Asymmetric preservation of choroidal pigmentation simulating choroidal nevus in two siblings with Waardenburg syndrome type 2A.

INTRODUCTION: In addition to sensorineural hearing loss, Waardenburg Syndrome (WS) may present with variable pigmentation of skin and choroid, which may simulate other life-threating conditions (e.g. melanoma). CASE REPORT: Two siblings ostensibly presented with unilateral choroidal pigmentary abnormalities concerning for choroidal tumour. Serial ophthalmic examination documented no lesion growth (base or height) whilst the apparent syndromic features (i.e. iris hypochromia, profound sensorineural hearing loss, SNHL), family history (autosomal dominant inheritance) and positive genetic testing (pathogenic MITF variant) led to a revised diagnosis of Waardenburg Syndrome type 2A. CONCLUSION: Sectoral preservation of choroidal pigmentation in WS is rarely associated with choroidal malignancy. Awareness of syndromic features (e.g. SNHL) and access to genetic testing may facilitate early accurate diagnosis (i.e. allay concern for malignancy), enable treatment of modifiable features (e.g. SNHL) and identify other affected relatives.

Molecular genetic diagnostics for inherited retinal dystrophies in the clinical setting.

OBJECTIVE: To evaluate the success of diagnostic genetic testing in inherited retinal dystrophy (IRD) patients in the clinical setting. DESIGN: Retrospective cohort analysis. PARTICIPANTS: A total of 446 consecutive participants from diverse ethnic backgrounds living in western Canada. METHODS: Clinical information was collected from participants, including family history, and they underwent a full ophthalmic examination with chart review. Those with a suspected IRD were offered panel-based genetic testing of 351 genes between March 1, 2019, and February 28, 2022. The main outcome measure was effect of the genetic testing results on clinical diagnosis. RESULTS: Genetic testing established a conclusive molecular diagnosis in 249 of 446 cases (55.8%), a clearly negative result in 90 of 446 cases (20.1%), and an inconclusive diagnosis in 108 of 446 cases (24.2%). Conclusive disease-causing variants were identified in 69 genes, and the most commonly affected genes were ABCA4 (31 variants), USH2A (25 variants), and RPGR (19 variants). The inconclusive group included likely novel autosomal dominant variants or a pathogenic variant with a variant of uncertain significance in the same gene for a recessive phenotype. Notably, an inconclusive molecular genetic diagnosis was seen in as many as 47.3% of East Asian participants with an outer retinal dystrophy. CONCLUSIONS: This study represents the largest review of molecular genetic testing in IRDs in Canada. That negative or inconclusive results obtained in approximately 45% of cases demonstrates that there is an important need for new research into molecular genetic causes of IRDs. This is particularly true in addressing the problem of interpreting a variant of uncertain significance in ethnic minorities.

Focus on people, the rest will follow.

BACKGROUND: The Staff College: Leadership in Healthcare (Staff College) annual lectures were launched in 2013, with Sir Robert Francis QC delivering the first lecture following his recent report into Mid Staffs.In 2015, the lecture was dedicated to the Staff College founder and visionary leader, Professor Aidan Halligan. In 2021, Dr Navina Evans CBE, at that time Chief Executive, Health Education England, and now also Chief Workforce Officer, NHS England, was invited to give The Staff College: Leadership in Healthcare annual keynote lecture. METHOD: The annual lecture is delivered free to an audience of Staff College alumni, friends and supporters, commissioners and their colleagues and associates within the health care sector. The lecture presentation has adapted to the changing times and audience, with 2020 being via a virtual environment online. 2021 saw our first hybrid, in person and streaming live lecture. RESULTS: On 29 November 2021, Dr Navina Evans CBE, gave the inspiring keynote lecture, 'Focus on the People and the rest will follow'. CONCLUSION: Navina shared powerful messages, searching and uncomfortable questions for leaders and touching personal stories. Navina spoke about the many narratives of equality and deep value of diversity for society, the importance of leaders understanding the impact of their behaviours and the role of feedback, the need to understand what we're doing to prevent change and most crucially, the improvement in the quality of care for patients and their engagement with their care when leaders develop a culture of kindness and respect.

