More than half of individuals affected by rare genetic diseases do not receive a clear genetic diagnosis and, as a result, are unable to access appropriate treatments or targeted interventions that could improve their quality of life. Approximately 15% of genetic diseases are caused by variants that alter RNA splicing. Validating these types of variants typically requires analysis of the patient’s RNA, which is most easily obtained from accessible tissues such as blood or skin. However, 30% or 1,436 Mendelian disease genes are not expressed in these patient accessible materials due to tissue-specific gene expression. For example, most genes implicated in neurodevelopmental disorders are expressed in the brain, making direct analysis using brain tissues highly invasive and often unfeasible.

Emmylou’s research focuses on addressing these challenges and increasing the diagnostic yield for individuals with rare diseases by developing RNA-based tools to functionally assess and validate RNA variants. Her work employs CRISPR-based gene transactivation technologies to activate genes with tissue-specific expression that are normally silent in blood or skin cells. She also applies RNA-capture techniques using biotinylated probes to selectively enrich lowly expressed disease genes, allowing for deeper sequencing coverage in short-read RNA-seq analyses, and thus enabling robust analysis of splicing outcomes. For rare muscular disorders, Emmylou performs cellular transdifferentiation of skin cells into iMyotubes, a skeletal muscle-like cells, to enable expression and analysis of muscle-specific genes. For patients unable to provide blood or skin samples, she combines CRISPR prime editing and CRISPR gene transactivation in easy-to-culture cell lines, such as HEK293T, to recreate patient variants and activate the corresponding disease gene. This approach enables functional validation and potential diagnosis without requiring invasive biopsies.

Beyond diagnosis, Emmylou is also interested in developing personalised therapeutic strategies for patients with dominant heterozygous loss-of-function variants. In these cases, one copy of a gene is affected, and the remaining healthy copy is insufficient to maintain normal function. By using CRISPR gene transactivation to upregulate the expression of the healthy allele, Emmylou aims to restore gene dosage and potentially ameliorate disease-associated phenotypes. Ultimately, Emmylou’s work seeks to bridge genetic diagnostics and translational medicine, paving the way for improved diagnosis, understanding, and treatment of rare genetic diseases.