SARS-CoV-2 Serosurveys: How Antigen, Isotype and Threshold Choices Affect the Outcome.

BACKGROUND: Evaluating the performance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serological assays and clearly articulating the utility of selected antigens, isotypes, and thresholds is crucial to understanding the prevalence of infection within selected communities. METHODS: This cross-sectional study, implemented in 2020, screened PCRconfirmed coronavirus disease 2019 patients (n 86), banked prepandemic and negative samples (n 96), healthcare workers and family members (n 552), and university employees (n 327) for antiSARS-CoV-2 receptor-binding domain, trimeric spike protein, and nucleocapsid protein immunoglobulin (Ig)G and IgA antibodies with a laboratory-developed enzyme-linked immunosorbent assay and tested how antigen, isotype and threshold choices affected the seroprevalence outcomes. The following threshold methods were evaluated: (i) mean 3 standard deviations of the negative controls; (ii) 100 specificity for each antigen-isotype combination; and (iii) the maximal Youden index. RESULTS: We found vastly different seroprevalence estimates depending on selected antigens and isotypes and the applied threshold method, ranging from 0.0 to 85.4. Subsequently, we maximized specificity and reported a seroprevalence, based on more than one antigen, ranging from 9.3 to 25.9. CONCLUSIONS: This study revealed the importance of evaluating serosurvey tools for antigen-, isotype-, and threshold-specific sensitivity and specificity, to interpret qualitative serosurvey outcomes reliably and consistently across studies.

Retinal detachment in Loeys-Dietz syndrome.

Loeys-Dietz syndrome (LDS) is an autosomal-dominant connective-tissue disorder with vascular and musculoskeletal abnormalities similar to Marfan syndrome. However, unlike Marfan, retinal detachment (RD) is rarely reported, and screening protocols do not currently feature ophthalmic assessment or RD counseling. We report a 5-generation family affected by LDS, where RD occurred in six eyes of four individuals. The proband was an 84-year-old male recently diagnosed with type-V LDS (TGFß3 pathogenic variant c.899G>A, p.(Arg300Gln)). Further investigation was undertaken into the family's medical history. The proband experienced bilateral rhegmatogenous RD at age 60, requiring emergency surgical repair. Other notable ophthalmic features include unusual keratometry, abnormal biometry, and severe hayfever requiring long-term sodium cromoglycate treatment. The proband's sister, father, and uncle had also experienced RDs, all prior to LDS diagnosis. This series demonstrates that RD risk may be significant in LDS, and on occasion the presenting clinical feature. We suggest ophthalmic examination should be added to the initial assessment LDS patients, and patients informed of the early warning symptoms of retinal detachment. As in Marfan syndrome, LDS patients may exhibit cornea plana and abnormal corneal topography, producing atypical biometry. They may also present with allergic conjunctivitis, and awareness of these signs might facilitate earlier diagnosis.

Comparison of 30 Day Stroke and Death in Hybrid Intervention and Open Surgical Reconstruction for the Treatment of Tandem Carotid Bifurcation and Supra-aortic Trunk Disease.