Levamisole derivatives as immune modulators for the treatment of amyotrophic lateral sclerosis (ALS).

Aim: To discover derivatives of the anthelmintic drug levamisole, which has been reported to possess immune-modulatory properties, as treatments for amyotrophic lateral sclerosis (ALS), which has been suggested to be in part an autoimmune disease. Results: We have synthesized ten analogs of the racemic version of levamisole, tetramisole, as well as eleven analogs on a related system. All of the analogs have been tested for their ability to affect the response of five ALS-relevant cytokines. Conclusion: We have discovered a number of interesting derivatives that have encouraging cytokine response data and good metabolic stability, with the potential to have a positive impact on ALS either as single agents, or in combination.

Aim: To discover derivatives of the antiparasitic worm drug levamisole, which has been reported to be able to modulate the immune response, as treatments for amyotrophic lateral sclerosis (ALS), which has been suggested to be in part an autoimmune disease. Results: We have synthesized ten analogs of a variation of levamisole, tetramisole, as well as 11 analogs on a related system. All of the analogs have been tested for their ability to affect the response of five ALS-relevant immune-modulatory substances (cytokines). Conclusion: We have discovered a number of interesting derivatives that have encouraging cytokine response data and good metabolic stability, with the potential to have a positive impact on ALS either as single agents, or in combination.

Novel pathogenic variants in Tubulin Tyrosine Like 5 (TTLL5) associated with cone-dominant retinal dystrophies and an abnormal optical coherence tomography phenotype.

Purpose: Autosomal recessive cone and cone-rod dystrophies (CD/CRD) are inherited forms of vison loss. Here, we report on and correlate the clinical phenotypes with the underlying genetic mutations. Methods: Clinical information was collected from subjects, including a family history with a chart review. They underwent a full ophthalmic examination, including best-corrected visual acuity, direct and indirect ophthalmoscopy, color vision testing, color fundus photography, contrast sensitivity, autofluorescence, and spectral domain-optical coherence tomography (SD-OCT), and full-field electroretinography. Next-generation panel-based genetic testing was used to identify DNA variants in subject buccal swab samples. Results: Genetic testing in two patients revealed three novel variants in the TTLL5 gene associated with CD/CRD: two missense variants (c.1433G>A;p.(Arg478Gln), c.241C>G;p.(Leu81Val), and one loss-of-function variant (c.2384_2387del;p.(Ala795Valfs*9). Based on in-silico analysis, structural modeling, and comparison to previously reported mutations, these novel variants are very likely to be disease-causing mutations. Combining retinal imaging with SD-OCT analysis, we observed an unusual sheen in the CD/CRD phenotypes. Conclusion: Based on the protein domain location of novel TTLL5 variants and the localization of TTLL5 to the connecting cilium, we conclude that the CD/CRD disease phenotype is characterized as a ciliopathy caused by protein tracking dysfunction. This initially affects cone photoreceptors, where photoreceptor cilia express a high level of TTLL5, but extends to rod photoreceptors over time. Fundus photography correlated with SD-OCT imaging suggests that the macular sheen characteristically seen with TTLL5 mutations derives from the photoreceptor's outer segments at the posterior pole.

Rectal sparing in prostate radiotherapy with combination-brachytherapy and hydrogel spacer.

