Secondary Data Analysis of Inflammation-Related mRNAs in Conjunctival Impression Cytology Samples of Aniridia Patients

PURPOSE

Aniridia is a rare corneal disease that is often associated with aniridia-associated keratopathy (AAK). In AAK, the conjunctival tissue crosses the limbal border, forming a corneal pannus that extends into the corneal center. With increasing AAK severity, corneal pannus formation, vascularization, and ocular surface inflammation increase. The purpose of this study was to investigate inflammation-related mRNA expression in conjunctival epithelial cells in AAK and its relationship with AAK severity.

METHODS

Using impression cytology, bulbar conjunctival cells were sampled from 20 subjects with congenital aniridia and 20 age-matched and sex-matched healthy control subjects. RNA was extracted, and mRNA analyses were performed using microarray, which was evaluated for inflammatory markers.

RESULTS

In the analyzed aniridia subjects, 70 deregulated mRNAs encoding proinflammatory or antiinflammatory cytokines or factors associated with chronic inflammation, including increased IL-1, IL-8, and MIP3A/CCL20 mRNA. The most downregulated mRNA was TIMP3, and the most upregulated mRNA was Protein c-Fos.Of the 70 mRNAs, 14 inflammation-related genes were altered only in the mild AAK forms, whereas only 2 mRNAs were altered only in the severe AAK forms (TLR4 and PPARG).

CONCLUSIONS

The expression of numerous proinflammatory and antiinflammatory cytokines is deregulated at the ocular surface of aniridia subjects with mild AAK. Thus, early antiinflammatory treatment may prevent or slow down corneal scarring and pannus formation in aniridia subjects.

Custom Iris Prosthesis for Subtotal Traumatic Aniridia From Combat Ocular Trauma

Traumatic aniridia from combat ocular trauma can cause visual disability. A 41-year-old male Army Veteran was referred for evaluation of light sensitivity and glare secondary to subtotal traumatic aniridia of his left eye from an improvised explosive device blast. A custom-made artificial iris prosthesis was implanted in the ciliary sulcus and secured using Gore-Tex sutures. After surgery, the patient reported improvement of his light sensitivity and quality of life. The custom iris prosthesis is a surgical option for visual disability resulting from traumatic aniridia from combat ocular trauma.

Co-Occurrence of Congenital Aniridia Due to Nonsense PAX6 Variant p.(Cys94*) and Chromosome 21 Trisomy in the Same Patient

This study aims to present a clinical case involving the unique co-occurrence of congenital aniridia and Down syndrome in a young girl and to analyze the combined impact of these conditions on the patient's phenotype. The investigation involved comprehensive pediatric and ophthalmological examinations alongside karyotyping and Sanger sequencing of the PAX6 gene. The patient exhibited distinctive features associated with both congenital aniridia and Down syndrome, suggesting a potential exacerbation of their effects. Cytogenetic and molecular genetic analysis revealed the presence of trisomy 21 and a known pathogenic nonsense variant in exon 6 of the PAX6 gene (c.282C>A, p.(Cys94*)) corresponding to the paired domain of the protein. The observation of these two hereditary anomalies offers valuable insights into the molecular pathogenetic mechanisms underlying each condition. Additionally, it provides a basis for a more nuanced prognosis of the complex disease course in this patient. This case underscores the importance of considering interactions between different genetic disorders in clinical assessments and treatment planning.

Isolated aniridia caused by a novel PAX6 heterozygous deletion mediated by multi-exon complex rearrangement

PURPOSE

Mutations in PAX6 gene (chromosome 11p13) encoding a transcriptional regulator involved in oculogenesis mostly present with aniridia. Aniridia is not uncommon in the Philippines but only limited information is available as yet. The purpose of this study was to present a novel, deletion mediated by complex rearrangement in PAX6 gene causing an isolated aniridia in a Filipino girl.

PATIENTS AND METHODS

The patient is an 8-year-old girl who came in due to leukocoria with associated nystagmus and esotropia. She presented with subnormal vision, nystagmus, aniridia, and cataractous lenses in both eyes. The family history reveals presence of the aniridia and cataract with the mother and a sibling. The patient underwent lens extraction without intraocular lens implantation bilaterally, where patient subsequently underwent intraocular lens implantation on her left eye. Systemic workup was performed including whole abdomen, renal ultrasound, blood chemistry, and urinalysis. Targeted cataract panel with WT1 and PAX6 genes revealed a novel, heterozygous PAX6-inherited mutation from the mother. This variant is a complex rearrangement in PAX6 involving partial deletions of exons 3-5, including the initiator codon. Deletions of PAX6 are part of a contiguous gene deletion syndrome - Wilms tumor, aniridia, genitourinary anomalies, and intellectual disability syndrome - and therefore evaluation of the WT1 gene was necessary to rule out this life-threatening syndrome.

CONCLUSION

This rare, complex rearrangement of multiple exons and deletions in PAX6 causing an isolated aniridia phenotype is probably the first reported case. The patient was managed by a multidisciplinary team and the guardians were counseled regarding the prognosis and complications.

Future directions in managing aniridia-associated keratopathy

Congenital aniridia is a panocular disorder that is typically characterized by iris hypoplasia and aniridia-associated keratopathy (AAK). AAK results in the progressive loss of corneal transparency and thereby loss of vision. Currently, there is no approved therapy to delay or prevent its progression, and clinical management is challenging because of phenotypic variability and high risk of complications after interventions; however, new insights into the molecular pathogenesis of AAK may help improve its management. Here, we review the current understanding about the pathogenesis and management of AAK. We highlight the biological mechanisms involved in AAK development with the aim to develop future treatment options, including surgical, pharmacological, cell therapies, and gene therapies.

[Congenital aniridia patients' experience on their visual impairment in Hungary.]

INTRODUCTION

Aniridia is a rare congenital panocular disease associated with varying degrees of visual acuity impairment.

OBJECTIVE

To assess the experiences of congenital aniridia patients in Hungary, with visual impairment using a questionnaire developed by the ANIRIDIA-NET.

PATIENTS AND METHOD

Patients completed the Hungarian version of the 20-item ANIRIDIA-NET questionnaire with our assistance. The questionnaire covered demographic data, the most common complaints caused by the disease, the difficulties caused by low vision in different life situations and the frequency of low vision aids used in daily life.