OBJECTIVE: The optimal approach for the treatment of tandem carotid bifurcation and supra-aortic trunk (SAT) disease remains controversial. The hybrid technique of carotid endarterectomy (CEA) with ipsilateral proximal endovascular intervention (IPE) has provided an attractive alternative to CEA with open SAT reconstruction (SATr). However, no studies have compared cohorts treated by these two approaches. METHODS: Using the National Surgical Quality Improvement Program (2005-2017), patients who underwent CEA + IPE and CEA + SATr were identified. Non-occlusive indications were excluded. Primary outcomes included 30 day stroke, death, and their composite (stroke and/or death [SD]). Univariable and logistic regression analyses were performed. RESULTS: In total, 372 patients were identified: 319 CEA + SATr and 53 CEA + IPE. SATr included 19 (5.9%) aorta to carotid bypasses, 22 (6.9%) carotid subclavian transpositions, 96 (30.1%) carotid carotid bypasses, 179 (56.1%) carotid subclavian bypasses, and three (0.9%) SAT endarterectomies. The mean age was 69 ± 10 years. The majority were men (53%), white (85%), and had a history of hypertension (84%). There were no demographic differences between the operative cohorts except that those having CEA + SATr were more likely to have hypertension (86% vs. 74%; p = .031). CEA + SATr had longer operative times and longer hospital length of stay. There were no differences in outcomes between the cohorts: stroke (CEA + SATr 4.1% vs. CEA + IPE 3.8%; p = .92), death (1.6% vs. 0%; p = .36), or SD (5.3% vs. 3.8%; p = .63). After risk adjustment, predictors of SD included symptomatic status (odds ratio [OR] 3.9, 95% confidence interval [CI] 1.1-13.5; p = .034), congestive heart failure (OR 16.5, 95% CI 2.0-136; p = .011), and return to the operating room (OR 8.5, 95% CI 2.3-30.8; p = .001). Operative method was not predictive (p = .63). CONCLUSION: Outcomes following CEA + SATr and CEA + IPE are similar. Although proposed as a safer, less invasive alternative, the hybrid approach did not reduce the risk of operative stroke or death relative to open reconstruction for the treatment of occlusive, tandem carotid/SAT disease. Based upon lesion and patient factors, both may be considered management options in select patients.

Impact of Adding Carotid Endarterectomy to Supra-aortic Trunk Surgical Reconstruction.

BACKGROUND: Up to 20% of patients requiring open supra-aortic trunk (SAT) reconstruction have significant carotid artery stenosis. The addition of carotid endarterectomy (CEA) to SAT has been described. Yet, additive risks are not well defined and controversy remains as to whether concomitant CEA increases stroke risk. This study assessed the perioperative effects of adding CEA to SAT. METHODS: Using the National Surgical Quality Improvement Program (NSQIP), patients who underwent SAT from 2005 to 2015 were evaluated. SAT + CEA were identified. An isolated SAT (ISAT) cohort was created by removing patients who underwent concurrent secondary procedures. Nonocclusive indications were excluded. SAT + CEA were compared with ISAT as well as a propensity-matched ISAT cohort. Primary outcomes were 30-day stroke, death, and composite stroke/death/myocardial infarction (SDM). Univariate and logistic regression analyses were performed. RESULTS: After review, 1,515 patients were identified: 1,245 ISAT (82%) and 270 SAT + CEA (18%). Most were women (56%), 86% were Caucasian, and 24% were symptomatic. Average age was 65 ± 12 years and SAT + CEA were older (69 vs. 64 years, P < 0.001). CEA + SAT were more likely to be men (53% vs. 42%, P < 0.001), have hypertension (86% vs. 75%, P < 0.001) and diabetes (26% vs. 20%, P = 0.04). SAT procedures included the following: carotid-subclavian bypass (68%), carotid-carotid bypass (16%), aorta-great vessel bypass (9%), and carotid-subclavian transposition (7%). ISAT were more likely to undergo carotid-subclavian bypass than SAT + CEA (71% vs. 54%, P < 0.001). Overall stroke was 2.3%, death 1.4%, and SDM 4.6%. There were no differences in 30-day stroke (ISAT 2.0% vs. SAT + CEA 3.7%, P = 0.09) or mortality (1.4% vs. 1.5%, P = 0.88). SAT + CEA had higher rates of SDM (7% vs. 4%, P = 0.03). On logistic regression, urgency was a predictor of SDM (operating room [OR] 3.6, 95% confidence interval [CI] 1.5-8.4, P = 0.003); addition of CEA was not predictive of stroke (OR 1.4, 95% CI 0.5-4.2, P = 0.52) or SDM (OR 1.5, 95% CI 0.6-3.6, P = 0.40). After propensity matching, there were no longer differences in demographics or primary end points between the 2 cohorts. CONCLUSIONS: Addition of CEA does not confer increased perioperative stroke or SDM risk over ISAT. Perioperative outcomes appear to be more affected by disseminated disease risk factors than the addition of CEA. In patients undergoing SAT, it is reasonable to consider performing combined CEA in populations with tandem carotid bifurcation disease and appropriate operative risk profile.

