Relevant Degree Programs
Affiliations to Research Centres, Institutes & Clusters
Great Supervisor Week Mentions
Can't let great supervisor week at UBC pass without saying thank you to Dr. Cheryl Gregory-Evans. So proud to work with her. With her patience, understanding and great attitude, I built confidence and self-esteem in research and science in general. She created just the perfect environment for any individual in her lab and despite all her other commitments, she sets aside time for each member to discuss progress and be there whenever they need her. I always get inspired by her passion in running a marathon and sharing with us all the efforts she put ( proud of her). I'm grateful to have a brilliant, wise and super competent supervisor.
Thank you for making my graduate journey at UBC wonderful and invaluable.
Graduate Student Supervision
Doctoral Student Supervision (Jan 2008 - May 2021)
No abstract available.
Small gains and losses of chromosomal DNA, called copy number variants (CNVs), are the cause of many human developmental abnormalities detected before or after birth. Clinically-significant CNVs are found in 2-6% of developmentally arrested embryos and fetuses (termed miscarriage) and in ~15% of children with postnatal developmental abnormalities, typically including abnormal brain function and leading to neuro-developmental delay (NDD). The overall goal of my PhD project was to characterize CNVs found in both miscarriages and in children with NDD in order to identify candidate genes that cause these two aspects of abnormal development. I used a multi-faceted approach consisting of bioinformatics, human cell-line analysis and transgenic animal model investigations. I characterized CNVs reported in miscarriages from literature as well as from our laboratory by using bioinformatics approaches to determine the CNVs size, gene content, gene density and function, known gene knockout murine phenotype, and biological pathway enrichment for all miscarriage CNV genes. My analysis identified several genes from miscarriage CNVs with important functions during prenatal development and pregnancy (e.g. CDKN1C and TIMP2) and enrichment of genes from miscarriage CNVs in biological pathways and processes relevant to embryo/fetal development and feto-maternal interaction (e.g. immune response). For discovery of candidate genes responsible for childhood NDD, I characterized CNVs mapping to a chromosome region, 2p15p16.1, which are known to be associated with multiple postnatal developmental abnormalities and NDD (termed 2p15p16.1 microdeletion syndrome). I performed detailed phenotype and CNV analysis of 33 patients with 2p15p16.1 microdeletions and identified 3 candidate genes (XPO1, REL, and BCL11A) for the developmental problems. By studying their expression in patient cell-lines as well as phenotypic consequences of the loss or gain of their expression in zebrafish, I confirmed their role in developmental abnormalities associated with this syndrome. I have also explored the role of non-coding sequences from this CNV in regulation of one of the candidate genes, BCL11A. The results of my study provide a blueprint for identification of genes with a role in abnormal development by characterizing CNVs. Understanding the cause of the developmental abnormalities opens paths for exploring possibilities for their improved diagnosis, prevention, and potential cure.
Master's Student Supervision (2010 - 2020)
Ocular coloboma is a condition caused by a malformation in optic fissure formation during early eye morphogenesis. It is characterized by visual impairment and in some instances, blindness in some children. The prevalence of ocular coloboma is estimated to range from 2 to 14 per 100,000 children. Although many pathways are known to play an important role in optic fissure closure, the mechanisms and genetic regulation driving optic fissure closure during development are still not widely understood. Different factors are associated with ocular coloboma, including genetic predisposition and environmental influences. The Wingless and Int1 (WNT) signalling pathway is conserved among vertebrates and plays an important role in regulating different developmental processes, including eye development. When the pathway is in a stimulated state, presence of WNT ligand binding to its receptor, results in deactivation of the complex consisting of APC, Axin and GSK3. This deactivation leads to accumulation of the cytoplasmic β-catenin that is translocated into the nucleus and activates transcription of target genes. Fzd5 gene plays an important role in eye morphogenesis during early stages of development. We hypothesized that abnormal levels of WNT signalling is driving the ocular coloboma phenotype. Here, we over-activated the WNT signalling pathway using the small molecule Bromoindirubin-3′-oxime (BIO) and lithium chloride (LiCl), which have been previously shown to impact this pathway. Multiple doses of LiCl treatment has a sensitivity period of disrupting WNT signalling pathway that lead to coloboma phenotype. On the other hand, BIO treatment lead to molecular disruption of WNT signalling pathway with normal eye development. Over-activation of WNT signalling was confirmed by the expression level of GSK3 and ß-catenin using western blot. Secondly, we generated a stable WNT mutant zebrafish line (fzd5) using CRISPR/Cas9 technology and observed coloboma phenotype by brightfield microscopy. This study demonstrated that overexpression of WNT signalling had a dose-dependent response and sensitivity period effect that lead to abnormal eye development both coloboma and microphthalmia phenotype in zebrafish model. Moreover, we demonstrated that zebrafish is an excellent model for CRISPR gene knockout of ocular developmental genes.