Unbiased Pathogen Detection and Host Gene Profiling for Conjunctivitis

Rapid Pathogen Detection in Infectious Uveitis Using Nanopore Metagenomic Next-Generation Sequencing: A Preliminary Study

PURPOSE

We establish an accurate and rapid diagnostic method for pathogen detection in infectious uveitis using nanopore metagenomic next-generation sequencing (NGS).

METHODS

In eight patients with suspected infectious uveitis, we prospectively compared the accuracy and time taken for pathogen identification between conventional diagnostic methods, such as cultures and PCR, and nanopore metagenomic NGS.

RESULTS

All causative pathogens were identified using nanopore sequencing, while only five of the eight patients were confirmed positive for a specific pathogen using conventional methods. The overall sample-to-answer turnaround time of nanopore sequencing was much shorter than that of conventional methods in the bacterial and fungal infection (mean, 17 h vs. 4d, respectively; P = .028). The pathogens could be detected even when the quantity or quality of DNA was not optimal.

CONCLUSION

Nanopore metagenomic NGS is a promising diagnostic tool that can rapidly and accurately identify the causative pathogen in infectious uveitis.

Pathogen Surveillance for Acute Infectious Conjunctivitis

Importance

Acute infectious conjunctivitis is a common ocular condition with major public health consequences.

Objective

To assess regional variations and microbial etiologies of acute infectious conjunctivitis to guide treatment.

Design, Setting, and Participants

In this cross-sectional study, patients with presumed acute infectious conjunctivitis were enrolled in the study at 5 sites (Honolulu, Hawaii; Los Angeles, San Francisco, and San Diego, California; and Petah-Tikva, Israel) from March 2021 to March 2023. Patients with allergic or toxic conjunctivitis were excluded.

Main Outcomes and Measures

Pathogens were identified by unbiased RNA deep sequencing.

Results

In all, 52 patients (mean [range] age, 48 [7-80] years; 31 females [60%]) were enrolled at 5 sites (6 patients from Honolulu, 9 from San Diego, 11 from Los Angeles, 13 from San Francisco, and 13 from Petah-Tikva). RNA deep sequencing detected human adenovirus species D in one-quarter of patients (13 of 52). A wide range of pathogens, including human coronavirus 229E, SARS-CoV-2, and herpes simplex virus type 1, was also identified, as well as several bacteria and fungi. Moreover, 62% (32 of 52) of patients presented with purulent discharge, while only 8% (4 of 52) of patients had confirmed bacterial pathogens.

Conclusion and Relevance

In this cross-sectional study, pathogens associated with acute infectious conjunctivitis varied between all 5 sites in the US and Israel. Purulent discharge was a common presenting sign in this study, with a low specificity for bacteria-associated conjunctivitis, suggesting that further diagnostic workup may be necessary to inform antibiotic stewardship. Additional research on cost-effectiveness of using RNA deep sequencing is needed to ascertain whether it is better to monitor patients clinically until resolution of disease.

Laboratory Investigations in Infectious Uveitis

Laboratory investigations can play a significant role in the diagnosis and decision-making of infectious uveitis. Though direct demonstration of the infective organism remains the gold standard of diagnosis, it is not always possible with ocular tissues. Recent advancements in molecular techniques have made it possible to overcome these limitations and to identify the genomic DNA of pathogens associated with infectious uveitis. Techniques such as next-generation sequencing can analyze all DNA-based lifeforms, regardless of whether they are bacteria, fungi, viruses, or parasites and have been used in the laboratory diagnosis of intraocular inflammation. On the other hand, serological tests, though they dominate the diagnostic landscape of various infectious etiologies in uveitis in routine clinical practice, have varied specificities and sensitivities in different infectious uveitis. In this review, we focus on various methods of laboratory diagnosis of infectious uveitis and discuss the recent advances in molecular diagnosis and their role in various infectious clinical entities.

Heterogenous pathogen profile associated with acute conjunctivitis in Nepal

BACKGROUND

Infectious conjunctivitis is common in Nepal.

MATERIALS AND METHODS

This prospective study recruited 60 patients with presumed acute infectious conjunctivitis from the B.P. Koirala Lions Center for Ophthalmic Studies in Kathmandu, Nepal. Swabs from the conjunctiva and anterior nares were processed for metagenomic RNA deep sequencing (RNA-seq).