RESULTS

33 subjects (17 female [51.51%] and 16 male [48.48%]), 16 (48.5%) children and 17 (51.5%) adults completed the questionnaire, with an age of 25.69 ± 17.49 years (5-59 years). Daily photosensitivity was reported by 27 (81.8%), dry eyes by 5 (15.2%), tearing by 4 (12.1%), fluctuating vision by 3 (9.1%), and eye pain by 2 (6.1%) subjects. The majority of respondents said that personal communication with schoolmates (16 [48.5%]) or colleagues at work (11 [33.3%]) never caused difficulties because of their visual impairment. 29 people (87.9%) never needed help with daily routines at home, 24 (72.7%) with getting to school/work and 17 (51.5%) with various activities. 29 people (87.8%) never used low vision aids for communication, 23 (69.7%) for travelling, 20 (60.6%) for participating in social activities, 18 (54.5%) for studying/work.

CONCLUSION

Although aniridia is associated with reduced visual acuity, the majority of people with congenital aniridia, especially in childhood, manage to cope with personal communication and various life situations without difficulty, despite their eye complaints. Low vision aids can be an important aid for them as they grow into adulthood and as they age. Orv Hetil. 2023; 164(34): 1342-1349.

A novel missense variant expands the phenotype and genotype of PAX6-associated foveal hypoplasia accompanied by various manifestations of anterior segment dysgenesis

BACKGROUND

According to previous reports, PAX6-associated foveal hypoplasia (FH) could usually be accompanied by various anterior segment anomalies including variable iris changes. This study aims to exhibit unusual phenotypes of a novel missense variant of PAX6 from a Chinese pedigree.

METHODS

Ophthalmic examinations including slit-lamp biomicroscopy, gonioscopy, ophthalmic ultrasound, ultrasonic biomicroscopy, optical coherence tomography, wide-field fundus imaging, and visual field test were performed to evaluate the clinical manifestations. Whole-exome sequencing (WES) and bioinformatics analysis were conducted in eight members from this pedigree to identify the causative mutation.

RESULTS

WES revealed a novel heterozygous substitution of PAX6 (NM_000280.5:c.157G > A, p.(Val53Met) (chr11:31823309 C > T, hg19)), which cosegregated with the phenotype of this pedigree. All the three patients (a pair of fraternal twins and their mother) exhibited bilateral FH and anterior segment dysgenesis (ASD) including microcornea, sclerocornea, obvious symmetrical corectopia, iris stromal dysplasia, goniodysgenesis, and abnormal distribution of fundus blood vessels. The girl of the fraternal twins also demonstrated bilateral temporal deviation of lenses and abnormal tissue membrane connecting anterior chamber angle and lens anterior capsule in the right eye. The mother additionally showed apparent cataract bilaterally and cupping of the optic disc in her left eye.

CONCLUSION

A novel missense variant in PAX6 gene was detected in a Chinese pedigree demonstrating bilateral FH and ASD. It is really distinctive that the ASD involves almost all parts of the anterior segment, and bilateral symmetrical corectopia is the most perceptible sign. This study expands the phenotypic and genotypic spectrum of PAX6-associated ocular diseases, and facilitates the understanding of the crucial role that PAX6 plays in the development of the eye. Meanwhile, PAX6 could be considered as a candidate pathogenic gene of bilateral symmetrical corectopia.

A novel PAX6 variant as the cause of aniridia in a Chinese patient with SRRRD

BACKGROUND

The genotype characteristics and their associated clinical phenotypes in patients with aniridia were analyzed to explore pathogenic variants using whole-exome sequencing.

METHODS

One patient with aniridia was enrolled at the Beijing Tongren Hospital. Comprehensive ophthalmic and general examinations were performed on the patient. DNA was extracted from the patient, and whole-exome sequencing was performed to identify the causative variant. The pathogenicity of the variant was predicted using in silico analysis and evaluated according to American College of Medical Genetics and Genomics guidelines. Relationships between genetic variants and clinical features were analyzed.

RESULTS

In addition to the classical aniridia phenotype showing complete iris aplasia, foveal hypoplasia, and ectopic lentis, the patient also exhibited spontaneous reattachment rhegmatogenous retinal detachment (SRRRD). Whole-exome sequencing identified a novel heterozygous variant, exon8:c.640_646del:p.R214Pfs*28.

CONCLUSIONS

The present study broadens the range of genetic variants described in aniridia and presents an aniridia patient with SRRRD.

Aniridic scleral fixation of intraocular lens: The answer to vision loss with photophobia!

Background

Aniridia is defined as missing iris tissue which can be partial, subtotal, or total. Characteristic clinical symptoms include photophobia and decreased visual acuity due to an increased light perception. In addition to this, disturbing cosmetic problems are prevalent. Even after implantation of an intraocular lens, patients often tend to be unsatisfied.

Purpose

The answer to this problem lies in the implantation of an aniridic scleral fixation of intraocular lens (SFIOL), which has a central optical axis that acts as the refractive lens and a peripheral rim of a hyperpigmented area that mimics the iris and hence reduces photophobia. The purpose of the video was to demonstrate the use of black diaphragm intraocular lens (BDIOL) implantation, its surgical steps, and its outcomes.

Synopsis

We report one such case where a young patient presented with post-traumatic aniridia with subluxated total cataract and spillover vitreous hemorrhage. He was subjected to a vitrectomy, cataract removal, and placement of an aniridic SFIOL with prolene 9-0 using the four-point fixation method. This gave an extremely gratifying outcome and solved both problems, that is, vision and photophobia. Highlight: Before implantation of the SFIOL, the patients had reduced visual acuity from aphakia and intolerable glare from aniridia. In this case-based approach and with relevant example, we tried to provide a solution for tricky scenarios like co-existing traumatic cataract and traumatic aniridia. The patient showed improved visual acuity and marked glare reduction after black diaphragm SFIOL implantation.

Video link

https://youtu.be/atl60WetFsM.

Pediatric glaucoma in aniridia in a population of Egyptian children

PURPOSE

To report on the incidence, characteristics, and treatment of glaucoma in association with aniridia in a population of Egyptian children.

METHODS

A retrospective chart review was conducted of children (<18 years of age) presenting with aniridia between 2007 and 2022. Diagnosis of glaucoma was based on cup:disk ratio (>0.3) and IOP (>16 mm Hg). Success of glaucoma surgery was defined as IOP ≤16 mm Hg and stable or regressing cup:disk ratio.

RESULTS

A total of 93 eyes of 47 children were included. The mean patient age at presentation was 41.2 ± 44.7 months. The mean intraocular pressure (IOP), corneal diameter, cup:disk ratio, and axial length on presentation were 16.4 ± 10.3 mm Hg, 11.4 ± 1.3 mm, 0.4 ± 0.3, and 22.43 ± 2.6 mm Hg. Of eyes with IOP and cup:disk ratio data at presentation, 23 (30%) were diagnosed with glaucoma. Fourteen eyes underwent surgery after presentation; follow-up data were available for half the remaining eyes. At the final follow-up, glaucoma was present in 20 eyes (49%). Glaucoma surgery was performed in 17 eyes, with a complete or qualified success rate of 82.4% at final follow-up, with 15 eyes having at least 12 months' follow-up.