BACKGROUND: Though some techniques that facilitate rectal sparing such as brachytherapy and intensity modulated radiotherapy (IMRT) have been examined in detail, technical aspects of hydrogel spacer (HS) have been studied less exhaustively. We examined HS quality metrics and approaches to placement for superior dosimetric outcomes. MATERIALS AND METHODS: A single site retrospective review of radiation plans was conducted for patients who received combination-brachytherapy (CBT) with 90 Gy low-dose-rate implant followed by external beam radiotherapy (45 Gy/25 fractions) with operating room (OR) placed HS (2017-2021). A randomly selected set of patients that received CBT without HS over the same time period was used for comparison. Dosimetric outcomes included D1cc and D5% rectum. Dose gradients were quantified. Student's t-test was used for statistical comparisons. RESULTS: Sixty patients (30 with and 30 without HS) who received CBT for prostate cancer were examined. Those with HS had lower mean D1cc [65.31 Gy (SD = 13.53)] and D5% [53.20 Gy (SD = 10.18)] compared to those treated without HS [91.67 Gy (SD = 8.31) and 75.00 Gy (SD = 8.45), respectively, p < 0.001]. Patients with superior HS (average thickness ≥1 cm; n = 12) had lower mean D1cc [58.49 Gy (SD = 13.25, p = 0.026)] and D5% [48.69 Gy (SD = 9.85, p = 0.049)] than those with thinner HS. When dose gradients were considered, HS spanning the interface between the prostate and perirectal tissues to a thickness ≥1 cm can reduce rectal maximum dose to 50-60 Gy. CONCLUSIONS: Through effective use of CBT and HS, extreme rectal dose restriction is possible. The goal for HS placement should be thickness ≥1 cm from base to apex.

Linkage analysis identifies an isolated strabismus locus at 14q12 overlapping with FOXG1 syndrome region.

Strabismus is a common condition, affecting 1%-4% of individuals. Isolated strabismus has been studied in families with Mendelian inheritance patterns. Despite the identification of multiple loci via linkage analyses, no specific genes have been identified from these studies. The current study is based on a seven-generation family with isolated strabismus inherited in an autosomal dominant manner. A total of 13 individuals from a common ancestor have been included for linkage analysis. Among these, nine are affected and four are unaffected. A single linkage signal has been identified at an 8.5 Mb region of chromosome 14q12 with a multipoint LOD (logarithm of the odds) score of 4.69. Disruption of this locus is known to cause FOXG1 syndrome (or congenital Rett syndrome; OMIM #613454 and *164874), in which 84% of affected individuals present with strabismus. With the incorporation of next-generation sequencing and in-depth bioinformatic analyses, a 4 bp non-coding deletion was prioritised as the top candidate for the observed strabismus phenotype. The deletion is predicted to disrupt regulation of FOXG1, which encodes a transcription factor of the Forkhead family. Suggestive of an autoregulation effect, the disrupted sequence matches the consensus FOXG1 and Forkhead family transcription factor binding site and has been observed in previous ChIP-seq studies to be bound by Foxg1 in early mouse brain development. Future study of this specific deletion may shed light on the regulation of FOXG1 expression and may enhance our understanding of the mechanisms contributing to strabismus and FOXG1 syndrome.

Photoreceptor precursor cell integration into rodent retina after treatment with novel glycopeptide PKX-001.

Cell replacement therapy is emerging as an important approach in novel treatments for neurodegenerative diseases. Many problems remain, in particular improvements are needed in the survival of transplanted cells and increasing functional integration into host tissue. These problems arise because of immune rejection, suboptimal precursor cell type, trauma during cell transplantation, and toxic compounds released by dying tissues and nutritional deficiencies. We recently developed an ex vivo system to facilitate identification of factors contributing to the death of transplanted neuronal (photoreceptor) and showed 2.8-fold improvement in transplant cell survival after pretreatment with a novel glycopeptide (PKX-001). In this study, we extended these studies to look at cell survival, maturation, and functional integration in an in vivo rat model of rhodopsin-mutant retinitis pigmentosa causing blindness. We found that only when human photoreceptor precursor cells were preincubated with PKX-001 prior to transplantation, did the cells integrate and mature into cone photoreceptors expressing S-opsin or L/M opsin. In addition, ribbon synapses were observed in the transplanted cells suggesting they were making synaptic connections with the host tissue. Furthermore, optokinetic tracking and electroretinography responses in vivo were significantly improved compared to cell transplants without PKX-001 pre-treatment. These data demonstrate that PKX-001 promotes significant long-term stem cell survival in vivo, providing a platform for further investigation towards the clinical application to repair damaged or diseased retina.