RESULTS

Pathogens were identified in 55% of cases. RNA viruses were the most common pathogen class identified. Severe acute respiratory syndrome coronavirus 2 was the most common RNA virus identified.

CONCLUSIONS

Acute infectious conjunctivitis varies by location. Contrary to expectations, RNA viruses predominated. Repeat surveillance may be useful and RNA-seq allows for detection of the unexpected pathogen including RNA viruses.

Apollo Rising: Acute Conjunctivitis Outbreak in India, 2022

Purpose

To identify pathogens associated with the 2022 conjunctivitis outbreak in Tamil Nadu, India.

Methods

This prospective study was conducted in November of 2022. Patients with presumed acute infectious conjunctivitis presenting to the Aravind Eye Clinic in Madurai, India were eligible. Anterior nares and conjunctival samples from participants were obtained and processed for metagenomic RNA deep sequencing (RNA-seq).

Results

Samples from 29 patients were sequenced. A pathogen was identified in 28/29 (97%) patients. Coxsackievirus A24v, a highly infectious RNA virus, was the predominant pathogen and detected in 23/29 patients. Human adenovirus D (HAdV-D), a DNA virus commonly associated with conjunctivitis outbreaks, was detected in the remaining patients (5/29). Hemorrhagic conjunctiva was documented in both HAdV-D and coxsackievirus A24v affected patients but was not the predominant clinical presentation. Phylogenetic analysis of coxsackievirus A24v revealed a recent divergence from the 2015 outbreak.

Conclusions

Coxsackievirus A24v and HAdV-D were co-circulating during the 2022 conjunctivitis outbreak in Tamil Nadu, India. Clinical findings were similar between patients with HAD-V and coxsackievirus A24v associated conjunctivitis. As high-throughput technologies become more readily accessible and cost-effective, unbiased pathogen surveillance may prove useful for outbreak surveillance and control.

Metagenomic Deep Sequencing for Orbital Inflammatory Disease

PURPOSE

Orbital inflammatory disease (OID) is a heterogeneous group of immunologic disorders whose etiology is often non-specific despite routine investigation. In this proof-of-concept study, metagenomic deep sequencing (MDS) is applied to examine host gene expression in two subtypes of OID.

METHODS

Prospectively collected lacrimal gland tissue from patients with OID was processed for MDS. Differential gene expression analysis was performed to evaluate for host transcriptome signatures. Proof-of-concept comparison was made between histologically confirmed samples of idiopathic dacryoadenitis and IgG4-related disease (IgG4-RD).

RESULTS

Twelve genes were identified to be differentially expressed between idiopathic dacryoadenitis and IgG4-RD. Differences in innate humoral immunity gene expression were observed. Several additional genes of interests were also found to be upregulated in idiopathic dacryoadenitis.

CONCLUSIONS

A unique transcriptome signature was found when comparing idiopathic dacryoadenitis to IgG4-RD. This suggests that MDS can identify differentially expressed genes in OID. Such insight could potentially provide a better understanding of host gene expression and the inflammatory pathways involved in OID.

Case Series: Unbiased Deep Sequencing Analysis of Acute Infectious Conjunctivitis in an Ambulatory Eye Center in Berkeley, California

SIGNIFICANCE

Acute infectious conjunctivitis poses significant challenges to eye care providers. It can be highly transmissible, and because etiology is often presumed, correct treatment and management can be difficult. This study uses unbiased deep sequencing to identify causative pathogens of infectious conjunctivitis, potentially allowing for improved approaches to diagnosis and management.

PURPOSES

This study aimed to identify associated pathogens of acute infectious conjunctivitis in a single ambulatory eye care center.

CASE REPORTS

This study included patients who presented to the University of California Berkeley eye center with signs and symptoms suggestive of infectious conjunctivitis. From December 2021 to July 2021, samples were collected from seven subjects (ages ranging from 18 to 38). Deep sequencing identified associated pathogens in five of seven samples, including human adenovirus D, Haemophilus influenzae , Chlamydia trachomatis , and human coronavirus 229E.

CONCLUSIONS

Unbiased deep sequencing identified some unexpected pathogens in subjects with acute infectious conjunctivitis. Human adenovirus D was recovered from only one patient in this series. Although all samples were obtained during the COVID-19 pandemic, only one case of human coronavirus 229E and no SARS-CoV-2 were identified.