CONCLUSIONS

In this study cohort, children with aniridia presented at around 3 years of age, with glaucoma at presentation in almost one-third of the cases.

Report on the 2021 Aniridia North America symposium on PAX6, aniridia, and beyond

The inaugural Aniridia North America (ANA) Symposium was held on the first weekend in November 2021 in Charlottesville, VA, at the University of Virginia. The purpose of this meeting was to bring together an international group of scientists, physicians, patient advocacy groups, and individuals with aniridia to discuss recent advances in knowledge about aniridia and other congenital eye diseases and the development of potential treatments for congenital eye disorders using personalized medicine. Leaders in several areas of eye research and clinical treatment provided a broad perspective on new research advances that impact an understanding of the causes of the damage to the eye associated with aniridia and the development of novel treatments for this and related disorders. Here we summarize the research discussed at the symposium.

Genetic predisposition to ocular surface disorders and opportunities for gene-based therapies

The ocular surface, comprised of the corneal and conjunctival epithelium, innervation system, immune components, and tear-film apparatus, plays a key role in ocular integrity as well as comfort and vision. Gene defects may result in congenital ocular or systemic disorders with prominent ocular surface involvement. Examples include epithelial corneal dystrophies, aniridia, ectrodactyly-ectodermal dysplasia-clefting (EEC) syndrome, xeroderma pigmentosum (XP), and hereditary sensory and autonomic neuropathy. In addition, genetic factors may interact with environmental risk factors in the development of several multifactorial ocular surface disorders (OSDs) such as autoimmune disorders, allergies, neoplasms, and dry eye disease. Advanced gene-based technologies have already been introduced in disease modelling and proof-of-concept gene therapies for monogenic OSDs. For instance, patient-derived induced pluripotent stem cells have been used for modelling aniridia-associated keratopathy (AAK), XP, and EEC syndrome. Moreover, CRISPR/Cas9 genome editing has been used for disease modelling and/or gene therapy for AAK and Meesmann's epithelial corneal dystrophy. A better understanding of the role of genetic factors in OSDs may be helpful in designing personalized disease models and treatment approaches. Gene-based approaches in monogenic OSDs and genetic predisposition to multifactorial OSDs such as immune-mediated disorders and neoplasms with known or possible genetic risk factors has been seldom reviewed. In this narrative review, we discuss the role of genetic factors in monogenic and multifactorial OSDs and potential opportunities for gene therapy.

Outcomes of Human Leukocyte Antigen-Matched Allogeneic Cultivated Limbal Epithelial Transplantation in Aniridia-Associated Keratopathy-A Single-Center Retrospective Analysis

PURPOSE

To assess the efficacy and safety of human leukocyte antigen-matched allogeneic cultivated limbal epithelial stem cell grafts in the treatment of aniridia-associated keratopathy (AAK).

METHODS

Six eyes of 6 patients with severe AAK received an allogeneic stem cell graft between January 2010 and March 2017. Anatomical and functional results were assessed at 6 months, 1 year, 2 years, and the final follow-up visit available. Safety analysis was performed by considering all perioperative and postoperative adverse events and additional surgeries required during the follow-up period.

RESULTS

The mean follow-up was 53.6 months (range 24-104 months). In most patients (80%), there was an early improvement of the keratopathy postoperatively, which slowly regressed during longer follow-up. At the final follow-up, 4 of the eyes were graded as failure and 1 eye was graded as partial success. Grading the sixth eye was not possible because of an adverse event. None of the patients maintained a total anatomical success in the long-term. Only 1 patient maintained a modest improvement in best-corrected visual acuity from hand motion to counting fingers. Four serious adverse events were recorded in 2 patients.

CONCLUSIONS

Severe AAK remains a challenging condition to manage. Transplantation of allogenic ex vivo cultivated limbal stem cells may provide a temporary improvement in ocular surface stability, but anatomical and functional results are poor in the long-term. The eyes are prone to adverse events, and any surgical treatment should take this into consideration.

Management of Congenital Aniridia-Associated Keratopathy: Long-Term Outcomes from a Tertiary Referral Center

PURPOSE

To report the outcomes of medical and surgical management for congenital aniridia-associated keratopathy (AAK) over a long-term follow-up period.

DESIGN

Retrospective, comparative case series.

METHODS

Medical records of patients diagnosed with congenital aniridia were retrospectively reviewed. Age, sex, ethnicity, follow-up time, AAK stage, noncorneal abnormalities, ocular surgeries, and complications were recorded. The visual acuity equivalent (VAE), approximate Early Treatment Diabetic Retinopathy Study (appETDRS) letter score, was calculated using recorded Snellen visual acuities.

RESULTS

A total of 92 eyes of 47 patients (31 females) with mean age of 48.0 ± 18.0 years and mean follow-up of 78.6 ± 42.2 months were included. At the initial visit, 12 eyes (13%) were classified as Stage I AAK, 33 eyes (35.9%) were Stage II, 25 eyes (27.2%) were Stage III, 17 eyes (18.5%) were Stage IV, and 5 eyes (5.4%) were Stage V. Limbal stem cell transplantation (LSCT) and Boston keratoprosthesis (KPro) were frequently performed in eyes with Stages III-V. These advanced corneal surgeries significantly improved the median (95% confidence interval [CI]) of calculated appETDRS scores from 2 (0-20) to 26 (15-41) (Snellen values, 20/20,000 to 20/300; P = 0.0004). Patients with earlier Stages (I-II) of AAK were managed medically and had stable visual acuity through their final visits (appETDRS score of 26 [20-35] to 35 [26-35]; Snellen, 20/300 to 20/200; P > 0.05). The appETDRS VAE was significantly improved from 20 (0-35) to 30 (20-55), Snellen, 20/400 to 20/250, following LSCT (P = 0.021) and from 2 (0-20) to 2 (0-41) after KPro; Snellen, 20/20,000 VAE but with improved 95% CI after follow-up (P = 0.019).

CONCLUSIONS

With proper characterization and staging of AAK, individualized medical and advanced surgical interventions preserves and improves visual acuity.

Deletion distal to the PAX6 coding region reveals a novel basis for familial cosegregation of aniridia and diabetes mellitus

AIMS

Analyze cosegregation of aniridia and diabetes to identify genetic criteria for detection and early treatment of diabetes-susceptible aniridia patients.

