Novel heterozygous PRPH2 variant identified in a patient with spinocerebellar ataxia type 14 and macular dystrophy

PURPOSE

To report on a patient with spinocerebellar ataxia type 14 (SCA14) and macular dystrophy with identification of a novel PRPH2 variant.

METHODS

Case report.

RESULTS

A 63-year-old female with molecularly confirmed SCA14 presented with symmetric pigmentary disturbances in a perifoveal distribution resembling a pattern macular dystrophy. She had no history of using medications with recognized toxic macular effects. Subsequent genetic testing confirmed a novel heterozygous missense variant of unknown significance in PRPH2 (PRPH2: c.694 G>A, p.(Ala232Thr)).

CONCLUSIONS

To our knowledge, this is the first case of macular dystrophy identified in a patient with SCA14. While it is possible that the macular dystrophy observed in this patient might be an under-reported phenotype associated with SCA14, the pattern of macular changes is consistent with PRPH2-related disorders. The identified missense variant is predicted to be damaging by most in silico models, and the residue is highly conserved, adding support to a dual genetic diagnosis in this case.

RPGR: Deep Phenotyping and Genetic Characterization With Findings Specific to the 3'-end of ORF15

Purpose

To describe a group of patients with retinitis pigmentosa GTPase regulator (RPGR)-related retinopathy with a tapetal-like retinal sheen and corresponding changes in the reflectivity of the ellipsoid zone on optical coherence tomography (OCT) imaging.

Methods

A retrospective case series of 66 patients with a disease-causing variant in RPGR was performed. An expert examiner, masked to patient demographics, clinical evaluations, and specific RPGR variant, analyzed color fundus photographs for the presence of a tapetal-like retinal sheen and assessed OCT images for the presence of an abnormally broad hyper-reflective band in the outer retina. Longitudinal reflectivity profiles were generated and compared with healthy controls.

Results

Twelve patients (18.2%) had a retinal sheen on color images that cosegregated with an abnormally broad hyper-reflective ellipsoid zone band on OCT imaging. Three-fourths of these patients were male, had a cone-rod dystrophy, and had pathogenic RPGR variants located toward the 3'-end of ORF15. This group had a different longitudinal reflectivity profile signature compared with controls. After a period of prolonged dark adaptation, the abnormal hyper-reflective band on OCT became less apparent, and the outer retinal layers adopted a more normal appearance.

Conclusions

RPGR-related retinopathy should be considered for males presenting with retinal sheen, abnormal ellipsoid zone hyper-reflectivity, and cone or cone-rod dysfunction on ERG, and pursued with molecular testing. Our results have implications for understanding the role of the C-terminal domain encoded by RPGR ORF15 in the phototransduction cascade. Further, the findings may be important to incorporate into both inclusion criteria and outcome measure developments in future RPGR-related cone or cone-rod dystrophy clinical trials.

A 10-year analysis of traumatic open-globe injuries in Edmonton, Canada, from 2009-2018

PURPOSE

To identify and characterize the incidence and correlates of open-globe injuries documented at the Eye Institute of Alberta (EIA) at the Royal Alexandra Hospital in Edmonton.

STUDY DESIGN

A 10-year single-centre retrospective chart review.

METHODS

All patients who underwent traumatic open-globe injury repair at EIA from January 2009-December 2018 were identified using key search terms. Charts were individually assessed for key demographic variables, including mechanism and location of injury. Patterns in open-globe injury incidence over the 10-year period and across demographics were assessed using Poisson regression. Associations between key demographic variables also were analyzed.

RESULTS

In total, 551 traumatic open-globe injuries were treated at the EIA from January 2009-December 2018, resulting in an average of 4.63 injuries per month over the 10-year period. Mean patient age was 42 ± 21.56 years. The number of males (n = 442) presenting for open-globe injury repair was 3.9 times higher than that for females (n = 114). Among patients for whom use of eye protection was recorded (n = 186), only 11% reported using eye protection at the time of the trauma. The incidence rate of injuries with zone 3 involvement was significantly higher in males (41.4%) than in females (29.8%).

CONCLUSION

Open-globe injuries remain a significant source of ocular morbidity at EIA, averaging just over 1 emergency case a week. Given the strong association with sex and the infrequent use of eye protection, targeted public health strategies are necessary to mitigate the risk of these sight-threatening injuries.

Central retinal artery occlusion: a retrospective study of disease presentation, treatment, and outcomes

OBJECTIVE

A central retinal artery occlusion (CRAO) represents a form of ocular stroke with poor visual prognosis. CRAO shares a common pathophysiology with cerebral ischemic stroke but presents unique diagnostic and management challenges leading to variability in clinical practice. This study aims to assess the presentation, treatment, and outcomes of CRAO at a tertiary care centre in Canada over 2 years and elucidate potential areas for improvement in the care of these patients.

METHODS

Single-institution retrospective review including 27 patients diagnosed with CRAO from March 2018 to March 2020 in Edmonton, Alberta.

RESULTS

Most patients with CRAO presented to eye care providers (14 of 27); others presented to the emergency department (10 of 27) or family physicians (2 of 27). Three patients (11.1%) presented within 4.5 hours of symptom onset. At presentation, 81% of patients had visual acuity of 20/400 or worse in the affected eye. No patients received thrombolysis. The majority of CRAO cases had a nonarteritic etiology (92.6%). All patients had at least one pre-existing vascular risk factor. Forty-eight percent of patients received escalated medical therapy. Ipsilateral carotid stenosis was identified in 5 patients (18.5%); 3 patients required carotid endarterectomy. Two patients were diagnosed with atrial fibrillation. Two patients experienced symptomatic cerebral ischemia within 6 weeks of CRAO.

