Are Head to Head Interstitial Telomeric Repeats Unique to Human Chromosome 2q13?

• D. Budinsky

  Author

The interpretation of human chromosome 2 as the product of an ancestral telomere to telomere fusion draws in part on a block of interstitial telomeric repeats at 2q13 that are arranged head to head, meaning that a forward oriented array of the hexamer TTAGGG meets a reverse oriented array of its complement CCCTAA at an inversion junction. A claim frequently made in popular presentations holds that this head to head arrangement occurs nowhere else in the human genome, and that its presence at 2q13 marks the fusion point. We tested that uniqueness claim directly. Before the test we had made a specific prediction: if interstitial telomeric repeats are a widespread and functional feature of the genome rather than fusion scars, then an inverted, head to head array should be found elsewhere, at a locus where no fusion has ever been proposed. Using a genome wide BLASTn survey we report inverted telomeric arrays on multiple chromosomes, and, most significantly, a head to head array on chromosome 9 whose junction is less interrupted than the one at 2q13. Because chromosome 9 is not proposed to be a fusion product, a cleaner inverted array there shows that the arrangement is not, by itself, diagnostic of a fusion. We first clarify a technical point essential to any test of the claim: because CCCTAA is the reverse complement of TTAGGG, both motifs are present at every telomeric locus, so their co occurrence is automatic and carries no information, and only a genuine inverted arrangement on a single strand is distinctive. The two regions are shown side by side, rendered in one font and colored by one criterion, so that the reader can compare them directly.

1. D. Budinsky

   Donny worked as a Registered Practical Nurse for many years. During his time working as an RPN, he converted to Christianity and became a Young Earth Creationist.

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