minimum length is 9 bp, (2) a sequence motif (e.g., AT in ATATATATAT) is repeated at least three times, (3) there are only few base pairs that do not match the periodic motif (see Methods). The example shows an exonic STR region located in the nestin (NES) gene on chromosome 1.