CONCLUSIONS

The majority of patients with CRAO presented to eye care providers, and few present within the potential window for thrombolysis of 4.5 hours, highlighting the need for public awareness strategies. Our cohort highlights the significant rate of systemic comorbidity that exists in these patients.

Long-term efficacy and safety of inotersen in patients with hereditary transthyretin amyloid polyneuropathy with or without cardiomyopathy: post hoc analysis of NEURO-TTR open-label extension

Background/Introduction

Cardiomyopathy (CM) with associated heart failure and polyneuropathy (PN) are common manifestations of hereditary transthyretin amyloidosis (ATTRv), a progressive, debilitating, and fatal disease that results from the deposition of misfolded transthyretin (TTR) protein throughout the body. NEURO-TTR (NCT01737398) showed that inotersen, an antisense oligonucleotide inhibitor of TTR protein production, slowed the progression of PN and maintained quality of life in patients with ATTRv.

Purpose

To report efficacy and safety from the open-label extension (OLE) of the NEURO-TTR study in patients with ATTRv PN overall and in CM subgroups.

Methods

Patients who completed NEURO-TTR, enrolled in the OLE (NCT02175004), and either switched from placebo in NEURO-TTR to inotersen in the OLE (placebo-inotersen) or received inotersen in NEURO-TTR and remained on inotersen in the OLE (inotersen-inotersen) were included. Assessments included the modified Neuropathy Impairment Score +7 composite score (mNIS+7 [range –22.3 to 346.3], a measure of neuropathy with higher scores indicative of poorer function), TTR levels, and safety monitoring. Utilizing patients from Europe and North America (EU+NA) as of 28 July 2020, this post hoc analysis examined two subgroups: CM ECHO and severe CM ECHO. CM was defined as a diagnosis of ATTRv CM at study entry or all of the following criteria: a left ventricular wall thickness of ≥1.3 cm on transthoracic echocardiography at baseline, no known history of persistent hypertension (systolic blood pressure ≥150 mm Hg) within 12 months before study screening, and evaluable baseline ECHO obtained by central assessment. Severe CM was defined as an interventricular septum thickness ≥1.5 cm at baseline. Descriptive statistics are reported.

Results

In the overall population and both CM subgroups, the placebo-inotersen group demonstrated slowing of neurological disease progression compared with natural history based on NEURO-TTR placebo projection (estimated natural history will be presented). Furthermore, in the overall population and both CM subgroups, the inotersen-inotersen group demonstrated sustained benefit compared with the placebo-inotersen group (Table). Change in serum TTR levels will be presented. There have been no reports of grade 4 thrombocytopenia or acute glomerulonephritis under enhanced monitoring in patients in the EU+NA despite the increased duration of exposure. No new safety concerns were identified.

Conclusions

Inotersen treatment for >3 years slowed the progression of PN associated with ATTRv in patients with CM, including severe CM. In both subgroups, greater neurological preservation was observed in those who initiated inotersen earlier (inotersen-inotersen group), underscoring the benefits of early treatment. No new safety signals were detected in this OLE analysis; enhanced monitoring is successful in managing the risk for thrombocytopenia and acute glomerulonephritis.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): This study was sponsored by Akcea Therapeutics, an affiliate of Ionis Pharmaceuticals, Inc.

Nonosseous Periocular Manifestations of Langerhans Cell Histiocytosis: A Case Report and Systematic Review

PURPOSE

Langerhans cell histiocytosis (LCH) is a disorder of dendritic cell proliferation that typically involves bone. It can be diagnostically challenging when LCH presents without bony involvement, leading to delays in diagnosis and treatment. In this study, the periocular manifestations of LCH in cases where the underlying orbital bones are not involved are described through a systematic review.

METHODS

A systematic review of the literature was performed to capture all cases of LCH that involved the periocular region but not the underlying orbital bones. These included LCH cases that involved the periocular skin, the ocular surface, and the orbital tissue. The authors also highlight an additional case where LCH presented with periocular edema and multifocal, nodular conjunctival lesions.

RESULT

This review illustrates that LCH rarely presents with periocular infiltration without orbital bone involvement. In these atypical cases, LCH can present as an eyelid mass, a chalazion-like lesion, generalized periocular swelling, ocular surface lesions, or infiltration of any orbital structure. Ocular surface LCH has a higher rate of recurrence than other periocular LCH. Orbital LCH can involve any tissue including extraocular muscles, the lacrimal gland, or indistinct areas within the orbit.

CONCLUSIONS

LCH is a clinicopathologic diagnosis. Although most cases involve the bone, any soft tissue can be involved. Biopsy is required to confirm the diagnosis of this heterogeneous disease.

PEX6 Mutations in Peroxisomal Biogenesis Disorders: An Usher Syndrome Mimic

PURPOSE

Peroxisomal biogenesis disorders (PBDs) represent a spectrum of conditions that result in vision loss, sensorineural hearing loss, neurologic dysfunction, and other abnormalities resulting from aberrant peroxisomal function caused by mutations in PEX genes. With no treatments currently available, we sought to investigate the disease mechanism in a patient with a PBD caused by defects in PEX6 and to probe whether overexpression of PEX6 could restore peroxisome function and potentially offer therapeutic benefit.

DESIGN

Laboratory-based study.