Investigating microglia during motor neuron degeneration using a zebrafish model.

Many different types of pathologies can arise in the central nervous system (CNS), such as neurodegeneration. The incidence of neurodegenerative diseases continues to increase, yet the pathogenesis underlying most neurodegenerative diseases, notably in amyotrophic lateral sclerosis (ALS), remains elusive. Neuronal support cells, or glia, are known to play a crucial role in ALS. Microglia are the resident immune cells of the CNS and also have neurotrophic support functions. These cells have a disease-modifying function in ALS, yet this role is not well understood. A likely reason for this is that the intact CNS is particularly challenging to access for investigation in patients and in most animal models, which has impeded research in this field. The zebrafish is emerging as a robust model system to investigate cells in vivo, and offer distinct advantages over other vertebrate models for investigating neurodegenerative diseases. Live imaging in vivo is a powerful technique to characterize the role of dynamic cells such as microglia during neurodegeneration, and zebrafish provide a convenient means for live imaging. Here, we discuss the zebrafish as a model for live imaging, provide a brief overview of available high resolution imaging platforms that accommodate zebrafish, and describe our own in vivo studies on the role of microglia during motor neuron degeneration. Live in vivo imaging is anticipated to provide invaluable advancements to defining the pathogenesis underlying neurodegenerative diseases, which may in turn allow for more specifically targeted therapeutics.

RNA-based therapies in animal models of Leber congenital amaurosis causing blindness.

Leber congenital amaurosis (LCA) is a severe, genetically heterogeneous recessive eye disease in which ~ 35% of gene mutations are in-frame nonsense mutations coding for loss-of-function premature termination codons (PTCs) in mRNA. Nonsense suppression therapy allows read-through of PTCs leading to production of full-length protein. A limitation of nonsense suppression is that nonsense-mediated decay (NMD) degrades PTC-containing RNA transcripts. The purpose of this study was to determine whether inhibition of NMD could improve nonsense suppression efficacy in vivo. Using a high-throughput approach in the recessive cep290 zebrafish model of LCA (cep290;Q1223X), we first tested the NMD inhibitor Amlexanox in combination with the nonsense suppression drug Ataluren. We observed reduced retinal cell death and improved visual function. With these positive data, we next investigated whether this strategy was also applicable across species in two mammalian models: Rd12 (rpe65;R44X) and Rd3 (rd3;R107X) mouse models of LCA. In the Rd12 model, cell death was reduced, RPE65 protein was produced, and in vivo visual function testing was improved. We establish for the first time that the mechanism of action of Amlexanox in Rd12 retina was through reduced UPF1 phosphorylation. In the Rd3 model, however, no beneficial effect was observed with Ataluren alone or in combination with Amlexanox. This variation in response establishes that some forms of nonsense mutation LCA can be targeted by RNA therapies, but that this needs to be verified for each genotype. The implementation of precision medicine by identifying better responders to specific drugs is essential for development of validated retinal therapies.

An update on the genetics of ocular coloboma.

Ocular coloboma is an uncommon, but often severe, sight-threatening condition that can be identified from birth. This congenital anomaly is thought to be caused by maldevelopment of optic fissure closure during early eye morphogenesis. It has been causally linked to both inherited (genetic) and environmental influences. In particular, as a consequence of work to identify genetic causes of coloboma, new molecular pathways that control optic fissure closure have now been identified. Many more regulatory mechanisms still await better understanding to inform on the development of potential therapies for patients with this malformation. This review provides an update of known coloboma genes, the pathways they influence and how best to manage the condition. In the age of precision medicine, determining the underlying genetic cause in any given patient is of high importance.