METHODS

We assessed a two-generation family: three individuals with aniridia, two previously diagnosed as type 2 diabetes. One individual with aniridia, with unknown diabetes status, was evaluated by oral glucose tolerance test. Genetic analysis of aniridia-associated genes was performed on all available family members. Candidate genes were functionally tested by gene silencing in MIN6 pancreatic β-cells.

RESULTS

A 25 year old male with aniridia had a diabetic oral glucose tolerance test despite a normal fasting blood glucose. A 484-630 kb deletion ∼120 kb distal to PAIRED BOX 6 (PAX6) showed dominant cosegregation with aniridia and diabetes in all affected family members. The deleted region contains regulatory elements for PAX6 expression and four additional coding regions. Knockdown of two of the deleted genes (Dnajc24 or Immp1l) with Pax6 impaired glucose-stimulated insulin secretion.

CONCLUSIONS

We demonstrate dominant cosegregation of diabetes and aniridia with a deletion distal to PAX6, which is clinically distinct from the mild glucose intolerance previously reported with PAX6 coding mutations. Asymptomatic aniridia individuals appear at risk of diabetes (and its complications) and could benefit from earlier diagnosis and treatment.

Molecular analysis of Cypriot families with aniridia reveals a novel PAX6 mutation

The present study investigated the clinical and mutational spectrum of aniridia in a cohort of 17 affected individuals from six families from Cyprus. Each proband was initially evaluated for copy number variants at the PAX6 locus and subsequently underwent PAX6 mutation screening. Sequence analysis of FOXC1 and PITX2 was performed in patients who did not carry a PAX6 mutation. The most common clinical features in the group of aniridia patients associated with aniridia were nystagmus, cataracts and glaucoma. PAX6 pathogenic mutations were identified in five out of six families (a diagnostic yield of 84%). Previously reported pathogenic mutations in PAX6 were identified in four families, which comprise p.R203*, p.R240* and p.R317*. In addition, a novel pathogenic variant (p.E220Gfs*23) was identified in a single family. No pathogenic mutations were detected in PAX6, FOXC1 or PITX2 in the only patient with a sporadic form of aniridia‑like phenotype, confirming the genetic heterogeneity associated with this disease. To the best of our knowledge this is the first report on the mutational spectrum of PAX6 in aniridia patients of Cypriot ancestry. Mutational screening of PAX6 serves a crucial role in distinguishing isolated from syndromic forms of aniridia, and it may therefore eliminate the need for renal ultrasound scan surveillance, delineate the phenotype and improve genetic counseling.

No Light Perception Outcomes Following Boston Keratoprosthesis Type 1 Surgery

PURPOSE

To determine the incidence rate, principal causes, and clinical course of eyes developing no light perception (NLP) visual acuity (VA) following Boston Keratoprosthesis (B-KPro) type 1 surgery. Secondary objectives include determining the incidence rate, relative risk (RR), and survival probability with respect to NLP outcomes among eyes with congenital aniridia.

DESIGN

Retrospective, interventional case series.

SUBJECTS

All patients undergoing B-KPro type 1 surgery between October 2008 and June 2016 by a single surgeon at CHUM - Hôpital Notre-Dame.

METHODS

Records of patients having undergone B-KPro implantation were reviewed. Eyes with a final outcome of NLP were further reviewed to determine best recorded postoperative VA, time to NLP onset, clinical course, and principal cause. Descriptive statistics, incidence rates, Kaplan-Meier survival curves, and the RR of NLP outcomes among eyes with aniridia were determined. Statistical significance was defined as P < .05.

RESULTS

Records of 119 patients were included, with an average follow-up of 49.1 ± 26.8 months postoperatively. Nineteen eyes had a final outcome of NLP, representing 16.0%. The incidence rate of NLP was 0.04 cases per eye-year of follow-up. The most common principal causes were inoperable retinal detachment (n = 7, 36.8%), terminal glaucoma (n = 6, 31.6%), and carrier graft melt-related complications (n = 5, 26.3%). The RR of developing NLP among eyes with aniridia was 3.04 (P = .01).

CONCLUSIONS

No light perception is a devastating but uncommon outcome of B-KPro surgery. Patients with aniridia seem to be at increased risk. In spite of all available medical and surgical interventions, some eyes may still suffer this outcome.

Prevalence, Incidence, and Risk Factors for the Development of Glaucoma in Patients With Aniridia

PURPOSE

To assess the prevalence, incidence, and risk factors for the development of glaucoma in patients with aniridia.

METHODS

Retrospective analysis of case records of patients diagnosed as having congenital aniridia between January 1986 and December 2011 was performed. Patients with a follow-up of more than 12 months were included.

RESULTS

Ninety-one patients (180 eyes) with the diagnosis of aniridia were identified from the case records. Two eyes were excluded from the final analysis; one had developed phthisis and the other had been enucleated. Seventy-four patients (81.3%) were younger than 18 years at initial presentation. The prevalence of glaucoma at presentation was 28.8%, which could be further categorized as ocular hypertension in 19 eyes (10.5%) and glaucoma in 33 eyes (18.3%). Thirty-one eyes (28.4%) developed elevated intraocular pressure (IOP) during the follow-up period: ocular hypertension in 23 eyes (17.9%) and glaucoma in 8 eyes (6.25%). The mean IOP at the time of diagnosis was 33.9 ± 8.6 mm Hg (range: 24 to 60 mm Hg). The mean duration of follow-up was 8.1 ± 5.7 years (range: 1 to 28 years). The cumulative probability of developing elevated IOP was 4% at the end of 8 years of follow-up; this increased to 88% at the end of 28 years of follow-up. Univariate logistic regression analysis identified higher baseline IOP (odds ratio [OR]: 1.2; 95% confidence interval [CI]: 1.2 to 1.4) and limbal stem cell deficiency (OR: 2.8; 95% CI: 1.4 to 5.6) as significant risk factors for the development of elevated IOP. Higher baseline IOP remained significant on multivariate analysis (OR: 1.2; 95% CI: 1.2 to 1.4).

CONCLUSIONS

Glaucoma occurs in a substantial proportion of patients with aniridia. Eyes with increased IOP at baseline are at a higher risk. [J Pediatr Ophthalmol Strabismus. 2017;54(4):250-255.].

[Diagnostic capabilities of optical coherence tomography and confocal laser scanning microscopy in studying manifestations of aniridia-associated keratopathy]

AIM

to investigate the possible use of anterior segment optical coherence tomography (AS-OCT) and laser scanning confocal microscopy (LSCM) for visualization of limbal progenitor structures and epithelial changes at different stages of aniridia-associated keratopathy (AAK) and to analyze genotype-phenotype correlations of corneal damage.

