Figure 6.

HTT insertions tend to be enriched adjacent to themselves. (A) The observed frequency with which two HTTs neighbor each other relative to the expected frequency (log₂). (B) Boxplots of the posterior distributions describing the degree to which elements tend to neighbor themselves (log₂). The whiskers reflect the 95% credible intervals. (C) A visualization of the HTT subfamilies, depicted as thick bars, in the X chromosome telomere of the Release 6 reference. We depict alignments with at least 90% identity to the consensus; if a region is homologous to two elements, we assign it to the element with the greatest homology, which was only an issue due to some homology between TART-A and TART-C. The upward ticks indicate the 3ʹ-end of an element and the downward ticks the 5ʹ-end; a full-length insertion has both ticks. TART-A_PNTR is the TART-A Perfect Near-Terminal Repeat. (D) Top: The observed proportion with which each subfamily is found anywhere in the telomere (white) or is the first HTT found at the base of a telomere (gray). The error bars are 95% credible intervals computed analytically for Dirichlet-Multinomial models with uniform priors. Bottom: Boxplots summarizing posterior samples of the relative enrichment (log₂) of each subfamily at the base of the telomere, accounting for telomere composition differences across strains. The whiskers span the 95% credible interval, determined as quantiles of the posterior sample.