PARTICIPANTS

A 12-year-old boy sought treatment with hearing loss and retinopathy. After negative results in an Usher syndrome panel, targeted genetic testing revealed compound heterozygous mutations in PEX6. These included a 14-nucleotide deletion (c.802_815del: p.(Asp268Cysfs∗8)) and a milder missense variant (c.35T→C:(p.Phe12Ser)).

METHODS

Patient-derived skin fibroblasts were cultured, and a PEX6 knockout cell line was developed using clustered regularly interspaced short palindromic repeats and Cas9 technology in HEK293T cells to emulate a more severe disease phenotype. Immunoblot analysis of whole cell lysates was performed to assess peroxisome number. Immunofluorescence studies used antibodies against components of the peroxisomal protein import pathway to interrogate the effects of mutations in PEX6 on protein trafficking.

MAIN OUTCOME MEASURES

Primary outcome measures were peroxisome abundance and matrix protein import.

RESULTS

Peroxisome number was not significantly different between control fibroblasts and patient fibroblasts; however, fewer peroxisomes were observed in PEX6 knockout cells compared with wild-type cells (P = 0.04). Analysis by immunofluorescent microscopy showed significantly impaired peroxisomal targeting signal 1- and peroxisomal targeting signal 2-mediated matrix protein import in both patient fibroblasts and PEX6 knockout cells. Overexpressing PEX6 resulted in improved matrix protein import in PEX6 knockout cells.

CONCLUSIONS

Mutations in PEX6 were responsible for combined hearing loss and retinopathy in our patient. The primary peroxisomal defect in our patient's skin fibroblasts was impaired peroxisomal protein import as opposed to reduction in the number of peroxisomes. Genetic strategies that introduce wild-type PEX6 into cells deficient in PEX6 protein show promise in restoring peroxisome function. Future studies of patient-specific induced pluripotent stem cell-derived retinal pigment epithelium cells may clarify the role of PEX6 in the retina and the potential for gene therapy in these patients.

PHACOVITRECTOMY FOR PRIMARY RHEGMATOGENOUS RETINAL DETACHMENT REPAIR: A Retrospective Review

PURPOSE

To analyze the single surgery success rate and anterior segment complications related to phacoemulsification and intraocular lens implantation in a series of patients undergoing phacovitrectomy for all types of primary rhegmatogenous retinal detachment.

METHODS

We performed a retrospective interventional case series on 302 eyes undergoing phacovitrectomy for primary rhegmatogenous retinal detachment repair between November 1, 2016, and February 2, 2019, in Edmonton, Canada. Primary outcomes included single surgery retinal reattachment rate and anterior segment complications. Secondary outcomes included the effects of proliferative vitreoretinopathy and macula and/or peripheral internal limiting membrane peeling on the rate of surgical success.

RESULTS

The single surgery success rate of phacovitrectomy for all types of primary rhegmatogenous retinal detachment was 85.1%. The presence of proliferative vitreoretinopathy was associated with lower surgical success (odds ratio, 0.33; P = 0.01). Macular internal limiting membrane peeling was associated with higher surgical success (odds ratio, 2.4; P = 0.05). Anterior segment complications included posterior capsular opacification (28.8%), posterior synechiae (10.9%), and posterior capsular rupture (2.3%).

CONCLUSION

Phacovitrectomy is a safe and effective treatment option for the primary repair of rhegmatogenous retinal detachments. This study provides evidence to support the safe incorporation of phacoemulsification and intraocular lens implantation with retinal surgery.

Severe retinal degeneration in a patient with Canavan disease

Background: Canavan disease is an autosomal recessive, neurodegenerative disorder caused by mutations in ASPA, a gene encoding the enzyme aspartoacylase. Patients present with macrocephaly, developmental delay, hypotonia, vision impairment and accumulation of N-acetylaspartic acid. Progressive white matter changes occur in the central nervous system. The disorder is often fatal in early childhood, but milder forms exist. Materials and methods: Case report. Results: We present the case of a 31-year-old male with mild/juvenile Canavan disease who had severe vision loss due to a retinal degeneration resembling retinitis pigmentosa. Prior to this case, vision loss in Canavan disease had been attributed to optic atrophy based on fundoscopic evidence of optic nerve pallor. Investigations for an alternative cause for our patient's retinal degeneration were non-revealing. Conclusion: We wonder if retinal degeneration may not have been previously recognized as a feature of Canavan disease. We highlight findings from animal models of Canavan disease to further support the association between Canavan disease and retinal degeneration.

A diagnostic approach to syndromic retinal dystrophies with intellectual disability

Inherited retinal dystrophies are a group of monogenic disorders that, as a whole, contribute significantly to the burden of ocular disease in both pediatric and adult patients. In their syndromic forms, retinal dystrophies can be observed in association with intellectual disability, frequently alongside other systemic manifestations. There are now over 80 genes implicated in syndromic retinal dystrophies with intellectual disability. Identifying and accurately characterizing these disorders allows the clinician to narrow the differential diagnosis, evaluate for relevant associated features, arrive at a timely and accurate diagnosis, and address both sight-threatening ocular manifestations and morbidity-causing systemic manifestations. The co-occurrence of retinal dystrophy and intellectual disability in an individual can be challenging to investigate, diagnose, and counsel given the considerable phenotypic and genotypic heterogeneity that exists within this broad group of disorders. We performed a review of the current literature and propose an algorithm to facilitate the evaluation, and clinical and mechanistic classification, of these individuals.