Prospects and modalities for the treatment of genetic ocular anomalies.

Over the last three decades, genetic studies have made great strides toward the identification of genes and genetic mechanisms underlying congenital disorders of the eye. However, despite the vast knowledge available this has not translated into treatments to prevent or repair the damage in the clinical setting. Recently, new research in technologies, such as tissue regeneration, next generation designer drugs, and genome editing, have become available for some genetic disorders that might be applicable to congenital ocular diseases in the near future. Here, we provide an overview of the emerging therapeutic modalities and the future prospects they hold for debilitating ocular defects.

Cell Death Pathways in Mutant Rhodopsin Rat Models Identifies Genotype-Specific Targets Controlling Retinal Degeneration.

Retinitis pigmentosa (RP) is a group of inherited neurological disorders characterized by rod photoreceptor cell death, followed by secondary cone cell death leading to progressive blindness. Currently, there are no viable treatment options for RP. Due to incomplete knowledge of the molecular signaling pathways associated with RP pathogenesis, designing therapeutic strategies remains a challenge. In particular, preventing secondary cone photoreceptor cell loss is a key goal in designing potential therapies. In this study, we identified the main drivers of rod cell death and secondary cone loss in the transgenic S334ter rhodopsin rat model, tested the efficacy of specific cell death inhibitors on retinal function, and compared the effect of combining drugs to target multiple pathways in the S334ter and P23H rhodopsin rat models. The primary driver of early rod cell death in the S334ter model was a caspase-dependent process, whereas cone cell death occurred though RIP3-dependent necroptosis. In comparison, rod cell death in the P23H model was via necroptotic signaling, whereas cone cell loss occurred through inflammasome activation. Combination therapy of four drugs worked better than the individual drugs in the P23H model but not in the S334ter model. These differences imply that treatment modalities need to be tailored for each genotype. Taken together, our data demonstrate that rationally designed genotype-specific drug combinations will be an important requisite to effectively target primary rod cell loss and more importantly secondary cone survival.

Loss-of-function mutations in KIF14 cause severe microcephaly and kidney development defects in humans and zebrafish.

Mutations in KIF14 have previously been associated with either severe, isolated or syndromic microcephaly with renal hypodysplasia (RHD). Syndromic microcephaly-RHD was strongly reminiscent of clinical ciliopathies, relating to defects of the primary cilium, a signalling organelle present on the surface of many quiescent cells. KIF14 encodes a mitotic kinesin, which plays a key role at the midbody during cytokinesis and has not previously been shown to be involved in cilia-related functions. Here, we analysed four families with fetuses presenting with the syndromic form and harbouring biallelic variants in KIF14. Our functional analyses showed that the identified variants severely impact the activity of KIF14 and likely correspond to loss-of-function mutations. Analysis in human fetal tissues further revealed the accumulation of KIF14-positive midbody remnants in the lumen of ureteric bud tips indicating a shared function of KIF14 during brain and kidney development. Subsequently, analysis of a kif14 mutant zebrafish line showed a conserved role for this mitotic kinesin. Interestingly, ciliopathy-associated phenotypes were also present in mutant embryos, supporting a potential direct or indirect role for KIF14 at cilia. However, our in vitro and in vivo analyses did not provide evidence of a direct role for KIF14 in ciliogenesis and suggested that loss of kif14 causes ciliopathy-like phenotypes through an accumulation of mitotic cells in ciliated tissues. Altogether, our results demonstrate that KIF14 mutations result in a severe syndrome associating microcephaly and RHD through its conserved function in cytokinesis during kidney and brain development.

Hidden morbidity: The results of a collaborative community chronic obstructive pulmonary disease screening initiative.