Homozygous Type IX collagen variants (COL9A1, COL9A2, and COL9A3) causing recessive Stickler syndrome-Expanding the phenotype.

Stickler syndrome (SS) is characterized by ophthalmic, articular, orofacial, and auditory manifestations. SS is usually autosomal dominantly inherited with variants in COL2A1 or COL11A1. Recessive forms are rare but have been described with homozygous variants in COL9A1, COL9A2, and COL9A3 and compound heterozygous COL11A1 variants. This article expands phenotypic descriptions in recessive SS due to variants in genes encoding Type IX collagen. Clinical features were assessed in four families. Genomic DNA samples derived from venous blood were collected from family members. Six affected patients were identified from four pedigrees with variants in COL9A1 (one family, one patient), COL9A2 (two families, three patients), and COL9A3 (one family, two patients). Three variants were novel. All patients were highly myopic with congenital megalophthalmos and abnormal, hypoplastic vitreous gel, and all had sensorineural hearing loss. One patient had severe arthropathy. Congenital megalophthalmos and myopia are common to dominant and recessive forms of SS. Sensorineural hearing loss is more common and severe in recessive SS. We suggest that COL9A1, COL9A2, and COL9A3 be added to genetic screening panels for patients with congenital hearing loss. Although recessive SS is rare, early diagnosis would have a high impact for children with potentially dual sensory impairment, as well as identifying risk to future children.

Posterior vitreous detachment and retinal tear - a prospective study of community referrals.

BACKGROUND: Retinal tears (RT) from posterior vitreous detachment (PVD) are an important and treatable cause of rhegmatogenous retinal detachment (RRD). Better understanding of the risk of RT from PVD will help plan urgent eye care. METHODS: Prospective observational case series over two years. Patients presenting to their optometrist, family doctor or emergency department with flashes and floaters were directed to a research clinic. History and examination, including slit-lamp biomicroscopy (SLB) and indentation indirect ophthalmoscopy (IIO), were performed by a single investigator, with two month follow-up for patients with confirmed PVD. Main outcome measures were incidence of PVD, RT, and RRD. RESULTS: 1010 patients were recruited. 896 (89%) patients had PVD at first assessment, of which 89 (8.8% of total cohort, 9.9% of PVD eyes) had RT and 8 had RRD. 21 (3%) of the remaining PVD patients developed RT in the subsequent two months and a further 9 (11%) patients with RT at initial assessment developed further tears by two months. 7 (0.7%) had asymptomatic RT in the fellow eye. 15% of RT were only visible on IIO and not SLB. Weiss ring was absent in 32% of eyes with RT. Patients with RT or RRD were more likely than 'PVD-only' eyes to have blurred or missing vision (p < 0.001), have higher rate of blue-green cataracts (p < 0.001), and longer axial lengths (p < 0.05). CONCLUSIONS AND RELEVANCE: This large, prospective study demonstrates a 9.9% rate of RT or RRD at the time of PVD, and emphasises the importance of IIO examination.

Use of vitreous phenotype as a key clinical marker to identify Ocular-only Stickler syndrome in a family with Marfan syndrome.

This clinical report describes a family with both Marfan and ocular-only Stickler syndromes. We report 2 cases of ocular-only Stickler syndrome and 2 cases of Marfan syndrome concurrent with ocular-only Stickler syndrome. Type 1 Stickler syndrome and Marfan syndrome share many clinical similarities, and it can be difficult to differentiate them solely based on clinical presentation. Vitreous phenotyping allows for the identification of vitreous anomalies pathognomonic of Stickler syndrome, which can guide future gene sequencing. Having the accurate diagnosis of Marfan or type 1 Stickler syndrome is important, as patients with type 1 Stickler syndrome have higher rates of retinal detachment and will benefit from prophylaxis.

Peripapillary Hyperreflective Ovoid Mass-Like Structures in Stickler Syndrome.