Improved electroretinographic responses following dietary intervention in a patient with Refsum disease

Refsum disease is a rare inherited metabolic disorder arising from a defect in peroxisomal metabolism. Patients lack the functional enzyme phytanoyl-CoA hydroxylase, resulting in perturbed alpha oxidation of fatty acids. Phytanic acid accumulates in nervous and adipose tissue and leads to several disease phenotypes including early-onset retinal degeneration, hearing loss, peripheral neuropathy, anosmia, and cerebellar ataxia, among others. Currently, restricting dietary phytanic acid is the only means of altering the chronic sequelae and the disease course. While dietary intervention has been demonstrated to improve peripheral neuropathy, ichthyosis, and ataxia, there have been no reports of improved retinal function in patients with Refsum disease. We describe the case of a 51-year-old patient with molecularly and biochemically confirmed Refsum disease who underwent electroretinography before and after beginning a phytanic acid-restricted diet. His post-intervention 30 Hz flicker electroretinogram demonstrated significantly improved waveform amplitudes and implicit times, suggesting improved retinal function. Thus, we propose that the possibility exists for some visual recovery in these patients and we highlight the utility of performing standardized electroretinography to assess treatment response in Refsum disease.

Diagnosis and Screening of Patients with Hereditary Transthyretin Amyloidosis (hATTR): Current Strategies and Guidelines

The outlook for transthyretin amyloidosis (ATTR) is changing with the availability of new and emerging treatments. ATTR now appears to be more common than previously thought and is no longer viewed as an obscure diagnosis with a grim prognosis. Now more than ever, there is growing emphasis on the need for early diagnosis because the treatments appear to be most effective if started in earlier stages of the disease. Diagnosing ATTR is a challenge as it may initially present with nonspecific symptoms and it is often thought of as a diagnosis of exclusion. Increased awareness is imperative as new treatments offer hope and have the potential to change the disease trajectory. ATTR commonly presents with neurological and cardiac features. Transthyretin (TTR) is a protein produced in the liver which misfolds either due to genetic mutations or due to aging and results in deposition of amyloid fibrils in organs and tissues. Apart from the traditional imaging modalities, newer techniques including echocardiographic strain imaging, magnetic resonance imaging (MRI), and nuclear scintigraphy, as well as the increased availability of genetic testing are aiding in making a timely diagnosis. In this review, we present the current understanding of the ATTR disease process, diagnostic and surveillance approaches, newer treatment modalities, and the future directions.

Diffuse Pigmented Lesions in the Outer Retina: An Unusual Fundus Appearance

Purpose:

This report describes and provides a differential diagnosis for a patient with unusual bilateral retinal pigmented lesions.

Methods:

A 40-year-old woman was found to have multiple flat, gray lesions scattered across her fundi, becoming larger and more confluent toward the periphery. There were small drusenlike deposits in her foveae. The hyperpigmented lesions demonstrated hypoautofluorescence with thickening of the retinal pigment epithelium and disruption of the overlying layers on optical coherence tomography (OCT). Full-field electroretinography revealed generalized reduced a- and b-wave amplitudes.

Results:

Chest x-ray, breast ultrasound, mammography, and pelvic ultrasound findings were negative for malignant etiologic factors. Panel testing results for hereditary retinal dystrophy were negative.

Conclusions:

Although the clinical and OCT appearance of the lesions is similar to congenital grouped pigmentation, the symmetric and bilateral nature of ocular findings coupled with electroretinographic changes suggest a possible retinal dystrophy. This case adds to the phenotypic diversity of pigmented fundus lesions.

Early data on long-term efficacy and safety of inotersen in patients with hereditary transthyretin amyloidosis: a 2-year update from the open-label extension of the NEURO-TTR trial

BACKGROUND AND PURPOSE

Hereditary transthyretin (hATTR) amyloidosis causes progressive polyneuropathy resulting from transthyretin (TTR) amyloid deposition throughout the body, including the peripheral nerves. The efficacy and safety of inotersen, an antisense oligonucleotide inhibitor of TTR protein production, were demonstrated in the pivotal NEURO-TTR study in patients with hATTR polyneuropathy. Here, the long-term efficacy and safety of inotersen are assessed in an ongoing open-label extension (OLE) study.

METHODS

Patients who completed NEURO-TTR were eligible to enroll in the OLE (NCT02175004). Efficacy assessments included the modified Neuropathy Impairment Score plus seven neurophysiological tests composite score (mNIS + 7), the Norfolk Quality of Life - Diabetic Neuropathy (Norfolk QOL-DN) questionnaire total score and the Short-Form 36 Health Survey (SF-36) Physical Component Summary (PCS) score. Safety and tolerability were also assessed.

RESULTS

Overall, 97% (135/139) of patients who completed NEURO-TTR enrolled in the OLE. Patients who received inotersen for 39 cumulative months in NEURO-TTR and the OLE continued to show benefit; patients who switched from placebo to inotersen in the OLE demonstrated improvement or stabilization of neurological disease progression by mNIS + 7, Norfolk QOL-DN and SF-36 PCS. No new safety concerns were identified. There was no evidence of increased risk for grade 4 thrombocytopenia or severe renal events with increased duration of inotersen exposure.

CONCLUSION

Inotersen slowed disease progression and reduced deterioration of quality of life in patients with hATTR polyneuropathy. Early treatment with inotersen resulted in greater long-term disease stabilization than delayed initiation. Routine platelet and renal safety monitoring were effective; no new safety signals were observed.

An analysis of strabismus reoperations in Northern Alberta, Canada from 1995 to 2015

OBJECTIVE

To report the reoperation rate in a large group of pediatric and adult strabismus patients over a 21-year period in Northern Alberta, Canada.