MATERIAL AND METHODS

Thirty-four patients (63 eyes) with congenital aniridia (CA) were subjected to epithelial cell density measurement in the central cornea as well as epithelial surface assessment with limbal palisades of Vogt (POV) detection in the corresponding sites of the two corneas. For that, LSCM (HRT3) and AS-OCT (RTVue XR Avanti) were performed. Central corneal and epithelial thicknesses were measured using the Pachymetry protocol.

RESULTS

There has been found an increase in the central corneal thickness (CCT) of CA patients, which correlated with the stage of AAK, and a decrease in the central epithelial thickness as compared with healthy subjects (p<0.05). The difference between the basal and wing epithelial cells density in eyes with stages I and II AAK and normal cells density at stage 0 AAK was statistically significant (p<0.05). Intact or disturbed POV were detected in all patients with PAX6 3' deletion. At that, AS-OCT findings highly agreed with LSCM images for both the inferii (r_S=0.85, p<0.05) and superior limbi (r_S=0.53, p<0.05). A negative correlation was established between the stage of AAK and in vivo morphology of POV (r_S=-0.5, p<0.05). However, no correlation was found between the stage of AAK and patient's age (r_S=0.169, p=0.174).

CONCLUSION

AS-OCT and LSCM are both important diagnostic tools for corneal surface monitoring in patients with limbal stem cells deficiency.

Aniridia associated with ptosis in three generations of the same family

Aniridia is a spectrum of abnormalities of the iris anatomy, which range from a total absence of the iris to a mild stromal hypoplasia with normal pupil. Aniridia associated with ptosis in three generations of the same family is described. The cases fit the autosomal dominant familial aniridia (AN1) type, a genetic form of congenital aniridia characterised by isolated ocular defects.

Association of brain-derived neurotrophic factor (BDNF) haploinsufficiency with lower adaptive behaviour and reduced cognitive functioning in WAGR/11p13 deletion syndrome

In animal studies, brain-derived neurotrophic factor (BDNF) is an important regulator of central nervous system development and synaptic plasticity. WAGR (Wilms tumour, Aniridia, Genitourinary anomalies, and mental Retardation) syndrome is caused by 11p13 deletions of variable size near the BDNF locus and can serve as a model for studying human BDNF haploinsufficiency (+/-). We hypothesized that BDNF+/- would be associated with more severe cognitive impairment in subjects with WAGR syndrome. Twenty-eight subjects with WAGR syndrome (6-28 years), 12 subjects with isolated aniridia due to PAX6 mutations/microdeletions (7-54 years), and 20 healthy controls (4-32 years) received neurocognitive assessments. Deletion boundaries for the subjects in the WAGR group were determined by high-resolution oligonucleotide array comparative genomic hybridization. Within the WAGR group, BDNF+/- subjects (n = 15), compared with BDNF intact (+/+) subjects (n = 13), had lower adaptive behaviour (p = .02), reduced cognitive functioning (p = .04), higher levels of reported historical (p = .02) and current (p = .02) social impairment, and higher percentage meeting cut-off score for autism (p = .047) on Autism Diagnostic Interview-Revised. These differences remained nominally significant after adjusting for visual acuity. Using diagnostic measures and clinical judgement, 3 subjects (2 BDNF+/- and 1 BDNF+/+) in the WAGR group (10.7%) were classified with autism spectrum disorder. A comparison group of visually impaired subjects with isolated aniridia had cognitive functioning comparable to that of healthy controls. In summary, among subjects with WAGR syndrome, BDNF+/- subjects had a mean Vineland Adaptive Behaviour Compose score that was 14-points lower and a mean intelligence quotient (IQ) that was 20-points lower than BDNF+/+ subjects. Our findings support the hypothesis that BDNF plays an important role in human neurocognitive development.

[Aniridia, congenital glaucoma and white corneas in a newborn baby]

CASE REPORT

We present the case of a newborn baby in whom we observed aniridia, congenital glaucoma and edematous corneas, without clearance of the cornea after glaucoma surgery, and in whom a keratoplasty was considered. The patient had no evidence of systemic diseases and no deletion of chromosome 11.

DISCUSSION

It is important to perform a thorough ophthalmological and systemic exploration in newborn patients with aniridia due to other diseases that can be associated with it. We present the unusual case in which aniridia, congenital glaucoma and white corneas coexisted in a newborn baby. To our knowledge, such cases have only been reported twice before in the literature (Arch Soc Esp Oftalmol 2009; 84: 573-576).

Long-term visual prognosis of corneal and ocular surface surgery in patients with congenital aniridia

PURPOSE

To evaluate the long-term visual prognosis of corneal and ocular surface surgery in patients with congenital aniridia.

METHODS

Retrospective comparative interventional case series on 88 eyes of 45 patients with congenital aniridia treated and/or operated on from 1956 to present. Corneal and ocular surface findings were identified and patients were classified into operated (group I) or not operated (group II). Long-term best-ever best-corrected visual acuity (BCVA), final BCVA and long-term delta BCVA (long-term best-ever BCVA - final BCVA) were recorded and compared between the two groups, and between the limbal transplant (LT) (group I-A) and the penetrating keratoplasty (PK) (group I-B) patients. Postoperative results were also compared.

RESULTS

Limbal insufficiency was present in 58% of eyes and dense central corneal opacities were present in 27% of eyes. As a primary surgery, limbal allograft was performed in 10 eyes and PK in 13 eyes. The mean long-term follow-up times were 23 years in group I and 16 years in group II. The mean long-term delta BCVA was 0.032 in group I and 0.028 in group II. Comparisons of the VA means were insignificant (long-term best-ever, final BCVA and long-term delta BCVA). When comparing the LT and PK groups, mean long-term delta BCVA was 0.0328 in group I-A and 0.0382 in group I-B. Mean postoperative delta BCVA was 0.028 in group I-A and 0.048 in group I-B. We found no statistical significance between the LT and the PK groups as regards long-term postoperative BCVA results.

CONCLUSION

Long-term visual prognosis does not differ whether or not the patient undergoes surgery for aniridic keratopathy. LT and PK have comparable results over 5 years of follow-up because of the eventual failure of transplanted allografts.

Aniridia among children and teenagers in Sweden and Norway

PURPOSE

To investigate patients under the age of 20 with aniridia in Sweden and Norway in order to estimate the prevalence of aniridia, to describe clinical signs and identify complications in the young, which will help improve diagnostic tools and treatment.