PURPOSE: To report a previously undescribed finding of peripapillary hyperreflective ovoid mass-like structures (PHOMS) in Stickler syndrome. DESIGN: Noncomparative case series. SUBJECTS: Twenty-two eyes with anomalous optic disc from 11 Stickler syndrome patients were identified and imaged. METHODS: Peripapillary hyperreflective ovoid mass-like structures were graded using enhanced-depth imaging OCT (EDI-OCT) according to the consensus recommendations of the Optic Disc Drusen Studies Consortium. All EDI-OCT scans were obtained using the Heidelberg Spectralis (Heidelberg Engineering) with a dense horizontal raster (15 × 10°, 97 sections) centered on the optic nerve head and graded by 2 independent assessors. In case of disagreement, the image was graded by a third assessor. The presence of any coexisting optic disc drusen was also assessed using EDI-OCT and autofluorescence. MAIN OUTCOME MEASURES: The presence of PHOMS, clinical characteristics and genetic mutations. RESULTS: A pilot sample of 22 eyes with phenotypic optic disc abnormalities from 11 Stickler syndrome patients were identified and imaged. Eight patients were female and 3 were male. The mean age was 31 years (13-58 years). Peripapillary hyperreflective ovoid mass-like structures were present in 91% (n = 20) of imaged eyes. Seventy percent (n = 14) were type 1 Stickler syndrome and 30% (n = 6) were type 2 Stickler syndrome. All eyes were myopic and the degree of myopia did not seem to affect whether or not PHOMS was present in this cohort. One eye with PHOMS had retinal detachment, and 77.3% (n = 17) of eyes had undergone 360o prophylactic retinopexy. Thirty-two percent (n = 7) of eyes with PHOMS were present in patients with coexisting hearing loss and 22.7% (n = 5) had orofacial manifestation of Stickler syndrome in the form of a cleft palate. Seventy-seven percent (n = 15) of eyes with PHOMS were present in patients who reported joint laxity or symptoms of arthritis. No coexisting optic disc drusen were identified and raised intracranial pressure was also excluded after neurological investigation. CONCLUSIONS: These data suggest that PHOMS are a novel finding in Stickler syndrome patients and should be considered when evaluating the optic nerves of these patients. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Legg-Calve-Perthes' disease: an opportunity to prevent blindness?

Legg-Calve-Perthes' disease (LCP) is defined as avascular necrosis of the femoral head in a child and may present to a variety of disciplines from general practice to orthopaedics, paediatrics, rheumatology and more. The Stickler syndromes are a group of disorders of type II, IX and XI collagen associated with hip dysplasia, retinal detachment, deafness and cleft palate. The pathogenesis of LCP disease remains an enigma but there have been a small number of cases reporting variants in the gene encoding the α1 chain of type II collagen (COL2A1). Variants in COL2A1 are known to cause type 1 Stickler syndrome (MIM 108300, 609508), which is a connective tissue disorder with a very high risk of childhood blindness, and it is also associated with dysplastic development of the femoral head. It is unclear whether COL2A1 variants make a definitive contribution to both disorders, or whether the two are indistinguishable using current clinical diagnostic techniques. In this paper, we compare the two conditions and present a case series of 19 patients with genetically confirmed type 1 Stickler syndrome presenting with a historic diagnosis of LCP. In contrast to isolated LCP, children with type 1 Stickler syndrome have a very high risk of blindness from giant retinal tear detachment, but this is now largely preventable if a timely diagnosis is made. This paper highlights the potential for avoidable blindness in children presenting to clinicians with features suggestive of LCP disease but with underlying Stickler syndrome and proposes a simple scoring system to assist clinicians.

Autosomal Recessive Stickler Syndrome.