METHODS

A retrospective review of 6177 strabismus surgeries from July 1995 to June 2015 on 5125 pediatric and adult patients was conducted to determine the reoperation rate at a single major referral centre. A set of guidelines was implemented in November 2014 recommending delaying reintervention for at least 12 weeks from the initial surgery, with specific exceptions.

RESULTS

The historical strabismus reoperation rate over a 21-year period was 15.7%. Of those surgeries requiring reoperation, 77.7% required only 1 reoperation, 17.1% required 2 reoperations, 3.1% required 3 reoperations, and 2.1% required 4 or more reoperations. The mean time between surgeries for patients undergoing reoperation was 2.3 years and the median time was 1.0 years.

CONCLUSIONS

Our study provides insight into the strabismus reoperation rate and the number of subsequent surgeries performed for patients over a 21-year period. Although preoperative ocular alignment, comorbidities, and the status of the operative eye modify the probability of reoperation, our results from a large cohort of patients provide an impression of the rate of reoperation and may be of benefit in the preoperative counseling of patients. Furthermore, we highlight the scarcity of guidelines for the appropriate timing of reoperation. The implementation of specific guidelines may encourage future investigation into trends in reoperation over time and promote ways to avoid unnecessary surgeries, lower health care costs to stakeholders, and ultimately improve patient care.

A diagnosis of Stevens-Johnson Syndrome (SJS) in a patient presenting with superficial keratitis

Purpose

To describe a case of Stevens-Johnson syndrome (SJS) diagnosed in a patient presenting with primarily ocular findings where SJS had not been initially suspected.

Observations

A 23-year-old female presented with a 2 day history of bilateral eye pain, conjunctival injection, decreased visual acuity, and photophobia in the context of a 4 day history of fever, headache, and sore throat. She was found to have bilateral superficial keratitis and treated for suspected early infectious keratitis secondary to extended contact lens wear. She returned the next day with worsening visual symptoms, a new macular rash over her upper torso, and new ulcerating lesions over her buccal and perioral tissue. The patient was diagnosed with SJS. She was successfully treated using systemic cyclosporine with antibiotics and steroid eye drops.

Conclusions and importance

Ophthalmologists may be the first physicians to diagnose SJS, a life-threatening condition that can initially present with non-specific viral prodromal symptoms and ocular signs alone. This case emphasizes the importance of considering a patient's entire clinical history, especially when the presentation is atypical and the diagnosis is not obviously apparent.

Analysis of penetrating keratoplasty in Northern Alberta, Canada, from 2000 to 2015

OBJECTIVE

To study indications for penetrating keratoplasty (PK) at a single site. The trends in the causative organisms for infectious keratitis requiring surgery were also evaluated.

DESIGN

Retrospective observational study.

PARTICIPANTS

A total of 1181 eyes of 935 patients undergoing PK between January 2000 and December 2015 in Northern Alberta, Canada.

METHODS

Indications for PK were evaluated over the 16-year study period, and the trends in these indications were compared over 5-year intervals. The microbiology of infectious keratitis cases requiring surgery was similarly evaluated.

RESULTS

The most common indications for PK from 2000 to 2015 were keratoconus (23%), re-graft (22%), and corneal scar (12%). There was a decline in the percent of total surgeries done for Fuchs' dystrophy (p = 1.1 × 10^-3) and pseudophakic bullous keratopathy (p = 5.6 × 10^-5), whereas a corresponding increase in keratoconus (p = 3.2 × 10^-5), trauma (p = 2.1 × 10^-3), and infectious keratitis cases (p = 0.010) was observed. The most common causes for infectious keratitis cases were viral (45%), bacterial (18%), parasitic (11%), and fungal (9%). There was a significant increase in the percent of infectious keratitis cases due to a viral etiology from 2005 to 2010 (p = 6.4 × 10^-3).

CONCLUSIONS

The indications for PK are comparable with other centres in North America. Nearly half of all infectious keratitis cases requiring surgery are viral. The increase in viral cases requiring surgery may reflect improved diagnostics or recurrent cases.

A targeted approach to genome-wide studies reveals new genetic associations with central corneal thickness

PURPOSE

To evaluate the ability of a targeted genome-wide association study (GWAS) to identify genes associated with central corneal thickness (CCT).

METHODS

A targeted GWAS was used to investigate whether ten candidate genes with known roles in corneal development were associated with CCT in two Singaporean populations. The single nucleotide polymorphisms (SNPs) within a 500 kb interval encompassing each candidate were analyzed, and in light of the resulting data, members of the Wnt pathway were subsequently screened using similar methodology.

RESULTS

Variants within the 500 kb interval encompassing three candidate genes, DKK1 (rs1896368, p=1.32×10^-3), DKK2 (rs17510449, p=7.34×10^-4), and FOXO1 (rs7326616, p=1.56×10^-4 and rs4943785, p=1.19×10^-3), were statistically significantly associated with CCT in the Singapore Indian population. DKK2 was statistically significantly associated with CCT in a separate Singapore Malaysian population (rs10015200, p=2.26×10^-3). Analysis of Wnt signaling pathway genes in each population demonstrated that TCF7L2 (rs3814573, p=1.18×10^-3), RYK (rs6763231, p=1.12×10^-3 and rs4854785, p=1.11×10^-3), and FZD8 (rs640827, p=5.17×10^-4) were statistically significantly associated with CCT.