Viruses Associated with Acute Conjunctivitis in Vanuatu

The first manifestation of a viral infection may be conjunctivitis. There are limited data on the etiology of viral conjunctivitis in Vanuatu, a country in the South Pacific Ocean. Patients presenting to one of two Vanuatu health centers with presumed infectious conjunctivitis were eligible if symptom onset was within 14 days of screening. Conjunctival and anterior nasal swabs were obtained and subjected to unbiased RNA deep sequencing (RNA-seq) to identify DNA and RNA viruses. For samples collected from May to November 2021, RNA-seq identified a viral etiology in 12/48 patients. Human adenovirus species were the most common viruses (58%) detected, followed by human herpes viruses (cytomegalovirus, varicella zoster virus, and human herpes 7 virus). Rhinovirus C, Epstein-Barr virus, and bocavirus were also detected. In summary, the etiology for viral conjunctivitis in Vanuatu appears broad. Unbiased testing may be useful for disease surveillance.

Deep Metagenomic Sequencing for Endophthalmitis Pathogen Detection Using a Nanopore Platform

PURPOSE

To evaluate the utility of nanopore sequencing for identifying potential causative pathogens in endophthalmitis, comparing culture results against full-length 16S rRNA nanopore sequencing (16S Nanopore), whole genome nanopore sequencing (Nanopore WGS), and Illumina (Illumina WGS).

DESIGN

Cross-sectional diagnostic comparison.

METHODS

Patients with clinically suspected endophthalmitis underwent intraocular vitreous biopsy as per standard care. Clinical samples were cultured by conventional methods, together with full-length 16S rRNA and WGS using nanopore and Illumina sequencing platforms.

RESULTS

Of 23 patients (median age 68.5 years [range 47-88]; 14 males [61%]), 18 cases were culture-positive. Nanopore sequencing identified the same cultured organism in all of the culture-positive cases and identified potential pathogens in two culture-negative cases (40%). Nanopore WGS was able to additionally detect the presence of bacteriophages in three samples. The agreements at genus level between culture and 16S Nanopore, Nanopore WGS, and Illumina WGS were 75%, 100%, and 78%, respectively.

CONCLUSIONS

Whole genome sequencing has higher sensitivity and provides a viable alternative to culture and 16S sequencing for detecting potential pathogens in endophthalmitis. Moreover, WGS has the ability to detect other potential pathogens in culture-negative cases. Whilst Nanopore and Illumina WGS provide comparable data, nanopore sequencing provides potential for cost-effective point-of-care diagnostics.

Peripheral Blood Transcriptome in Patients with Sarcoidosis-Associated Uveitis

PURPOSE

To identify peripheral blood transcriptome differences in uveitis patients with sarcoidosis compared to those with Vogt-Koyanagi-Harada (VKH) syndrome and controls.

METHODS

Ten patients with uveitis compatible with sarcoidosis (eight with pulmonary sarcoidosis, one with central nervous system sarcoidosis, and one with conjunctival sarcoidosis), nine patients with VKH, and nine healthy controls were prospectively enrolled.

RESULTS

Ten genes exhibited a four-fold difference in expression in sarcoidosis patients compared to controls, many being involved in regulating inflammatory processes or cellular responses to microbes.

CONCLUSIONS

This research suggests that the transcriptome in sarcoidosis is robust enough to be detected in the peripheral blood and that sarcoidosis can be distinguished from healthy controls. Differentially expressed genes may serve as candidates warranting further investigation with respect to disease pathophysiology and may provide additional information, such as ability to stratify patients based on associated disease severity and anatomical location of inflammation within the eye.

Application Progress of High-Throughput Sequencing in Ocular Diseases

Ocular diseases affect multiple eye parts and can be caused by pathogenic infections, complications of systemic diseases, genetics, environment, and old age. Understanding the etiology and pathogenesis of eye diseases and improving their diagnosis and treatment are critical for preventing any adverse consequences of these diseases. Recently, the advancement of high-throughput sequencing (HTS) technology has paved wide prospects for identifying the pathogenesis, signaling pathways, and biomarkers involved in eye diseases. Due to the advantages of HTS in nucleic acid sequence recognition, HTS has not only identified several normal ocular surface microorganisms but has also discovered many pathogenic bacteria, fungi, parasites, and viruses associated with eye diseases, including rare pathogens that were previously difficult to identify. At present, HTS can directly sequence RNA, which will promote research on the occurrence, development, and underlying mechanism of eye diseases. Although HTS has certain limitations, including low effectiveness, contamination, and high cost, it is still superior to traditional diagnostic methods for its efficient and comprehensive diagnosis of ocular diseases. This review summarizes the progress of the application of HTS in ocular diseases, intending to explore the pathogenesis of eye diseases and improve their diagnosis.

