The focus of Dr. Keegan’s research laboratory is (1) to understand the role of telomere maintenance during development, (2) to understand the mechanisms by which telomere dysfunction causes distinct phenotypes in mice and humans, and (3) to understand the mechanisms that lead to birth defects affecting caudal structures in humans. She identified the gene that is mutated in acd mice, which encodes the telomere protein TPP1, a component of the shelterin complex that plays a critical role in both end-protection and end-replication of telomeres. Consistent with the known function of TPP1 as a critical component of shelterin, her laboratory showed that Acd-deficient cells exhibit evidence of telomere dysfunction and genomic instability. Her laboratory also determined that the skeletal anomalies observed in acd mutant embryos are due to p53-dependent apoptosis as a consequence of telomere dysfunction. In collaboration with Dr. Ivan Maillard’s laboratory, her laboratory also demonstrated a critical role for TPP1 in telomere end-protection in hematopoietic stem cells. Dr. Keegan is also interested in understanding the genetic basis of birth defects that affect the urogenital system and caudal region of the embryo. She has collected DNA samples from patients with a variety of caudal malformations, including caudal regression syndrome, OEIS (omphalocele–exstrophy of the bladder–imperforate anus–spinal defects) complex, and persistent cloaca malformation for whole genome analysis. In addition, her laboratory identified the mutation responsible for the Danforth’s short tail (Sd) mutation as a retrotransposon insertion causing ectopic expression of the Ptf1a gene during caudal development.