Stickler syndrome (SS) is a genetic disorder with manifestations in the eye, ear, joints, face and palate. Usually inherited in a dominant fashion due to heterozygous pathogenic variants in the collagen genes COL2A1 and COL11A1, it can rarely be inherited in a recessive fashion from variants in COL9A1, COL9A2, and COL9A3, COL11A1, as well as the non-collagen genes LRP2, LOXL3 and GZF1. We review the published cases of recessive SS, which comprise 40 patients from 23 families. Both homozygous and compound heterozygous pathogenic variants are found. High myopia is near-universal, and sensorineural hearing loss is very common in patients with variants in genes for type IX or XI collagen, although hearing appears spared in the LRP2 and LOXL3 patients and is variable in GZF1. Cleft palate is associated with type XI collagen variants, as well as the non-collagen genes, but is so far unreported with type IX collagen variants. Retinal detachment has occurred in 18% of all cases, and joint pain in 15%. However, the mean age of this cohort is 11 years old, so the lifetime incidence of both problems may be underestimated. This paper reinforces the importance of screening for SS in congenital sensorineural hearing loss, particularly when associated with myopia, and the need to warn patients and parents of the warning signs of retinal detachment, with regular ophthalmic review.

Modulating immune responses to AAV by expanded polyclonal T-regs and capsid specific chimeric antigen receptor T-regulatory cells.

Immune responses to adeno-associated virus (AAV) capsids limit the therapeutic potential of AAV gene therapy. Herein, we model clinical immune responses by generating AAV capsid-specific chimeric antigen receptor (AAV-CAR) T cells. We then modulate immune responses to AAV capsid with AAV-CAR regulatory T cells (Tregs). AAV-CAR Tregs in vitro display phenotypical Treg surface marker expression, and functional suppression of effector T cell proliferation and cytotoxicity. In mouse models, AAV-CAR Tregs mediated continued transgene expression from an immunogenic capsid, despite antibody responses, produced immunosuppressive cytokines, and decreased tissue inflammation. AAV-CAR Tregs are also able to bystander suppress immune responses to immunogenic transgenes similarly mediating continued transgene expression, producing immunosuppressive cytokines, and reducing tissue infiltration. Taken together, AAV-CAR T cells and AAV-CAR Tregs are directed and powerful immunosuppressive tools to model and modulate immune responses to AAV capsids and transgenes in the local environment.

Novel Combinatorial MicroRNA-Binding Sites in AAV Vectors Synergistically Diminish Antigen Presentation and Transgene Immunity for Efficient and Stable Transduction.

Recombinant adeno-associated virus (rAAV) platforms hold promise for in vivo gene therapy but are undermined by the undesirable transduction of antigen presenting cells (APCs), which in turn can trigger host immunity towards rAAV-expressed transgene products. In light of recent adverse events in patients receiving high systemic AAV vector doses that were speculated to be related to host immune responses, development of strategies to mute innate and adaptive immunity is imperative. The use of miRNA binding sites (miR-BSs) to confer endogenous miRNA-mediated regulation to detarget transgene expression from APCs has shown promise for reducing transgene immunity. Studies have shown that designing miR-142BSs into rAAV1 vectors were able to repress costimulatory signals in dendritic cells (DCs), blunt the cytotoxic T cell response, and attenuate clearance of transduced muscle cells in mice to allow sustained transgene expression in myofibers with negligible anti-transgene IgG production. In this study, we screened individual and combinatorial miR-BS designs against 26 miRNAs that are abundantly expressed in APCs, but not in skeletal muscle. The highly immunogenic ovalbumin (OVA) transgene was used as a proxy for foreign antigens. In vitro screening in myoblasts, mouse DCs, and macrophages revealed that the combination of miR-142BS and miR-652-5pBS strongly mutes transgene expression in APCs but maintains high myoblast and myocyte expression. Importantly, rAAV1 vectors carrying this novel miR-142/652-5pBS cassette achieve higher transgene levels following intramuscular injections in mice than previous detargeting designs. The cassette strongly inhibits cytotoxic CTL activation and suppresses the Th17 response in vivo. Our approach, thus, advances the efficiency of miRNA-mediated detargeting to achieve synergistic reduction of transgene-specific immune responses and the development of safe and efficient delivery vehicles for gene therapy.

Inferior petrosal sinus ACTH and prolactin responses to CRH in ACTH-dependent Cushing's syndrome: a single centre experience from the United Kingdom.

