Combinatorial effects on gene expression at the Lbx1/Fgf8 locus resolve split-hand/foot malformation type 3.

Split-Hand/Foot Malformation type 3 (SHFM3) is a congenital limb malformation associated with tandem duplications at the LBX1/FGF8 locus. Yet, the disease patho-mechanism remains unsolved. Here we investigate the functional consequences of SHFM3-associated rearrangements on chromatin conformation and gene expression in vivo in transgenic mice. We show that the Lbx1/Fgf8 locus consists of two separate, but interacting, regulatory domains. Re-engineering of a SHFM3-associated duplication and a newly reported inversion in mice results in restructuring of the chromatin architecture. This leads to ectopic activation of the Lbx1 and Btrc genes in the apical ectodermal ridge (AER) in an Fgf8-like pattern induced by AER-specific enhancers of Fgf8. We provide evidence that the SHFM3 phenotype is the result of a combinatorial effect on gene misexpression in the developing limb. Our results reveal insights into the molecular mechanism underlying SHFM3 and provide conceptual framework for how genomic rearrangements can cause gene misexpression and disease.

The value of preoperative pharmacologic stress testing before vascular surgery using ACC/AHA guidelines: a prospective, randomized trial.

OBJECTIVE: To evaluate the validity of preoperative cardiac stress testing using clinical predictors from the American College of Cardiology/American Heart Association Guidelines on Perioperative Evaluation before Noncardiac Surgery in patients undergoing vascular surgery. DESIGN: Prospective, randomized pilot study. SETTING: Academic medical center. PARTICIPANTS: Patients undergoing elective abdominal aortic, infrainguinal, and carotid vascular surgery. INTERVENTIONS: After stratification by American College of Cardiology/American Heart Association (ACC/AHA) Guideline parameters, 99 patients were randomized to preoperative cardiac stress testing or to no stress testing and followed for up to 12 months postoperatively for adverse cardiac outcomes. MEASUREMENTS AND MAIN RESULTS: Before hospital discharge of 46 patients who underwent preoperative stress testing, 7 (15%) had inducible ischemia with no adverse postoperative cardiac outcomes, whereas only 1 (3%) of 39 patients (85%) with no ischemia had a nonfatal adverse cardiac outcome (p = not significant). Of 53 patients without preoperative stress testing, only 2 (4%) had a nonfatal adverse postoperative cardiac outcome. There were no cardiac deaths. At 12-month follow-up in 79 (80%) patients, there was 1 nonfatal adverse cardiac outcome (no stress test) and 1 cardiac death (abnormal stress test), reflecting a 1% 12-month cardiac morbidity and mortality. CONCLUSION: In this small prospective, randomized study evaluating the validity of preoperative cardiac stress testing using ACC/AHA Guidelines before major vascular surgery, preoperative cardiac stress testing offered no incremental value for determining postoperative adverse cardiac outcomes. Larger randomized clinical trials are needed to confirm these findings.