Figure 1. . Complex repeat at the CNBP locus.

Figure 1.

Complex repeat at the CNBP locus. The CNBP repeat tract is a complex repeat comprising TG, TCTG, and CCTG tracts, in this order. Each repeat can vary in length.

On normal alleles, the overall length of the CCTG portion ranges from 11 to 26 tetranucleotide repeats and typically includes single interruptions (represented by the two vertical lines) that are variable in number (0-2), in location within the CCTG tract, and in repeat motif, but that commonly include individual GCTC and TCTG interruptions separately located within the CCTG tract.

On pathogenic alleles, only the CCTG repeat tract expands, without interruptions, resulting in overall repeat lengths of 75 to more than 11,000 pure CCTG tetranucleotide repeats.

From: Myotonic Dystrophy Type 2

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