METHODS

A thorough search for patients with aniridia (of all ages) was performed. Sixty-two of the 181 patients were under the age of 20. Fifty-two of them were examined and they constituted the study population. Patient history was obtained and all participants underwent clinical ophthalmologic examination, including photography. Blood samples were taken for mutation analysis.

RESULTS

Epidemiological data are only based on the results in Sweden. The age-specific prevalence in Sweden was 1:47,000, male/female ratio was 0.57, mean age 12 years and median age 14 years. The proportion of sporadic cases including WAGR (Wilms tumour, Aniridia, Genitourinary abnormalities, Mental Retardation) and Gillespie syndrome (aniridia, cerebellar ataxia and mental retardation) was 48%. In the entire study population (Sweden and Norway), the mean visual acuity (VA) was 0.2 (range 0.04-0.9). We found VA < 0.3 in 80% and <0.1 in 18% of the patients. Twenty-two patients (42%) had one or more of the sight threatening complications such as cataract/lens luxation, corneal clouding or glaucoma.

CONCLUSION

Descriptions of aniridia in the younger are rare. This study shows that aniridia seems to be more common than previously estimated and that some complications appear early in life. Watchfulness as regards these complications and regular examinations are essential even in the youngest.

Aniridia: current pathology and management

Aniridia is a rare panocular disorder affecting the cornea, anterior chamber, iris, lens, retina, macula and optic nerve. It occurs because of mutations in PAX6 on band p13 of chromosome 11. It is associated with a number of syndromes, including Wilm's tumour, bilateral sporadic aniridia, genitourinary abnormalities and mental retardation (WAGR) syndrome. PAX6 mutations result in alterations in corneal cytokeratin expression, cell adhesion and glycoconjugate expression. This, in addition to stem-cell deficiency, results in a fragile cornea and aniridia-associated keratopathy (AAK). It also results in abnormalities in the differentiation of the angle, resulting in glaucoma. Glaucoma may also develop as a result of progressive angle closure from synechiae. There is cataract development, and this is associated with a fragile lens capsule. The iris is deficient. The optic nerve and fovea are hypoplastic, and the retina may be prone to detachment. Aniridia is a profibrotic disorder, and as a result many interventions--including penetrating keratoplasty and filtration surgery--fail. The Boston keratoprosthesis may provide a more effective approach in the management of AAK. Guarded filtration surgery appears to be effective in glaucoma. Despite our increasing understanding of the genetics and pathology of this condition, effective treatment remains elusive.

Pax6 3' deletion results in aniridia, autism and mental retardation

The PAX6 gene is a transcription factor expressed early in development, predominantly in the eye, brain and gut. It is well known that mutations in PAX6 may result in aniridia, Peter's anomaly and kertatisis. Here, we present mutation analysis of a patient with aniridia, autism and mental retardation. We identified and characterized a 1.3 Mb deletion that disrupts PAX6 transcriptional activity and deletes additional genes expressed in the brain. Our findings provide continued evidence for the role of PAX6 in neural phenotypes associated with aniridia.

Cerebellar cognitive affective syndrome without global mental retardation in two relatives with Gillespie syndrome

Although previous studies of Gillespie syndrome have systematically reported a generalized delay of cognitive development (mental retardation or oligophrenia), psychometric data to substantiate this view are strikingly absent. In the present study two first degree relatives (mother and daughter) with Gillespie syndrome were neuropsychologically investigated. Aside from a marked asymmetry in the Wechsler-IQ profile, consisting of significantly better results on the verbal [Verbal IQ (VIQ)] than on the nonverbal part [Performance IQ (PIQ)] of the test, cognitive and behavioral assessments revealed a pattern of abnormalities that closely resembles the "cerebellar cognitive and affective syndrome" (CeCAS) (Schmahmann and Sherman, 1998). Aside from prefrontal dysexecutive dysfunctions such as disturbed cognitive planning and set-shifting, parietal lobe involvement was reflected by impaired visuo-spatial memory and visuo-spatial disorganization in constructional tasks. Within the linguistic domain involvement of the prefrontal and temporal language regions was indicated by impaired letter fluency, incidences of agrammatism, apraxia of speech and disrupted language dynamics. With regard to mood and behavior, a number of personality and affective characteristics were found that are typically associated with prefrontal lobe damage and dysfunction of limbic related regions in the cingulate and parahippocampal gyri. Disinhibited symptoms characterized behavior and affect of the mother while the daughter displayed a variety of inhibited symptoms. As a result, behavioral and cognitive findings in these patients do not support the prevailing view of a global mental retardation as a cardinal feature of Gillespie syndrome but primarily reflect cerebellar induced neurobehavioral dysfunctions following disruption of the cerebrocerebellar anatomical circuitry.

Acuity development in infantile nystagmus

PURPOSE

To compare development of acuity in patients with isolated infantile nystagmus and infantile nystagmus associated with a visual sensory defect.

METHODS

Visual acuities in 57 children (1 month to 4 years of age) with infantile nystagmus were assessed by using Teller acuity cards oriented vertically during binocular viewing. Twenty-two had isolated infantile nystagmus, 21 had albinism, 7 had aniridia, and 7 had mild or moderate bilateral optic nerve hypoplasia (BONH). Longitudinal acuity was measured in 40 of these patients (mean 1.8, 2.3, 3.1, and 3.3, measurements per patient group, respectively). The rate of acuity development across the study groups was quantified by linear regression of log acuity versus log age and compared to published normative data.

RESULTS

The rate of acuity development was similar across all groups and paralleled the normative data. The slope of log grating acuity versus log age (+/-SEM) was normal, 0.73; isolated infantile nystagmus, 0.80 +/- 0.11; albinism, 0.80 +/- 0.11; aniridia, 0.87 +/- 0.16; and BONH, 0.79 +/- 0.18. The slopes were not significantly different (ANCOVA, F(4,142) = 0.21, P = 0.93). Compared with published binocular normative data, mean acuity adjusted for age was reduced by 1.2 octaves in isolated infantile nystagmus and by 1.7 to 2.5 octaves in nystagmus with associated sensory defect.

CONCLUSIONS

The rate of acuity development in infantile nystagmus is largely independent of the gaze-holding instability or an associated visual sensory defect. Reduction of mean acuity in albinism, aniridia, and BONH is due to the visual sensory defect and exceeds the acuity reduction observed in isolated infantile nystagmus.

Auditory interhemispheric transfer deficits, hearing difficulties, and brain magnetic resonance imaging abnormalities in children with congenital aniridia due to PAX6 mutations

OBJECTIVE

To assess auditory processing, hearing difficulties, and brain magnetic resonance (MR) imaging abnormalities in children with panocular developmental aniridia due to PAX6 mutations.