CONCLUSIONS

The targeted GWAS identified four genes (DKK1, DKK2, RYK, and FZD8) with novel associations with CCT and confirmed known associations with two genes, FOXO1 and TCF7L2. All six participate in the Wnt pathway, supporting a broader role for Wnt signaling in regulating the thickness of the cornea. In parallel, this study demonstrated that a hypothesis-driven candidate gene approach can identify associations in existing GWAS data sets.

Maternal collapse: Challenging the four-minute rule

Introduction

The current approach to, cardiopulmonary resuscitation of pregnant women in the third trimester has been to adhere to the “four-minute rule”: If pulses have not returned within 4 min of the start of resuscitation, perform a cesarean birth so that birth occurs in the next minute. This investigation sought to re-examine the evidence for the four-minute rule.

Methods

A literature review focused on perimortem cesarean birth was performed using the same key words that were used in formulating the “four-minute rule.” Maternal and neonatal injury free survival rates as a function of arrest to birth intervals were determined, as well as actual incision to birth intervals.

Results

Both maternal and neonatal injury free survival rates diminished steadily as the time interval from maternal arrest to birth increased. There was no evidence for any specific survival threshold at 4 min. Skin incision to birth intervals of 1 min occurred in only 10% of women.

Conclusion

Once a decision to deliver is made, care providers should proceed directly to Cesarean birth during maternal cardiac arrest in the third trimester rather than waiting for 4 min for restoration of the maternal pulse. Birth within 1 min from the start of the incision is uncommon in these circumstances.

•

Half of maternal/fetal pairs who are delivered by Cesarean birth within 25 min survive without injury.

•

The injury free survival rate for both has a roughly linear decrease as the time interval from arrest to birth increases.

•

Very few babies could be delivered within 1 min of the Cesarean section incision.

This information suggests that the current cardio-pulmonary resuscitation guideline in pregnancy, known as the four-minute rule, needs to be changed. Injury free survival for both mother and baby decreases steadily from the moment of cardiac arrest until cesarean birth. Furthermore, in actual practice, the baby usually cannot be delivered within 1 min of the start of surgery. Once a decision for delivery has been made, Cesarean birth should be initiated promptly without waiting for 4 min. In practice, the recommendation to proceed to cesarean birth without delay is also likely to result in less confusion than the current “Four-Minute rule.”

Bilateral uveitis and Usher syndrome: a case report

Introduction

Usher syndrome is a genetically heterogeneous condition and represents the most common cause of inherited combined vision and hearing loss. Deficits manifest as sensorineural hearing loss that typically develops at a young age and retinitis pigmentosa that can lead to peripheral vision loss and night blindness. As a result, this syndrome can have a significant impact on a patient’s quality of life.

Previous studies have described an association between Usher syndrome and Fuchs’ heterochromic iridocyclitis, a form of non-granulomatous uveitis that generally presents in a unilateral manner. We present a rare finding of bilateral uveitis and, to the best of our knowledge, the first report of granulomatous uveitis as a feature in a patient with Usher syndrome.

Case presentation

A 45-year-old Caucasian woman with a known history of retinitis pigmentosa presented to our clinic with suspected Usher syndrome, given her report of long-standing hearing loss. Aside from a mild loss in visual acuity, our patient was otherwise asymptomatic. Visual field testing, audiology and electroretinography findings supported the diagnosis of Usher syndrome. With slit lamp examination she was found to have bilateral keratic precipitates, with large, greasy-white, mutton-fat keratic precipitates on the endothelial surface of her left eye. A thorough work-up that included blood tests and imaging was negative for an alternative cause of her uveitis.

Conclusion

We present a rare finding of bilateral uveitis and what we believe to be the first reported instance of mutton-fat keratic precipitates and granulomatous uveitis as a feature in a patient with Usher syndrome. By identifying atypical presentations of the disease, we hope to contribute to the range of ophthalmic conditions that may be seen in association with Usher syndrome.

Amniotic fluid embolism: Then and now

BACKGROUND

The first case report to describe amniotic fluid embolism that appeared in 1926 in Basil-Medico is translated from Portuguese to English.

CASE

A patient with a dead fetus for several weeks, presented in labor and died suddenly with fetal squames evident in the maternal pulmonary vasculature at autopsy.

CONCLUSION

As can be seen from the translation, this case report is remarkably similar in many of its features to some of the eight patients described 15 years later in the first English language discussion of the disease by Steiner and Luschbaugh in JAMA. An enigma presented by this first case remains today: fetal material in the maternal pulmonary vasculature appears specific for amniotic fluid embolism at autopsy but not in living patients.

Palmitoylation is the switch that assigns calnexin to quality control or ER Ca2+ signaling

The palmitoylation of calnexin serves to enrich calnexin on the mitochondria-associated membrane (MAM). Given a lack of information on the significance of this finding, we have investigated how this endoplasmic reticulum (ER)-internal sorting signal affects the functions of calnexin. Our results demonstrate that palmitoylated calnexin interacts with sarcoendoplasmic reticulum (SR) Ca(2+) transport ATPase (SERCA) 2b and that this interaction determines ER Ca(2+) content and the regulation of ER-mitochondria Ca(2+) crosstalk. In contrast, non-palmitoylated calnexin interacts with the oxidoreductase ERp57 and performs its well-known function in quality control. Interestingly, our results also show that calnexin palmitoylation is an ER-stress-dependent mechanism. Following a short-term ER stress, calnexin quickly becomes less palmitoylated, which shifts its function from the regulation of Ca(2+) signaling towards chaperoning and quality control of known substrates. These changes also correlate with a preferential distribution of calnexin to the MAM under resting conditions, or the rough ER and ER quality control compartment (ERQC) following ER stress. Our results have therefore identified the switch that assigns calnexin either to Ca(2+) signaling or to protein chaperoning.

