Human centromere variation and function - Project Summary/Abstract The equal segregation of chromosomes during cell division ensures the accurate inheritance of genetic information. Aberrant chromosome segregation can cause an imbalance in chromosome number, or aneuploidy, which can result in spontaneous abortion and birth defects and is a major cause of cancer. The locus required for the equal segregation of chromosomes is the centromere. In humans, centromeres are comprised of repetitive α-satellite sequences that span several megabases on each chromosome. The repetitive nature of these regions has challenged efforts to determine their sequence, structure, and variation using short-read sequencing data. As a result, we have a very limited understanding of the natural variation of centromeres and the impact of this variation on essential cell biological process critical for life. In this proposal, I aim to address this gap in knowledge by sequencing and assembling centromeres from diverse humans using a combination of long-read sequencing technologies and novel computational assembly tools (Aim 1; K99 phase). Additionally, I propose to assess the natural variation of human centromeres at the genetic, epigenetic, and transcriptional level using innovative computational methods and multiomic sequencing approaches, ultimately building a model of human centromere variation (Aim 2; K99 phase). Finally, I propose to determine how variation among centromeres affects the accurate segregation of chromosomes during cell division using cell-based assays, long- read sequencing, and multiomic sequencing approaches (Aim 3; R00 phase). Together, this work will provide the first comprehensive assessment of human centromere variation and reveal how this variation affects centromere function in cells. The tools, resources, and skills developed in the K99 phase will be applied in the R00 phase to determine the functional consequences of centromere variation and its role in human health and disease. My goal is to build an independent research program that spans the gap between genomics and centromere biology. I will receive the necessary interdisciplinary training from my mentor (Dr. Evan Eichler), co- mentor (Dr. Sue Biggins), and the rest of my postdoctoral advisory committee (Drs. Deborah Nickerson, Andrew Stergachis, and Kelley Harris). In addition, I will participate in career development activities offered through the University of Washington and the Fred Hutchison Cancer Research Center. Together, my research training, mentors, advisory committee, and academic environment will prepare me well as I transition to an independent position as an academic scientist.