Inferior petrosal sinus sampling (IPSS) of ACTH with CRH stimulation helps distinguish pituitary ACTH-dependent Cushing's syndrome from the ectopic ACTH syndrome (EAS). The usefulness of the paradoxical response of other pituitary hormones including prolactin to CRH remains controversial. Data from 33 IPSS procedures carried out at the Walton Centre for Neurology and Neurosurgery in Liverpool were analyzed. Patients were selected for this procedure if they had been diagnosed with ACTH dependent Cushing's syndrome and the majority had no obvious pituitary adenoma on Magnetic Resonance Imaging. Satisfactory simultaneous bilateral catheterization was accomplished in 23/33 (success rate 70%). The diagnostic sensitivity of a basal central/peripheral ACTH ratio >2.0 and >3 post-CRH was 94%. In two patients with subsequently confirmed EAS the maximal central/peripheral ACTH ratio was <2.0 on basal samples and did not change following CRH. The maximal central/peripheral prolactin ratio was noted at 5 min post-CRH, coinciding with the maximal central/peripheral ACTH ratio. The intersinus gradient (ISG) of ACTH was paralleled by a consistent ISG of prolactin and in 7 out of 9 patients (with successful bilateral IPSS and unilateral adenomas) the ISG of prolactin correctly lateralized the microadenoma whereas the ISG of ACTH correctly lateralized in 8 out of 9 patients. Neither of the patients with EAS achieved a central/peripheral prolactin ratio >2 in the basal state and >3 post-CRH. Bilateral catheterization of inferior petrosal sinuses can be successful in up to 70% of cases. Prolactin measurements do not have superior lateralizing capability compared with ACTH but may be useful in the differential diagnosis of pituitary-driven from EAS.

Inherited and de novo biallelic pathogenic variants in COL11A1 result in type 2 Stickler syndrome with severe hearing loss.

BACKGROUND: Type 2 Stickler syndrome is usually a dominant disorder resulting from pathogenic variants in COL11A1 encoding the alpha 1 chain of type XI collagen. Typical molecular changes result in either substitution of an obligate glycine within the Gly-Xaa-Yaa amino acid sequence repeat region of the molecule, mRNA missplicing or deletions/duplications that typically leaves the message in-frame. Clinical features include myopia, retinal detachment, craniofacial, joint, and hearing problems. Fibrochondrogenesis is also a COL11A1 related disorder, but here disease-associated variants are recessive and may be either null alleles or substitutions of glycine, and the condition is usually lethal in infancy. METHODS: The patient was assessed in the NHS England Stickler syndrome diagnostic service. DNA from the patient and family were analyzed with Next Generation Sequencing on a panel of genes known to cause Stickler Syndrome. The effect of sequence variants was assessed using minigene analysis. Allele-specific RT-PCR was performed. RESULTS: This patient had clinical type 2 Stickler syndrome but with severe hearing loss and severe ocular features including retinal atrophy and retinal tears in childhood. We identified a de novo in frame deletion of COL11A1 (c.4109_4126del) consistent with dominantly inherited Stickler syndrome but also a second inherited variant (c.1245+2T>C), on the other allele, affecting normal splicing of COL11A1 exon 9. CONCLUSION: Exon 9 of COL11A1 is alternatively expressed and disease causing changes affecting only this exon modify the phenotype resulting from biallelic COL11A1 disease-associated variants and, instead of fibrochondrogenesis, produce a form of Stickler syndrome with severe hearing loss. Disease phenotypes from de novo pathogenic variants can be modified by inherited recessive variants on the other allele. This highlights the need for functional and family analysis to confirm the mode of inheritance in COL11A1-related disorders, particularly for those variants that may alter normal pre-mRNA splicing.

Feasibility of simple machine learning approaches to support detection of non-glaucomatous visual fields in future automated glaucoma clinics.

