Identification of Genomic Structures Involved in Chromosome 22q11.2 Deletion Syndrome
Wednesday, February 22, 2017
3:00 PM-5:00 PM
BIOMED PhD Research Proposal
Title:
Identification of Genomic Structures Involved in Chromosome 22q11.2 Deletion Syndrome
Speaker:
Steven Pastor, PhD Candidate, School of Biomedical Engineering, Science and Health Systems
Advisor:
Ming Xiao, PhD, Associate Professor, School of Biomedical Engineering, Science and Health Systems
Abstract:
Chromosome 22q11.2DS (22q11.2DS) is the most common human microdeletion disorder in humans and demonstrates wide phenotypic variability with affected individuals exhibiting significant medical problems. In most affected individuals, a de novo ~3 Mb deletion occurs from an aberrant recombination mediated by four chromosome-specific low copy repeats (LCRs) in the chromosome 22q11.2 region. The combination of large, near-identical segments makes the LCRs substrates in non-allelic homologous recombination (NAHR), leading to genomic rearrangements. Unfortunately, these same characteristics make the LCRs difficult to reliably sequence and identify rearrangement breakpoints within the homologous chromosome 22 LCRs in individuals with 22q11.2DS.
By leveraging the increased sensitivity afforded by long single molecule optical mapping on nanochannel arrays, coupled with 10XGenomics whole-genome sequence and molecular combing, this proposal will elucidate the previously unmapped structure and variation of the chromosome 22 LCRs and surrounding regions. This will provide enhanced insight into the role of LCRs in producing the 22q11.2DS and its associated phenotypes.
Our preliminary studies show variability in LCR structure via a 160kb module and the LCR-C to LCR-D inversion that have not been seen before. Typical sequencing approaches fail because the 160kb modules pile up and are not discriminated. The approach we propose will allow us to determine whether specific haplotypes predominate in the parent of deletion origin. This approach will likely represent a paradigm, providing resources for the analysis of numerous other significant regions of the genome that have failed accurate elucidation because of the presence and complexity of other LCRs, many of which cause disease.
Contact Information
Ken Barbee
215-895-1335
barbee@drexel.edu