I am the Evelyn Willing Bromley Professor of Pediatric Pathology and Laboratory Medicine and Chief of the Division of Genomic Diagnostics at The Children's Hospital of Philadelphia. My research is focused on the genetics and diagnosis of rare pediatric disorders, with a longstanding program on the genetics of Alagille syndrome (ALGS). As PI of several University, Foundation and NIH-funded grants, my laboratory identified the disease genes (Jagged1 and Notch2) responsible for this autosomal dominant, multi-system disorder and we have worked to better understand the genes and the clinical features of this disorder. We defined the mutation spectrum for each gene, described the range of clinical features associated with these variably expressed disorders, and worked to investigate the variable expressivity, particularly with respect to liver disease, identifying potential genetic modifiers of liver disease severity. My laboratory has also worked on the molecular basis of other pediatric disorders including biliary atresia, ring chromosomes, and a variety of chromosomal syndromes and as part of a program project grant to apply exome/genome sequencing to pediatric disorders, as this technology was being introduced to the diagnostic world. Currently, I am focused on increasing the use of genomic technologies to diagnose pediatric disease, and technologies to decrease uncertainty in genomic diagnostics. I currently serve as a Managing Editor for the Journal Human Mutation and have worked closely and as a member of the Scientific Advisory Board for the Alagille syndrome Alliance, and served on multiple committees and on the Board of Directors of the American Society of Human Genetics.