James Taylor received a B.S. in biology, magna cum laude, from Creighton University in 1991 and his M.D. with Honors in Research from the Medical College of Wisconsin in 1995. He then completed a residency in pediatrics at Washington University School of Medicine, during which time he was also a visiting registrar in pediatrics at the University of Malawai College of Medicine. Dr. Taylor came to the NIH and Johns Hopkins in 1998 for a clinical fellowship in pediatric hematology/oncology followed by postdoctoral fellowships at the National Cancer Institute, National Institute of Allergy and Infectious Diseases, and the NHLBI. He became a staff clinician at the NHLBI in 2004, and became an Assistant Clinical Investigator in the Hematology Branch in 2010. Dr. Taylor is also an attending physician at the NIH Clinical Center and staff attending physician at the Department of Pediatrics at the Johns Hopkins Hospital. He is a member of the American Academy of Pediatrics, American Pain Society, American Society of Hematology, American Society of Human Genetics, and Society for Clinical and Translation Science.
Sickle cell disease (SCD) is the most common genetic disorder in the United States, affecting approximately one in every 500 African American newborns. Yet while SCD arises due to defects in a single gene (HBB), people with this disease display a wide range of both the type and severity of their complications, which can include pain crises, strokes, and leg ulcers. The Taylor lab seeks to understand the additional genetic modifiers that contribute to SCD clinical outcomes, using a range of genetic and genomic approaches.
To identify additional genetic loci that may contribute to SCD severity, Dr. Taylor’s group is generating an extensive collection of genetic data from sickle cell patients enrolled in the Bethesda Sickle Cell Cohort Study, with the ultimate goal of acquiring DNA samples from at least 1,000 adults with SCD. They then employ techniques like admixture mapping to identify genetic markers associated with susceptibility differences among people with severe phenotypes, specifically people who have either very mild or very severe pain crises; pain crises are the most frequent SCD complication, accounting for about 90% of all SCD-related hospitalizations. Current efforts are focused on genetic variation within a set of single nucleotide polymorphisms (SNPs), though the group is also beginning to incorporate these data into the analysis of whole exome and whole genome sequencing of SCD patients with unique or rare phenotypes.
In addition to comparing gene variation, Dr. Taylor’s group is conducting comparative genomic studies of hemolysis, or presumed red blood cell (RBC) destruction. RBCs with the sickle cell mutation become more brittle and have a shorter lifespan because they burst open, though the range can still vary greatly; patients with short-lived cells tend to have more chronic problems like ulceration or pulmonary hypertension, while those with long-lived cells have more acute pain crises. His group is examining gene expression patterns of patients with either very short-lived or long-lived RBCs, as measured by circulating levels of lactate dehydrogenase, to determine patterns that may identify genes that influence clinical sub-phenotypes of SCD.
A third avenue of Dr. Taylor’s research involves analyzing candidate genes that may be markers for pain sensitivity. Instead of using frequency of hospitalizations as a standard for pain measurement, his group is employing an experimental pain phenotyping approach in human subjects known as quantitative sensory testing. In a pilot study, they are testing participants’ ability to tolerate physical stimulations such as heat or pinpricks and compare that to the genotype of candidate genes, in both SCD patients and healthy controls.
Together, these three distinct comparative studies will help reveal some of the subtle differences that dictate whether someone with the sickle cell HBB mutation can lead a relatively normal life or if they will experience severe and chronic complications.