Sequence Homology And Genetic Recombination Between 4q35 And 10q26

There is a high level of sequence homology (98-100%) between D4Z4 repeats from the 4q35 and the 10q26 D4F104S1 loci. DNA sequencing was successful in identifying a unique BluI restriction site present only in each copy of the 10q26-derived repeat units[10] and a XapI site in all 4q35-derived repeats.

The high degree of homology between the 4q35 and the 10q26 D4F104S1 region is thought to have been responsible for interchromosomal exchanges between these two regions. In fact, complete repeat arrays (either of 4q35-derived BlnI-resistant D4Z4 repeats, or 10q26-derived BlnI-sensitive repeats) may be exchanged between these chromosomal locations. These interchromosomal exchange events are best visualized by pulsed-field gel electrophoresis (PFGE) owing to the large size of the genomic fragments involved; such studies have shown that entire repeat arrays are ''translocated'' in the majority of cases[11] (Fig. 4). It is likely that the sequence exchange is mediated by gene conversion, rather than actual physical translocation. Regardless of the precise mechanism involved, subtelomeric sequence exchanges may also lead to the formation of hybrid arrays containing interspersed 4q-derived and 10q-derived repeat units.

Perhaps surprisingly, these dynamic subtelomeric interchanges do not appear to be associated with the expression of the FSHD phenotype, as these 4q35/?10q26 exchanges are evident in about 20% of normal individuals (Fig. 4).[11] It should be emphasized that FSHD only occurs when the greatly deleted D4Z4 repeats (whether

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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