Chronic obstructive pulmonary disease (COPD) often goes unrecognised resulting in people living with the disease without a diagnosis. We investigated the characteristics, symptom burden and flow of participants in a community COPD screening initiative. Screening was undertaken during four events over 2-weeks. Participants completed symptom questionnaires and FEV-1/FEV-6 measurement. Patients with FEV-1 <80% predicted or FEV-1 ≥ 80% predicted and FEV-1/FEV-6 <0.72 were considered 'screen-positive' and invited to attend a 1-stop diagnostic clinic. Two hundred and fifty-seven individuals participated (mean ± SD age 58 ± 16, 24% current smokers). Seventy-seven were screen-positive with 27 ultimately attending a 1-stop clinic and 18 having confirmed COPD. The CAT score of participants with COPD was 19.3 ± 11.4. Two-thirds had moderate airflow obstruction on spirometry. The diagnosis rate in this screening initiative was comparable to trials of systematic case finding. Further research is required to explore the broader clinical impact of COPD screening.

Animal models of amyotrophic lateral sclerosis: A comparison of model validity.

Animal models are necessary to investigate the pathogenic features underlying motor neuron degeneration and for therapeutic development in amyotrophic lateral sclerosis (ALS). Measures of model validity allow for a critical interpretation of results from each model and caution from over-interpretation of experimental models. Face and construct validity refer to the similarity in phenotype and the proposed causal factor to the human disease, respectively. More recently developed models are restricted by limited phenotype characterization, yet new models hold promise for novel disease insights, thus highlighting their importance. In this article, we evaluate the features of face and construct validity of our new zebrafish model of environmentally-induced motor neuron degeneration and discuss this in the context of current environmental and genetic ALS models, including C9orf72, mutant Cu/Zn superoxide dismutase 1 and TAR DNA-binding protein 43 mouse and zebrafish models. In this mini-review, we discuss the pros and cons to validity criteria in each model. Our zebrafish model of environmentally-induced motor neuron degeneration displays convincing features of face validity with many hallmarks of ALS-like features, and weakness in construct validity. However, the value of this model may lie in its potential to be more representative of the pathogenic features underlying sporadic ALS cases, where environmental factors may be more likely to be involved in disease etiology than single dominant gene mutations. It may be necessary to compare findings between different strains and species modeling specific genes or environmental factors to confirm findings from ALS animal models and tease out arbitrary strain- and overexpression-specific effects.

The Impact of Scripted Pain Education on Patient Satisfaction in Outpatient Abdominal Surgery Patients.

PURPOSE: Practice guidelines for acute pain management in perioperative patients recommend providing consistent perioperative pain education that includes medication and behavioral techniques to control pain. However, literature indicates that most nurses deliver patient education based on personal preferences, time limitations, and availability of teaching aids. The purpose of this study was to evaluate patient satisfaction with scripted preoperative pain management education for patients undergoing outpatient abdominal surgery. DESIGN: A pretest and posttest design compared patient perceptions of and satisfaction with pain management education before and after the introduction of scripted education. METHODS: An independent t test was applied to measure differences between groups. FINDINGS: The postscripting group responses indicated that pain education was helpful in managing postoperative pain at a significant (P = 0.03) level. CONCLUSIONS: Use of scripted dialog, along with specific written patient education, has a positive impact on postoperative patient satisfaction with pain management.

Anolis carolinensis as a model to understand the molecular and cellular basis of foveal development.

