Mutations causing premature termination codons discriminate and generate cellular and clinical variability in HHT.

ABSTRACT: For monogenic diseases caused by pathogenic loss-of-function DNA variants, attention focuses on dysregulated gene-specific pathways, usually considering molecular subtypes together within causal genes. To better understand phenotypic variability in hereditary hemorrhagic telangiectasia (HHT), we subcategorized pathogenic DNA variants in ENG/endoglin, ACVRL1/ALK1, and SMAD4 if they generated premature termination codons (PTCs) subject to nonsense-mediated decay. In 3 patient cohorts, a PTC-based classification system explained some previously puzzling hemorrhage variability. In blood outgrowth endothelial cells (BOECs) derived from patients with ACVRL1+/PTC, ENG+/PTC, and SMAD4+/PTC genotypes, PTC-containing RNA transcripts persisted at low levels (8%-23% expected, varying between replicate cultures); genes differentially expressed to Bonferroni P < .05 in HHT+/PTC BOECs clustered significantly only to generic protein terms (isopeptide-bond/ubiquitin-like conjugation) and pulse-chase experiments detected subtle protein maturation differences but no evidence for PTC-truncated protein. BOECs displaying highest PTC persistence were discriminated in unsupervised hierarchical clustering of near-invariant housekeeper genes, with patterns compatible with higher cellular stress in BOECs with >11% PTC persistence. To test directionality, we used a HeLa reporter system to detect induction of activating transcription factor 4 (ATF4), which controls expression of stress-adaptive genes, and showed that ENG Q436X but not ENG R93X directly induced ATF4. AlphaFold accurately modeled relevant ENG domains, with AlphaMissense suggesting that readthrough substitutions would be benign for ENG R93X and other less rare ENG nonsense variants but more damaging for Q436X. We conclude that PTCs should be distinguished from other loss-of-function variants, PTC transcript levels increase in stressed cells, and readthrough proteins and mechanisms provide promising research avenues.

Outcome of endoscopic sphenopalatine artery occlusion for intractable epistaxis: a 10-year experience.

OBJECTIVE/HYPOTHESIS: To evaluate the efficacy of surgical sphenopalatine artery occlusion (SAO) for treating intractable epistaxis, and identify factors associated with long-term success or failure of this procedure. METHODS: A retrospective chart review of patients undergoing SAO surgery between January 1995 and 2005 was undertaken. Clinical and hematologic information, preoperative and surgical care, short-term complications, and long-term outcome were recorded. Binary logistic regression was used to identify risk factors for early re-bleeding, and log-rank statistics with Cox regression were used to identify risk factors for long-term operative failure. RESULTS: Sixty-seven patients underwent 71 SAO operations. The average age at surgery was 56 +/- 18 years. Thirty percent of patients were being treated for hypertension, 19% were taking aspirin, and 11% were anticoagulated with warfarin. Many patients (46%) had >72 hours of epistaxis before admission, and 25% required preoperative transfusion. There were 13 (19%) bilateral procedures, six patients underwent concomitant anterior ethmoid artery occlusion, and 12 patients had concomitant septoplasty. Eight patients had significant early re-bleeding. Platelet levels on admission and not using diathermy to occlude the sphenopalatine artery were independent risk factors for this (P values .03, and .02, respectively). Not using diathermy was also an independent risk factor for late operative failure on Cox regression, reducing the mean re-intervention-free interval from 94 +/- 7 to 32 +/- 7 months (P < .007; hazard ratio 6.4; 95% confidence interval 1.7-24.9). CONCLUSIONS: SAO is an effective operation and, in trained hands, an appropriate first-line procedure for treating intractable epistaxis. Use of diathermy significantly improves the short- and long-term outcome of this surgery.

Functional endoscopic sinus surgery: 5 year follow up and results of a prospective, randomised, stratified, double-blind, placebo controlled study of postoperative fluticasone propionate aqueous nasal spray.

One hundred nine patients with chronic rhinosinusitis underwent functional endoscopic sinus surgery. Seventy seven patients had polyposis. The population was studied prospectively for 5 years postoperatively. Seventy two patients attended the 5 year follow-up visit. At 1, 2, 3, 4 and 5 years of follow-up all outcome measures except olfactory detection thresholds (visual analogue scores, endoscopic findings, nasal mucociliary clearance times, total nasal volumes) were significantly improved compared to preoperative baseline values. Olfactory detection thresholds were significantly improved at 1 and 2 years postoperation. Patient symptom scores were improved in a greater percentage of patients than more objective outcome measures. Thirty eight patients required a total of 88 postoperative rescue medication courses with prednisolone and antibiotic. Twelve patients failed the study as they required at least 1 rescue medication course a month for 2 consecutive months. We demonstrated an 89% 5 year "survival" rate with regards to the risk of failure. The patients were also entered into a randomised, stratified, prospective, double-blind, placebo controlled study of fluticasone propionate aqueous nasal spray 200 mcg twice daily, commencing 6 weeks after FESS, with a 5 year follow-up. The change in overall visual analogue score was significantly better in the FPANS group at 5 years. The changes in endoscopic oedema and polyp scores and in total nasal volumes were significantly better in the FPANS group at 4 years but not 5 years. Last value carried forward analysis demonstrated that changes in endoscopic polyp score and in total nasal volume was significantly better in the FPANS group at 5 years. Significantly more prednisolone rescue medication courses were prescribed in the placebo group. Of the 12 patients who failed the study, 10 were in the placebo group. This difference nearly achieved significance.