Acute Keratoconjunctivitis Resulting From Coinfection With Avian Newcastle Virus and Human Adenovirus

PURPOSE

The aim of this study was to report a case of human keratoconjunctivitis caused by both Newcastle disease virus (NDV) and human adenovirus.

METHODS

A 32-year-old-man presented with an acute unilateral keratoconjunctivitis that resolved with corneal scarring. On presentation, his conjunctival swab was collected for metagenomic sequencing.

RESULTS

The highest number of pathogen sequencing reads in the conjunctival sample mapped to the NDV. The second highest number of reads mapped to human adenovirus. Confirmation testing with directed reverse-transcription polymerase chain reaction also identified NDV in the specimen.

CONCLUSIONS

Newcastle conjunctivitis has not been reported for more than 40 years. Mixed infections, including zoonotic pathogens, may be more common than realized.

Comparison of 16S rDNA Amplicon Sequencing With the Culture Method for Diagnosing Causative Pathogens in Bacterial Corneal Infections

Purpose

The purpose of this study was to explore if 16S rDNA amplicon sequencing can improve the conventional diagnosis of causative pathogens for bacterial corneal infection.

Methods

Corneal scraping and conjunctiva and eyelid margin swab samples from infected eyes of patients diagnosed with "bacterial corneal infection" and conjunctiva and eyelid margin swab samples from a random eye of healthy participants were collected. Each swab was used for both aerobic and anaerobic cultures and 16S rDNA amplicon sequencing. The V3 to V4 region of the 16S rDNA was amplified using polymerase chain reaction (PCR) and sequenced on the Illumina HiSeq 2500 Sequencing Platform.

Results

The overall culture positivity rate for all 72 samples was 69% (72% in the bacterial keratitis group and 67% in the healthy control group), whereas 1719 operational taxonomic units in total were generated using 16S rDNA amplicon sequencing with each sample showing 123 to 337 different genera. Staphylococcus, Corynebacterium, Propionibacterium, and Micrococcus most frequently appeared in culture, whereas Streptococcus, Acinetobacter, and Lactobacillus were the most common genera, with large ratios in 16S rDNA amplicon sequencing. The causative pathogens detected by the two methods were inconsistent for most samples, except for several corneal samples.

Conclusions

We suggest that a combination of different techniques, such as clinical observation, microscopic analysis, culture, and next-generation sequencing techniques including 16S rDNA amplicon sequencing, should be used to comprehensively analyze pathogens in corneal and external ocular infections.

Translational Relevance

This paper uses a basic research methodology for studying the microbiome in ocular samples to help improve the diagnostic accuracy of corneal and external ocular infections.

The Role of Metagenomics and Next-Generation Sequencing in Infectious Disease Diagnosis

BACKGROUND

Metagenomic next-generation sequencing (mNGS) for pathogen detection is becoming increasingly available as a method to identify pathogens in cases of suspected infection. mNGS analyzes the nucleic acid content of patient samples with high-throughput sequencing technologies to detect and characterize microorganism DNA and/or RNA. This unbiased approach to organism detection enables diagnosis of a broad spectrum of infection types and can identify more potential pathogens than any single conventional test. This can lead to improved ability to diagnose patients, although there remains concern regarding contamination and detection of nonclinically significant organisms.

CONTENT

We describe the laboratory approach to mNGS testing and highlight multiple considerations that affect diagnostic performance. We also summarize recent literature investigating the diagnostic performance of mNGS assays for a variety of infection types and recommend further studies to evaluate the improvement in clinical outcomes and cost-effectiveness of mNGS testing.