The fovea is an anatomical specialization of the central retina containing closely packed cone-photoreceptors providing an area of high acuity vision in humans and primates. Despite its key role in the clarity of vision, little is known about the molecular and cellular basis of foveal development, due to the absence of a foveal structure in commonly used laboratory animal models. Of the amniotes the retina in birds of prey and some reptiles do exhibit a typical foveal structure, but they have not been studied in the context of foveal development due to lack of availability of embryonic tissue, lack of captive breeding programs, and limited genomic information. However, the genome for the diurnal bifoveate reptile species Anolis carolinensis (green anole) was recently published and it is possible to collect embryos from this species in captivity. Here, we tested the feasibility of using the anole as a model to study foveal development. Eyes were collected at various stages of development for histological analysis, immunofluorescence, and apoptosis. We show that at embryonic stage (ES) 10 there is peak ganglion cell density at the incipient central foveal region and a single row of cone photoreceptor nuclei. At ES17 the foveal pit begins to form and at this stage there are 3-4 rows of cone nuclei. Post-hatching a further increase in cone density and lengthening of inner and outer segments is observed. A yellowish pigment was seen in the adult central foveal region, but not in the temporal fovea. At ES14 Pax6 was localized across the entire retina, but was more prominent in the ganglion cell layer (GCL) and the part of the inner nuclear layer (INL) containing amacrine cell bodies. However, at ES17 Pax6 expression in the ganglion cells of the central retina was markedly reduced. Bioinformatic analysis revealed that 86% of human candidate foveal hypoplasia genes had an orthologous gene or DNA sequence in the green anole. These findings provide the first insight into foveal morphogenesis in the green anole and suggest that it could be a very useful model for investigating the molecular signals driving foveal development, and thus inform on human foveal development and disease.

Modeling Environmentally-Induced Motor Neuron Degeneration in Zebrafish.

Zebrafish have been used to investigate motor neuron degeneration, including as a model system to examine the pathogenesis of amyotrophic lateral sclerosis (ALS). The use of zebrafish for this purpose has some advantages over other in vivo model systems. In the current paper, we show that bisphenol A (BPA) exposure in zebrafish embryos results in motor neuron degeneration with affected motor function, reduced motor axon length and branching, reduced neuromuscular junction integrity, motor neuron cell death and the presence of activated microglia. In zebrafish, motor axon length is the conventional method for estimating motor neuron degeneration, yet this measurement has not been confirmed as a valid surrogate marker. We also show that reduced motor axon length as measured from the sagittal plane is correlated with increased motor neuron cell death. Our preliminary timeline studies suggest that axonopathy precedes motor cell death. This outcome may have implications for early phase treatments of motor neuron degeneration.

Correlation of novel PAX6 gene abnormalities in aniridia and clinical presentation.

OBJECTIVE: To describe the clinical presentation and genotype of subjects with aniridia with a particular focus on foveal hypoplasia. DESIGN: Prospective cohort study. PARTICIPANTS: Thirty-three Canadian participants with aniridia and of various ethnic backgrounds residing in British Columbia. METHODS: Full ophthalmic examinations and posterior segment spectral domain-optical coherence tomography (SD-OCT) imaging were performed. Foveal hypoplasia was graded independently by 2 staff ophthalmologists. PAX6 sequencing was performed and chromosomal 11p anomalies investigated. Candidate gene and single-nucleotide polymorphism sequencing in genes functionally related to PAX6 were also studied. RESULTS: Best corrected visual acuities in the cohort ranged from 0.0 logMAR to no light perception. Total absence of iris tissue was seen in the majority (42 of 66 eyes). In those in whom SD-OCT was possible, foveal hypoplasia was seen in the majority (45 of 56 eyes, 80%). Molecular genetic defects involving PAX6 were identified in 30 participants (91%), including 4 novel PAX6 mutations (Gly18Val; Ser65ProfsX14; Met337ArgfsX18; Ser321CysfsX34) and 4 novel chromosome 11p deletions inclusive of PAX6 or a known PAX6 regulatory region. CONCLUSIONS: The number of PAX6 mutations associated with aniridia continues to increase. Variable foveal architecture despite nearly identical anterior segment disease in 4 participants with an Ex9 ELP4-Ex4 DCDC1 deletion suggested that molecular cues causing variation in disease in the posterior segment differ from those at play in the anterior segment. Results in 3 patients without identifiable PAX6 mutations and a review of the literature suggest that such cases be described as phenocopies rather than actual cases of the syndrome of aniridia.