Marko T. Boskovski

The heterotaxy gene GALNT11 glycosylates Notch to orchestrate cilia type and laterality

Heterotaxy is a disorder of left–right body patterning, or laterality, that is associated with major congenital heart disease. The aetiology and mechanisms underlying most cases of human heterotaxy are poorly understood. In vertebrates, laterality is initiated at the embryonic left–right organizer, where motile cilia generate leftward flow that is detected by immotile sensory cilia, which transduce flow into downstream asymmetric signals. The mechanism that specifies these two cilia types remains unknown. Here we show that the N-acetylgalactosamine-type O-glycosylation enzyme GALNT11 is crucial to such determination. We previously identified GALNT11 as a candidate disease gene in a patient with heterotaxy, and now demonstrate, in Xenopus tropicalis, that galnt11 activates Notch signalling. GALNT11 O-glycosylates human NOTCH1 peptides in vitro, thereby supporting a mechanism of Notch activation either by increasing ADAM17-mediated ectodomain shedding of the Notch receptor or by modification of specific EGF repeats. We further developed a quantitative live imaging technique for Xenopus left–right organizer cilia and show that Galnt11-mediated Notch1 signalling modulates the spatial distribution and ratio of motile and immotile cilia at the left–right organizer. galnt11 or notch1 depletion increases the ratio of motile cilia at the expense of immotile cilia and produces a laterality defect reminiscent of loss of the ciliary sensor Pkd2. By contrast, Notch overexpression decreases this ratio, mimicking the ciliopathy primary ciliary dyskinesia. Together our data demonstrate that Galnt11 modifies Notch, establishing an essential balance between motile and immotile cilia at the left–right organizer to determine laterality, and reveal a novel mechanism for human heterotaxy.

Minimally invasive aortic valve replacement versus aortic valve replacement through full sternotomy: the Brigham and Women’s Hospital experience

BACKGROUND Minimally invasive aortic valve surgery (mini AVR) is a safe and effective treatment option at many hospital centers, but there has not been widespread adoption of the procedure. Critics of mini AVR have called for additional evidence with direct comparison to aortic valve replacement (AVR) via full sternotomy (FS). METHODS Our mini AVR approach is through a hemi-sternotomy (HS). We performed a propensity-score matched analysis of all patients undergoing isolated AVR via FS or HS at our institution since 2002, resulting in 552 matched pairs. Baseline characteristics were similar. Operative characteristics, transfusion rates, in-hospital outcomes as well as short and long term survival were compared between groups. RESULTS Median cardiopulmonary bypass and cross clamp times were shorter in the HS group: 106 minutes [inter-quartile ranges (IQR) 87-135] vs. 124 minutes (IQR 90-169), P≤0.001, and 76 minutes (IQR 63-97) vs. 80 minutes (IQR 62-114), P≤0.005, respectively. HS patients had shorter ventilation times (median 5.7 hours, IQR 3.5-10.3 vs. 6.3 hours, IQR 3.9-11.2, P≤0.022), shorter intensive care unit stay (median 42 hours, IQR 24-71 vs. 45 hours, IQR 24-87, P≤0.039), and shorter hospital length of stay (median 6 days, IQR 5-8 vs. 7 days, IQR 5-10, P≤0.001) compared with the FS group. Intraoperative transfusions were more common in FS group: 27.9% vs. 20.0%, P≤0.003. No differences were seen in short or long term survival, or time to aortic valve re-intervention. CONCLUSIONS Our study confirms the clinical benefits of minimally invasive AVR via HS, which includes decreased transfusion requirements, ventilation times, intensive care unit and hospital length of stay without compromising short and long term survival compared to conventional AVR via FS.

TRANSMITRAL FLOW VELOCITY-CONTOUR VARIATION AFTER PREMATURE VENTRICULAR CONTRACTIONS: A NOVEL TEST OF THE LOAD-INDEPENDENT INDEX OF DIASTOLIC FILLING

The new echocardiography-based, load-independent index of diastolic filling (LIIDF) M was assessed using load-/shape-varying E-waves after premature ventricular contractions (PVCs). Twenty-six PVCs in 15 subjects from a preexisting simultaneous echocardiography-catheterization database were selected. Perturbed load-state beats, defined as the first two post-PVC E-waves, and steady-state E-waves, were subjected to conventional and model-based analysis. M, a dimensionless index, defined by the slope of the peak driving-force vs. peak (filling-opposing) resistive-force regression, was determined from steady-state E-waves alone, and from load-perturbed E-waves combined with a matched number of subsequent beats. Despite high degrees of E-wave shape variation, M derived from load-varying, perturbed beats and M derived from steady-state beats alone were indistinguishable. Because the peak driving-force vs. peak resistive-force relation determining M remains highly linear in the extended E-wave shape and load variation regime observed, we conclude that M is a robust LIIDF.

Lymphangioma of the Gallbladder in Adults: Review of the Literature and a Case Report

IntroductionLymphangiomas of the gallbladder in adults are extremely rare with only 10 cases published worldwide to date.Case PresentationWe herein report a case of a 26-year-old male who presented with abdominal right upper quadrant pain, nausea, vomiting, and diarrhea. An ultrasound, computer tomography scan, and magnetic resonance imaging showed a cystic mass interposed between the gallbladder and the liver with characteristics identical to those of lymphangiomas in more common locations. The patient underwent an open excision of the large spongy mass en bloc with the gallbladder.ConclusionHistological findings confirmed the diagnosis of lymphangioma. Also, we provide a review of 10 cases presented in the literature, with a discussion of the clinical features, diagnosis, and surgical approach.

Robust identification of deletions in exome and genome sequence data based on clustering of Mendelian errors

Multiple tools have been developed to identify copy number variants (CNVs) from whole exome (WES) and whole genome sequencing (WGS) data. Current tools such as XHMM for WES and CNVnator for WGS identify CNVs based on changes in read depth. For WGS, other methods to identify CNVs include utilizing discordant read pairs and split reads and genome‐wide local assembly with tools such as Lumpy and SvABA, respectively. Here, we introduce a new method to identify deletion CNVs from WES and WGS trio data based on the clustering of Mendelian errors (MEs). Using our Mendelian Error Method (MEM), we identified 127 deletions (inherited and de novo) in 2,601 WES trios from the Pediatric Cardiac Genomics Consortium, with a validation rate of 88% by digital droplet PCR. MEM identified additional de novo deletions compared with XHMM, and a significant enrichment of 15q11.2 deletions compared with controls. In addition, MEM identified eight cases of uniparental disomy, sample switches, and DNA contamination. We applied MEM to WGS data from the Genome In A Bottle Ashkenazi trio and identified deletions with 97% specificity. MEM provides a robust, computationally inexpensive method for identifying deletions, and an orthogonal approach for verifying deletions called by other tools.