SUMMARY

The majority of studies demonstrate that mNGS has sensitivity similar to specific PCR assays and will identify more potential pathogens than conventional methods. While many of these additional organism detections correlate with the expected pathogen spectrum based on patient presentations, there are relatively few formal studies demonstrating whether these are true-positive infections and benefits to clinical outcomes. Reduced specificity due to contamination and clinically nonsignificant organism detections remains a major concern, emphasizing the importance of careful interpretation of the organism pathogenicity and potential association with the clinical syndrome. Further research is needed to determine the possible improvement in clinical outcomes and cost-effectiveness of mNGS testing.

A case of fungal conjunctivitis with giant papillae treated surgically

Fungal conjunctivitis is a rare disorder, with low incidence and difficulty in diagnosis due to a lack of specific clinical findings. We report a case of fungal conjunctivitis which exhibited a specific clinical feature of giant papilla formation, and its diagnosis was a complex process. A 19-year-old woman with a history of atopic dermatitis and hard contact lens use was referred to us with a 3-month history of giant papillary conjunctivitis of the right eye in spite of treatment with antiallergic and corticosteroid eye drops, complicated by intraocular pressure elevation. The left eye showed no symptom of ocular surface disorder throughout the clinical course. The right eye did not respond to oral corticosteroid. Polymerase chain reaction of conjunctival scrapings against Chlamydia trachomatis was negative, and she was treated surgically by total papilla resection. Conjunctival giant papilla recurrence was not observed after surgery. Although the primary histopathological diagnosis was chronic inflammation due to atopic keratoconjunctivitis, repeated histopathological survey of excised conjunctival tissue including immunohistochemical staining revealed histiocytes, yeast type spores and hyphae, and phagocytosed spores and hyphae in macrophages. The causative organism was identified morphologically as a Candida species. Later, histopathological examination of a cervical swab revealed the presence of Candida sp. This rare case indicates that a fungal organism may underlie refractory conjunctivitis with specific giant papillary hypertrophy mimicking vernal keratoconjunctivitis.

Practical Guidance for Clinical Microbiology Laboratories: Diagnosis of Ocular Infections

The variety and complexity of ocular infections have increased significantly in the last decade since the publication of Cumitech 13B, Laboratory Diagnosis of Ocular Infections (L. D. Gray, P. H. Gilligan, and W. C. Fowler, Cumitech 13B, Laboratory Diagnosis of Ocular Infections, 2010). The purpose of this practical guidance document is to review, for individuals working in clinical microbiology laboratories, current tools used in the laboratory diagnosis of ocular infections. This document begins by describing the complex, delicate anatomy of the eye, which often leads to limitations in specimen quantity, requiring a close working bond between laboratorians and ophthalmologists to ensure high-quality diagnostic care. Descriptions are provided of common ocular infections in developed nations and neglected ocular infections seen in developing nations. Subsequently, preanalytic, analytic, and postanalytic aspects of laboratory diagnosis and antimicrobial susceptibility testing are explored in depth.

Evaluation of full-length nanopore 16S sequencing for detection of pathogens in microbial keratitis

BACKGROUND

Microbial keratitis is a leading cause of preventable blindness worldwide. Conventional sampling and culture techniques are time-consuming, with over 40% of cases being culture-negative. Nanopore sequencing technology is portable and capable of generating long sequencing reads in real-time. The aim of this study is to evaluate the potential of nanopore sequencing directly from clinical samples for the diagnosis of bacterial microbial keratitis.

METHODS

Using full-length 16S rRNA amplicon sequences from a defined mock microbial community, we evaluated and benchmarked our bioinformatics analysis pipeline for taxonomic assignment on three different 16S rRNA databases (NCBI 16S RefSeq, RDP and SILVA) with clustering at 97%, 99% and 100% similarities. Next, we optimised the sample collection using an ex vivo porcine model of microbial keratitis to compare DNA recovery rates of 12 different collection methods: 21-gauge needle, PTFE membrane (4 mm and 6 mm), Isohelix™ SK-2S, Sugi® Eyespear, Cotton, Rayon, Dryswab™, Hydraflock®, Albumin-coated, Purflock®, Purfoam and Polyester swabs. As a proof-of-concept study, we then used the sampling technique that provided the highest DNA recovery, along with the optimised bioinformatics pipeline, to prospectively collected samples from patients with suspected microbial keratitis. The resulting nanopore sequencing results were then compared to standard microbiology culture methods.