OBJECTIVES: To assess the performance of feed-forward back-propagation artificial neural networks (ANNs) in detecting field defects caused by pituitary disease from among a glaucomatous population. METHODS: 24-2 Humphrey Visual Field reports were gathered from 121 pituitary patients and 907 glaucomatous patients. Optical character recognition was used to extract the threshold values from PDF reports. Left and right eye visual fields were coupled for each patient in an array to create bilateral field representations. ANNs were created to detect chiasmal field defects. We also assessed the ability of ANNs to identify a single pituitary field among 907 glaucomatous distractors. RESULTS: Mean field thresholds across all locations were lower for pituitary patients (20.3 dB, SD = 5.2 dB) than for glaucoma patients (24.4 dB, SD = 5.0 dB) indicating a greater degree of field loss (p < 0.0001) in the pituitary group. However, substantial overlap between the groups meant that mean bilateral field loss was not a reliable indicator of aetiology. Representative ANNs showed good performance in the discrimination task with sensitivity and specificity routinely above 95%. Where a single pituitary field was hidden among 907 glaucomatous fields, it had one of the five highest indexes of suspicion on 91% of 2420 ANNs. CONCLUSIONS: Traditional artificial neural networks perform well at detecting chiasmal field defects among a glaucoma cohort by inspecting bilateral field representations. Increasing automation of care means we will need robust methods of automatically diagnosing and managing disease. This work shows that machine learning can perform a useful role in diagnostic oversight in highly automated glaucoma clinics, enhancing patient safety.

Bone morphogenetic protein 4 (BMP4) loss-of-function variant associated with autosomal dominant Stickler syndrome and renal dysplasia.

Stickler syndrome is a genetic disorder that can lead to joint problems, hearing difficulties and retinal detachment. Genes encoding collagen types II, IX and XI are usually responsible, but some families have no causal variant identified. We investigate a variant in the gene encoding growth factor BMP4 in a family with Stickler syndrome with associated renal dysplasia. Next generation sequencing of the coding region of COL2A1, COL11A1 and a panel of genes associated with congenital anomalies of the kidney and urinary tract (CAKUT) was performed. A novel heterozygous BMP4 variant causing a premature stop codon, c. 130G>T, p.(Gly44Ter), which segregated with clinical features of Stickler syndrome in multiple family members, was identified. No variant affecting gene function was detected in COL2A1 or COL11A1. Skin fibroblasts were cultured with and without emetine, and the mRNA extracted and analysed by Sanger sequencing to assess whether the change was causing nonsense-mediated decay. Nonsense-mediated decay was not observed from the extracted BMP4 mRNA. BMP4 is a growth factor known to contribute to eye development in animals, and gene variants in humans have been linked to microphthalmia/anophthalmia as well as CAKUT. The variant identified here further demonstrates the importance of BMP4 in eye development. This is the first report of a BMP4 DNA variant causing Stickler syndrome, and we suggest BMP4 be added to standard diagnostic gene panels for this condition.

Upper airway collapsibility and genioglossus activity in adolescents during sleep.

STUDY OBJECTIVES: Obese patients develop obstructive sleep apnea syndrome (OSAS), at least in part because of a narrowed upper airway. However, many obese adolescents do not develop OSAS, despite having a presumably narrower airway. The reasons for this phenomenon are unclear. The authors hypothesized that obese controls have a compensatory neuromuscular response to subatmospheric pressure loads during sleep, making them less likely to develop upper airway collapse. DESIGN: Patients underwent pressure-flow measurements during sleep while wearing intraoral electrodes to measure genioglossal electromyography (EMGgg). Two techniques were applied to decrease nasal pressure (P(N)) to subatmospheric levels, resulting in an activated and relatively hypotonic upper airway. SETTING: Sleep laboratory. PARTICIPANTS: There were 35 obese patients with OSAS, 28 obese controls, and 43 lean controls. RESULTS: In the activated state, the two control groups had a flatter slope of the pressure-flow relationship and a more negative critical closing pressure (less collapsible) than the OSAS group. In the hypotonic state, the lean controls had a flatter slope of the pressure-flow relationship than the OSAS and obese control groups. In the activated state, the slope of EMGgg versus P(N) was greater in the obese control group than in the OSAS or lean control groups (P = 0.002 and P = 0.028, respectively); there were no differences in the hypotonic state. CONCLUSIONS: Obese controls have vigorous upper airway neuromuscular responses during sleep. Upper airway reflexes normally decline during adolescent development. It is speculated that obese adolescents without OSAS maintain protective upper airway reflexes during adolescent development, whereas those who go on to develop OSAS do not.