Pulmonary embolism in pregnancy. Consensus and controversies

Venous thrombotic events (VTE) occur 1-2 per 10,000 pregnancies and remain one of the leading causes of maternal mortality in the developed world. The two largest risk factors are a personal history of VTE and heritable thrombophilias. D-dimer tests for VTE in pregnancy have a high false positive rate and at least some false negatives have been reported. Compression ultrasound should be used to evaluate pregnant women for deep venous thrombosis followed by magnetic resonance imaging of the pelvis for a negative test and strong remaining clinical suspicion. For pulmonary embolism, a chest x-ray should be used to triage the patient to either a ventilation/perfusion study after a normal X-ray or a CT pulmonary angiogram after an abnormal one. Treatment generally consists of low molecular weight heparin through a minimum of six weeks post-partum. Thombolysis might have merit in life-threatening, massive pulmonary embolism. VTE prophylaxis in at-risk populations remains a major area of uncertainty. Mechanical prophylaxis for all women undergoing cesarean, in particular, has a paucity of supportive evidence.

Palmitoylated TMX and calnexin target to the mitochondria-associated membrane

The mitochondria-associated membrane (MAM) is a domain of the endoplasmic reticulum (ER) that mediates the exchange of ions, lipids and metabolites between the ER and mitochondria. ER chaperones and oxidoreductases are critical components of the MAM. However, the localization motifs and mechanisms for most MAM proteins have remained elusive. Using two highly related ER oxidoreductases as a model system, we now show that palmitoylation enriches ER-localized proteins on the MAM. We demonstrate that palmitoylation of cysteine residue(s) adjacent to the membrane-spanning domain promotes MAM enrichment of the transmembrane thioredoxin family protein TMX. In addition to TMX, our results also show that calnexin shuttles between the rough ER and the MAM depending on its palmitoylation status. Mutation of the TMX and calnexin palmitoylation sites and chemical interference with palmitoylation disrupt their MAM enrichment. Since ER-localized heme oxygenase-1, but not cytosolic GRP75 require palmitoylation to reside on the MAM, our findings identify palmitoylation as key for MAM enrichment of ER membrane proteins.

Ero1alpha requires oxidizing and normoxic conditions to localize to the mitochondria-associated membrane (MAM)

Protein secretion from the endoplasmic reticulum (ER) requires the enzymatic activity of chaperones and oxidoreductases that fold polypeptides and form disulfide bonds within newly synthesized proteins. The best-characterized ER redox relay depends on the transfer of oxidizing equivalents from molecular oxygen through ER oxidoreductin 1 (Ero1) and protein disulfide isomerase to nascent polypeptides. The formation of disulfide bonds is, however, not the sole function of ER oxidoreductases, which are also important regulators of ER calcium homeostasis. Given the role of human Ero1alpha in the regulation of the calcium release by inositol 1,4,5-trisphosphate receptors during the onset of apoptosis, we hypothesized that Ero1alpha may have a redox-sensitive localization to specific domains of the ER. Our results show that within the ER, Ero1alpha is almost exclusively found on the mitochondria-associated membrane (MAM). The localization of Ero1alpha on the MAM is dependent on oxidizing conditions within the ER. Chemical reduction of the ER environment, but not ER stress in general leads to release of Ero1alpha from the MAM. In addition, the correct localization of Ero1alpha to the MAM also requires normoxic conditions, but not ongoing oxidative phosphorylation.

Rab32 modulates apoptosis onset and mitochondria-associated membrane (MAM) properties

The mitochondria-associated membrane (MAM) has emerged as an endoplasmic reticulum (ER) signaling hub that accommodates ER chaperones, including the lectin calnexin. At the MAM, these chaperones control ER homeostasis but also play a role in the onset of ER stress-mediated apoptosis, likely through the modulation of ER calcium signaling. These opposing roles of MAM-localized chaperones suggest the existence of mechanisms that regulate the composition and the properties of ER membrane domains. Our results now show that the GTPase Rab32 localizes to the ER and mitochondria, and we identify this protein as a regulator of MAM properties. Consistent with such a role, Rab32 modulates ER calcium handling and disrupts the specific enrichment of calnexin on the MAM, while not affecting the ER distribution of protein-disulfide isomerase and mitofusin-2. Furthermore, Rab32 determines the targeting of PKA to mitochondrial and ER membranes and through its overexpression or inactivation increases the phosphorylation of Bad and of Drp1. Through a combination of its functions as a PKA-anchoring protein and a regulator of MAM properties, the activity and expression level of Rab32 determine the speed of apoptosis onset.