DESIGN

Case-control study.

SETTING

Great Ormond Street Hospital and Institute of Child Health.

PARTICIPANTS

Eleven case subjects with PAX6 mutations and 11 age-matched and sex-matched healthy control subjects.

INTERVENTIONS

All subjects completed a structured hearing questionnaire, baseline audiometry, and central auditory tests (dichotic speech tests, frequency and duration pattern tests, and gaps-in-noise test). Case subjects underwent brain MR imaging with volumetry, and the results were compared with those of age-matched and sex-matched healthy control subjects randomly selected from the Radiology and Physics Unit database.

MAIN OUTCOME MEASURES

Brain MR imaging, central auditory test results, and questionnaire scores.

RESULTS

The corpus callosum area was significantly smaller on brain volumetry in the cases compared with the controls. The anterior commissure was small in 7 cases and was normal in 3 cases on visual inspection of brain MR images (conducted in 10 of 11 cases). Audiograms showed no abnormalities in any of the children. Central auditory test results were normal in all the controls and were abnormal in all the cases except for 1 case with a pattern of abnormalities consistent with reduced auditory interhemispheric transfer. The cases had greater difficulty localizing sound and understanding speech in noise than the controls.

CONCLUSIONS

Despite normal audiograms, children with PAX6 mutations may experience auditory interhemispheric transfer deficits and have difficulty localizing sound and understanding speech in noise. In view of their additional visual difficulties, thorough audiological evaluation of these children is indicated to initiate appropriate management.

Le glaucome dans l’aniridie

Aniridia consists in a congenital absence of the iris, with incidence varying from 1/64,000 to 1/96,000. This complex embryologic malformation involves the iris, trabecula, and cornea with limbal stem cell deficiency. Aniridia is a genetic haplo-insufficiency expression of the PAX6 gene located on chromosome 11p13. The associated clinical ocular signs could be congenital cataract, congenital glaucoma (the most common complication), keratopathy, ptosis, nystagmus, foveal aplasia, or microphthalmia. More than half of aniridic patients will develop glaucoma, so a regular complete tensional check-up is recommended. Central pachymetry is thicker than in the general population and overestimates ocular pressure if a corrective coefficient is not used. When glaucoma is diagnosed, medical or surgical treatment should be adapted to the child's age. In younger children, trabeculotomy is preferable to trabeculectomy in the first step if the cornea is clear enough. In older children or teenagers, a classical medical treatment must be initiated first, but surgical treatment will often be needed later. Trabeculectomy is the surgical procedure to choose for these older patients or can be combined with cataract surgery in adults. In severe glaucoma, after failure of trabeculectomy with or without mitomycin C, glaucoma surgery with drainage placement could be necessary to control ocular pressure and preserve vision. The outcome of glaucoma in aniridia is always severe and requires medical and surgical treatment adapted from infancy to adulthood.

[Glaucoma with aniridia and isolated congenital glaucoma in siblings: contribution and limits of genetics]

INTRODUCTION

Congenital glaucoma associated with aniridia and primary congenital glaucoma are regarded as different entities. Indeed, the abnormalities of the angle's structures as well as the genes involved are different. We report the observation of two sisters presenting these two types of glaucoma with particular attention paid to the importance and the difficulty of genetic counseling.

OBSERVATIONS

Child L, with no particular family history, had presented bilateral aniridia complicated by bilateral glaucoma since birth. In addition to medical and surgical treatment, general and genetic investigations were undertaken that revealed no abnormalities. No microdeletion of the gene PAX6 responsible for the aniridia was found. Consequently, the genetic advice was in favor of a second pregnancy for this couple. At birth, L's sister also presented bilateral congenital glaucoma, which was isolated, without aniridia. New genetic investigations were carried out but no abnormalities in PAX6, nor in FOXC1 or PITX2 involved in the development of the anterior chamber, were found. Moreover, the haplotypes for aniridia locus AN2 inherited by the two sisters were different, proof that this gene could not be responsible for the glaucoma.

DISCUSSION

At L's birth, the hypothesis retained was that she was a sporadic case whose gene mutation could not be identified (which happens in 50% of sporadic cases). The risk for the second pregnancy was negligible, although not null. The primary congenital glaucoma presented by L's sister remains unexplained in the context of aniridia and the role of the PAX6 gene was eliminated. The study of PITX2 and FOXC1 genes involved in anterior segment dysgenesis proved that they were also not involved. Thus, this observation evokes the responsibility of a gene other than PAX6 in aniridia, which could also have a role in isolated congenital glaucoma.

CONCLUSION

Analysis of congenital pathologies from a more genetic than clinical point of view seems to progressively break down the barriers established between the various phenotypes of hereditary congenital anomalies. Even if the association of aniridia and primary congenital glaucoma in siblings is reported here for the first time, it does not appear so extraordinary if one considers the complexity of the anterior chamber's development, which involves many genes, most of them still unidentified to date.

[Congenital aniridia keratopathy treatment]

OBJECTIVE

To attempt to review the aniridia keratopathy pathogenesis and establish a treatment protocol according to the severity of the symptoms.

METHODS

Personal experience in aniridic keratopathy management and a bibliography review.

RESULTS

The ocular manifestations of this anomaly include defects of the cornea, glaucoma, lens subluxation, cataracts, hypoplasia of the iris, fovea and optic nerve, amblyopia and nystagmus. The keratopathy occurs in a 20% of patients with aniridia. The correct PAX6 expression is necessary for normal corneal development, limbal stem cell activity and correct corneal epithelial cell migration and adhesion.

CONCLUSIONS

The management of ocular surface diseases due to limbal stem cell deficiency in aniridia is complex but has changed in recent years, as an understanding of the limbal stem cells and their microenvironment has modified the therapeutic approach. The use of autologous serum eye drops, amniotic membrane transplantation, limbal transplantation or cultivated limbal cell transplantation have all been reported as a treatment for several ocular surface diseases.

Novel mutations of the PAX6 gene identified in Chinese patients with aniridia

PURPOSE

Mutations in PAX6 are the major cause of aniridia. Only a few PAX6 mutations in Chinese have been reported. This study is to identify novel mutations in PAX6 of Chinese patients with aniridia.

METHODS

Aniridia patients were collected from 11 Chinese families, and genomic DNA was prepared from venous leukocytes. The coding regions of PAX6 were analyzed by direct sequencing of PCR products. Variations detected were further evaluated in available family members as well as in controls by using heteroduplex-SSCP analysis.