RESULTS

We found that applying alignment filtering to nanopore sequencing reads and aligning to the NCBI 16S RefSeq database at 100% similarity provided the most accurate bacterial taxa assignment. DNA concentration recovery rates differed significantly between the collection methods (p < 0.001), with the Sugi® Eyespear swab providing the highest mean rank of DNA concentration. Then, applying the optimised collection method and bioinformatics pipeline directly to samples from two patients with suspected microbial keratitis, sequencing results from Patient A were in agreement with culture results, whilst Patient B, with negative culture results and previous antibiotic use, showed agreement between nanopore and Illumina Miseq sequencing results.

CONCLUSION

We have optimised collection methods and demonstrated a novel workflow for identification of bacterial microbial keratitis using full-length 16S nanopore sequencing.

The Next Generation of Ocular Pathogen Detection

ABSTRACT

Metagenomic next-generation sequencing is a powerful method for pathogen detection that combines advanced genome sequencing technology with cutting-edge bioinformatics to analyze microbial populations. Metagenomic next-generation sequencing has the potential to identify uncommon, unculturable, and even previously unidentified pathogens from a clinical isolate. Of particular interest to ophthalmology, this robust data extraction can occur from very small volume clinical samples. Here we discuss the opportunities and limitations of this technique and their current and future application to ophthalmic diagnostics.

Research Trends and Hotspot Analysis of Conjunctival Bacteria Based on CiteSpace Software

OBJECTIVE

To sort out the literature related to conjunctival bacteria and summarize research hotspots and trends of this field.

MATERIALS AND METHODS

The relevant literature data from 1900 to 2019 was retrieved from the Web of Science Core Collection database. After manual selection, each document record includes title, author, keywords, abstract, year, organization, and citation. We imported the downloaded data into CiteSpace V (version 5.5R2) to draw the knowledge map and conduct cooperative network analysis, discipline and journal analysis, cluster analysis, and burst keyword analysis.

RESULTS

After manual screening, there were 285 relevant papers published in the last 28 years (from 1991 to 2019), and the number is increasing year by year. The publications of conjunctival bacteria were dedicated by 1381 authors of 451 institutions in 56 countries/regions. The United States dominates this field (82 literatures), followed by Germany (23 literatures) and Japan (23 literatures). Overall, most cited papers were published with a focus on molecular biology, genetics, nursing, and toxicology. Most papers fall into the category of ophthalmology, veterinary sciences, and pharmacology and pharmacy. The only organized cluster is the "postantibiotic effect," and the top 5 keywords with the strongest citation bursts include "postoperative endophthalmiti(s)," "infectious keratoconjunctiviti(s)," "conjunctiviti(s)," "resistance," and "diversity".

CONCLUSION

The global field of conjunctival bacteria has expanded in the last 28 years. The United States contributes most. However, there are little cooperation among authors and institutions. Overall, this bibliometric study organized one cluster, "postantibiotic effect", and identified the top 5 hotspots in conjunctival bacteria research: "postoperative endophthalmiti(s)," "infectious keratoconjunctiviti(s)," "conjunctiviti(s)," "resistance," and "diversity". Thus, further research focuses on these topics that may be more helpful to prevent ocular infection and improve prophylaxis strategies to bring a benefit to patients in the near future.

Metagenomic Deep Sequencing to Investigate for an Infectious Etiology of Iridocorneal Endothelial Syndrome

PURPOSE

Iridocorneal endothelial (ICE) syndrome is a group of rare ocular conditions that result from abnormal corneal endothelial cells, leading to secondary glaucoma, iris distortions, and corneal edema. The etiology of ICE is unknown, although it has been associated with viral infections, such as herpes simplex virus. In this study, we sought to identify an infectious etiology for ICE using advanced molecular techniques.

METHODS

Metagenomic RNA sequencing (MDS) is a high-throughput sequencing approach that can identify all pathogens in any clinical sample, including RNA viruses. Descemet membrane and aqueous fluid from patients with ICE syndrome were subjected to MDS testing.

RESULTS

Samples from 3 patients with ICE were analyzed. MDS was performed on the aqueous fluid of 3 patients and Descemet membrane and endothelial cell tissue from 1 patient. Viral pathogens were not identified in any of the samples.

CONCLUSIONS

We were unable to identify a viral etiology in the tissues of patients with the Chandler variant of ICE syndrome, although this study was limited by sample size.