Metabolism of amyloid proteins

Metabolic processing of amyloid precursor proteins is an important factor in the genesis of practically all forms of amyloidosis. Of the three major forms of systemic amyloidosis, reactive amyloid (amyloid A protein; AA) formation shows the most consistent role of partial proteolysis of serum amyloid A (SAA) to AA proteins which form fibrils. Immunoglobulin amyloidosis is also usually associated with C-terminal degradation of the fibril precursor light chain protein. Although it is commonly thought that transthyretin amyloidosis is associated with fibril formation from the tetrameric circulating plasma transthyretin, chemical analyses of transthyretin fibril deposits show significant fragmentation of the fibril protein constituents. In addition, it has been documented that proteolytic fragments are the fibril subunit proteins in gelsolin, cystatin C. Alzheimer's beta-amyloid precursor protein and apolipoprotein AI (apoAI) amyloidoses. Notable exceptions to the role of proteolysis in amyloid fibril formation would appear to be the lysozyme and beta 2-microglobulin amyloidoses. Few studies have examined the metabolism of amyloid-forming proteins. Perhaps the best data are on apoAI, which show decreased plasma residence time for the amyloidogenic Gly26Arg apoAI (1.8 d vs. normal 4.5 d). Similarly, preliminary data show increased clearance of Val30Met transthyretin when compared with the wild-type protein (18 h vs. 26 h). Also, biosynthetically 35S-labelled SAA proteins reconstituted with HDL show increased plasma clearance of murine SAA2, the amyloid fibril subunit protein, when compared with murine SAA1. Few data are available on metabolism of amyloid immunoglobulin light chain proteins, but it has been shown that radiolabelled Bence-Jones proteins are cleared very rapidly from the circulation. A better understanding of the metabolism of precursor proteins in each of the amyloid deposition diseases will give insight into the mechanisms of fibril formation and pathogenesis of amyloidosis.

Cardiopulmonary distress during obstetrical anaesthesia: attempts to diagnose amniotic fluid embolism in a case series of suspected allergic anaphylaxis

BACKGROUND

Cardiopulmonary distress during obstetrical anaesthesia may result from a drug-induced allergic reaction, but, in the obstetrical setting, allergic anaphylaxis may be inseparable from amniotic fluid embolism in terms of the clinical presentation. Further investigations, using allergy tests and other laboratory analyses, are then needed to pursue a diagnostic clarification.

METHODS

Twelve women suspected of having developed anaphylaxis during obstetrical anaesthesia underwent allergy follow-up investigations and further serological tests with the amniotic fluid embolism marker sialyl Tn and complement factors (C3 and C4) in an attempt to differentiate amniotic fluid embolism from drug-induced allergic anaphylaxis.

RESULTS

The diagnostic programme revealed one case of probable amniotic fluid embolism and four cases of probable drug-induced allergic anaphylaxis. Of the remaining seven cases, there were two cases that, by diagnostic exclusion, could be classified as possible cases of amniotic fluid embolism. The cause of the reactions remained unresolved in five cases.

CONCLUSIONS

It can be difficult to differentiate between anaphylaxis and amniotic fluid embolism, especially amongst survivors. Diagnostic markers that can be applied on peripheral blood samples are promising, but larger studies are needed to validate their use in the diagnosis of causes of cardiopulmonary distress during obstetrical anaesthesia.

Diaphragmatic paralysis: the use of M mode ultrasound for diagnosis in adults

STUDY DESIGN

Retrospective, case series.

OBJECTIVES

To evaluate the use of M mode ultrasonography in the evaluation of diaphragmatic paralysis in adults.

SETTING

Radiology department, Princess Alexandra Hospital, Brisbane, Australia.

METHODS

Ten patients who were referred for evaluation of suspected diaphragmatic paralysis were evaluated using M mode ultrasound.

RESULTS

Three of the patients who were scanned demonstrated normal diaphragmatic movement. The M mode trace demonstrated normal movement of the diaphragm bilaterally with quiet respiration and a sharp upstroke on the sniff test (indicating normal caudal movement of the diaphragm). Six patients were found to have a unilateral diaphragmatic paralysis. Four of these patients were noted to have a raised hemi-diaphragm on chest radiography. Of the two who did not have a raised hemi-diaphragm on chest radiography, one was permanently ventilated. The M mode trace of the paralyzed side showed no active caudal movement of the diaphragm with inspiration and abnormal paradoxical movement (ie cranial movement on inspiration) particularly with the sniff test.

CONCLUSION

M mode ultrasonography is a relatively simple and accurate test for diagnosing paralysis of the diaphragm, in the adult population. It can be performed, if necessary, at the bedside and can be easily repeated if paralysis is not thought to be permanent.

EQUIPMENT

Philips ATL Sono CT 5000 using a 2-5 MHz curved linear transducer.

Intracellular ferritin accumulation in neural and extraneural tissue characterizes a neurodegenerative disease associated with a mutation in the ferritin light polypeptide gene

Abnormal accumulation of ferritin was found to be associated with an autosomal dominant slowly progressing neurodegenerative disease clinically characterized by tremor, cerebellar ataxia, parkinsonism and pyramidal signs, behavioral disturbances, and cognitive decline. These symptoms may appear sequentially over a period of 4 decades. Pathologically, intranuclear and intracytoplasmic bodies were found in glia and subsets of neurons in the central nervous system as well as in extraneural tissue. Biochemical analyses of these bodies isolated from the striatum and cerebellar cortex revealed that ferritin light polypeptide (FTL) and ferritin heavy polypeptide (FTH1) were the main constituents. Molecular genetic studies revealed a 2-bp insertion mutation in exon 4 of the FTL gene. The resulting mutant polypeptide is predicted to have a carboxy terminus that is altered in amino-acid sequence and length. In tissue sections, the bodies were immunolabeled by anti-ferritin and anti-ubiquitin antibodies and were stained by Perls' method for ferric iron. Synthetic peptides homologous to the altered and wild-type carboxy termini were used to raise polyclonal antibodies. These novel antibodies as well as an antibody recognizing FTH1 immunolabeled the bodies. This study of this disorder has provided additional knowledge and insights in the growing area of ferritin-related neurodegeneration.