Observed size ranges of the MSR arrays. For every MSR, a box plot illustrates the size range observed in all 210 unrelated individuals. The box indicates the upper and lower quartiles and the median is represented by a horizontal line within the box. The vertical lines show the full range of sizes observed for the MSRs. MSRs are very polymorphic with some showing a wide range of size variation (e.g. MSR5p) and others a much more limited variation (e.g. CT47). The mean repeat array size was also very variable; e.g. RS447 repeats contained on average 60 repeat units in contrast to e.g. FLJ40296 that consisted on average of 9 repeat units. For FLJ40296, RNU2, CT47, D4Z4 (4q) and D4Z4 (10q) MSR array sizes were not evenly distributed where skewness to the longer repeat sizes was observed. A minimum number of two repeat units is required to form a repeat array and this was found for D4Z4 (10q) and FLJ40296, but for the other MSRs higher minimum array sizes were observed. This minimum number of repeat units depended on the MSR and could be rather large, e.g. for RS447 and MSR5p where the shortest repeat array consisted of eight units.
Schaap et al. BMC Genomics 2013 14:143 doi:10.1186/1471-2164-14-143