Xian Chang
@xian-chang.bsky.social
160 followers 140 following 9 posts
Bioinformatics postdoc at INRAE in Toulouse, France. Working on data structures and algorithms for pangenome graphs
Posts Media Videos Starter Packs
Reposted by Xian Chang
benlangmead.bsky.social
I've added 7 videos to my Burrows-Wheeler indexing playlist (www.youtube.com/playlist?lis...), rounding out the r-index series and adding a 5-part series on the move structure. Now 27 videos in that playlist. I aim to add videos on prefix-free parsing, PBWT, Wheeler languages/automata in the future.
Burrows-Wheeler Indexing - YouTube
Videos on : (a) the Burrows-Wheeler Transform (BWT), (b) the FM Index, which uses the BWT to construct a full-text index, (c) Wheeler graphs, (d) r-index, an...
www.youtube.com
xian-chang.bsky.social
Big thanks to everyone involved in the paper! @benedictpaten.bsky.social @adamnovak.graphs.vg Jordan Eizenga @jltsiren.bsky.social @jmonlong.bsky.social @shlokanegi.bsky.social Francesco
Andreace @sagorika03.bsky.social @kokyriakidis.bsky.social Glenn Hickey, Stephen Hwang, Emmanuele Delot
xian-chang.bsky.social
My favorite part: co-linear chaining in cyclic graphs using zip code trees, a new data structure for quickly finding distances in the graph that best match corresponding distances in the read
A cartoon of a variation graph and a sequencing read with seed alignments between the read and graph. The snarl tree corresponding to the variation graph is shown to the right. Below is the zip code tree representing the seeds, snarl and chain boundaries, and the distances among them.
xian-chang.bsky.social
Also featuring a cool demo of pangenome-guided regional assembly of complex loci from @shlokanegi.bsky.social Francesco Andreace @sagorika03.bsky.social @kokyriakidis.bsky.social
xian-chang.bsky.social
🦒Long read giraffe is out!🦒
Mapping long reads to pangenome graphs is ~10x faster than with GraphAligner, with veeery slightly better mapping accuracy, short variant calling, and SV genotyping than GraphAligner or Minimap2
biorxiv-bioinfo.bsky.social
Rapid, accurate long- and short-read mapping to large pangenome graphs with vg Giraffe https://www.biorxiv.org/content/10.1101/2025.09.29.678807v1
Reposted by Xian Chang
bchang32.bsky.social
Republicans are shutting down the government to stop you from having healthcare—there’s the message!!!!
Reposted by Xian Chang
robp.bsky.social
Last talk of the day (before posters) "Lossless Pangenome Indexing Using Tag Arrays" presented by Parsa Eskandar! #WABI25
xian-chang.bsky.social
Huge thank you to my incredible advisor @benedictpaten.bsky.social at @ucscgenomics.bsky.social for all his support and guidance, and to my committee David Haussler, @russcd.bsky.social, and @jianma.bsky.social
xian-chang.bsky.social
I'm very excited to share that I defended my thesis this week! I helped develop algorithms to combat reference #bias and make genomics more #equitable and #representative by incorporating genetic #diversity into genomics pipelines
Reposted by Xian Chang
jltsiren.bsky.social
We use personalized references with our Giraffe aligner. Each chromosome is partitioned into a sequence of blocks. We sample the most relevant haplotypes in each block using kmer counts. Mapping to this personalized reference improves variant calling accuracy. www.nature.com/articles/s41...
Personalized pangenome references - Nature Methods
This work introduces a k-mer-based approach to customizing a pangenome reference, making it more relevant to a new sample of interest. This method enhances the accuracy of genotyping small variants an...
www.nature.com
Reposted by Xian Chang
standupforscience.bsky.social
Welcome to the Bluesky account for Stand Up for Science 2025!

Keep an eye on this space for updates, event information, and ways to get involved. We can't wait to see everyone #standupforscience2025 on March 7th, both in DC and locations nationwide!

#scienceforall #sciencenotsilence
xian-chang.bsky.social
New figure for my thesis showing why Giraffe is the best long read pangenome mapper. No further evidence will be provided.
Variation graph representing the names of long read pangenome mappers: MiniGraph, GraphChainer, GraphAligner, PanAligner, and Giraffe
Reposted by Xian Chang
ucscgenomics.bsky.social
Researchers at @ucsantacruz.bsky.social have demonstrated how long-read sequencing could improve detection of diseases that have eluded diagnosis, at a fraction of the cost. New clinical tests could be on the way.
🗞 news.ucsc.edu/2025/01/pate...
👏🏼👏🏿👏🏾 @khmiga.bsky.social @benedictpaten.bsky.social
Quote: Long read sequencing is likely the next best test for unsolved cases... It can serve as a single diagnostic test, reducing the need for multiple clinical visits and transforming a years-long diagnostic journey into a matter of hours. Shloka Negi, UC Santa Cruz