RESULTS

Four novel mutations including c.141+1G>A, c.184-3C>G, c.542C>A (Ser181X), and c.562C>T (Gln188X) and one known mutation c.120C>A (Cys40X) were identified in PAX6 of five unrelated patients with aniridia. All five mutations are expected to generate null alleles of PAX6. Varied ocular phenotypes were observed in different patients within families.

CONCLUSIONS

We identified four novel mutations and 1 known mutation in the human PAX6 gene. These results expand the mutation spectrum in PAX6 and enrich our knowledge of genotype-phenotype relation due to PAX6 mutations.

Bilateral Duane syndrome and bilateral aniridia

Duane retraction syndrome has been reported in association with structural abnormalities of the eye, including epibulbar dermoid, keratoconus, iris dysplasia, heterochromia iridis, persistent fetal vasculature, cataract, choroidal coloboma, microphthalmia, and optic nerve dysplasia. A novel association, that of bilateral Duane syndrome with bilateral aniridia, is the subject of this report.

Analysis by array CGH of genomic changes associated with the progression or relapse of Wilms' tumour

Despite aggressive salvage regimens, approximately half of all children who suffer a Wilms' tumour recurrence will die of their disease. Although there are increasing data on molecular genetic prognostic factors present in the tumour at diagnosis, there is little information regarding the molecular events that occur with Wilms' tumour progression and relapse. In the present study, microarray-based comparative genomic hybridization (aCGH) analysis has been carried out on 58 Wilms' tumour samples, which included 38 untreated primary and 20 recurrent tumours. A higher degree of copy number changes was observed in the recurrent tumours (33.0% genomic clones) than in the primary tumour (21.2%). Paired analysis highlighted the acquisition of 15q gain with high levels of IGF1R expression in the tumour recurrence in two cases. The most statistically significant abnormality acquired between diagnosis and relapse was loss of 17p. One case that experienced 17p loss was classified as favourable histology at diagnosis, but exhibited diffuse anaplasia at recurrence and had a homozygous TP53 deletion. Another instructive case with a constitutional 11p13 deletion presented with bilateral tumours and suffered two subsequent recurrences in the left kidney. A somatic WT1 mutation was found only in the right kidney tumour, while the constitutional 11p13 deletion was the only abnormality detected in the initial left kidney tumour by aCGH. The two subsequent relapses in the left kidney contained an accumulation of additional genetic alterations, including an independent WT1 mutation.

A progressive anterior fibrosis syndrome in patients with postsurgical congenital aniridia

PURPOSE

To report the characteristics of a newly recognized clinical entity in congenital aniridia that we have termed aniridic fibrosis syndrome.

DESIGN

Interventional case series.

METHODS

Retrospective chart review of 155 eyes in 80 patients with congenital aniridia was carried out to identify and characterize eyes that had anterior chamber fibrosis. Histopathologic evaluation was performed in three eyes.

RESULTS

Seven eyes in six patients were identified to have aniridic fibrosis syndrome. All eyes had undergone previous intraocular anterior segment surgery, some eyes with multiple procedures. Seven eyes had undergone cataract surgery with posterior chamber intraocular lens; six eyes had undergone previous implantation of tube shunt devices, and four eyes had undergone previous penetrating keratoplasty. Clinically, the syndrome was characterized by a progressive retrolenticular and retrocorneal membrane that caused forward displacement of intraocular lenses. Surgical findings indicated that the fibrotic membrane also can involve the ciliary body and anterior retina. Histopathologic evidence from three eyes indicated that the extensive fibrotic tissue originated from the root of the rudimentary iris and entrapped the intraocular lens haptics. Endothelial decompensation that was subsequent to the formation of the aniridic fibrosis syndrome was seen in all eyes.

CONCLUSION

Aniridic fibrosis syndrome is characterized by the development of a progressive anterior chamber fibrosis. A possible mechanism that promotes the formation of this fibrotic material may be the proximity or touching of intraocular devices on immature vessels in the rudimentary iris found in aniridia. Patients with aniridia with a history of penetrating keratoplasty, intraocular lenses, and tube shunts should be monitored for aniridic fibrosis syndrome; early surgical intervention is recommended.

[Clinical pathological study of the anterior lens capsule abnormalities in familial congenital aniridia with cataract]

OBJECTIVE

To observe the pathological changes of the lens and anterior lens capsule of the patients with familial congenital aniridia, and discuss the histopathological etiology of the fragility of the anterior capsule and the significance of surgical project.

METHODS

Anterior lens capsules and lens specimens were obtained from aniridic patients during cataract surgery. The intraoperative behavior of each capsule was noted, after which the specimens were submitted for histopathologic evaluation and electron microscope examination.

RESULTS

The anterior lens capsule was extremely fragile and remarkably thin. Degenerative changes(degeneration, necrosis, loss) of the lens epithelium and discontinuity of the lens epithelium were found in some specimens. Proliferation and double layer of the epithelial cells in some area of the specimens can be seen also. Ply structure of the anterior capsule became thin or disappeared.

CONCLUSION

Degenerative or proliferative changes of the lens epithelial cells were associated with the thinness and extreme intraperative fragility of the anterior lens capsules in familial aniridia with cataract. Greater awareness of anterior capsule fragility in some aniridic patients with cataract may reduce the risk of capsule complications and lead to safer surgical outcomes.

Developmental and cellular factors underlying corneal epithelial dysgenesis in the Pax6+/- mouse model of aniridia

Heterozygosity for a PAX6 deficiency (PAX6+/-) results in low levels of the PAX6 transcription factor and causes aniridia. Corneal changes in aniridia-related keratopathy (ARK) include peripheral pannus and epithelial abnormalities, which eventually result in corneal opacity and contribute to visual loss. The corneal abnormalities of Pax6+/- mice provide an excellent model for the corneal changes seen in PAX6+/- humans. The aim of the present study was to investigate the contributions of different factors (including altered cell proliferation, abnormal epithelial differentiation and incursion of the conjunctival epithelium) that may underlie the pathogenesis of the corneal changes caused by low levels of Pax6 in heterozygous Pax6+/Sey-Neu (Pax6+/-) mice. BrdU incorporation showed enhanced proliferation of Pax6+/- corneal epithelium compared to wild-type controls and analysis of p63 (a marker of high proliferative potential) revealed a slight increase in frequency of p63-positive basal corneal epithelial cells in Pax6+/- mice. Immunohistochemical investigation of K12 (a Pax6-regulated marker of corneal epithelial differentiation) in 2-52-week-old mice showed that K12 expression was delayed and down-regulated in the Pax6+/- corneal epithelium, implying that differentiation of the Pax6+/- corneal epithelium was delayed and abnormal. Goblet cells were identified within the peripheral corneal epithelium of the Pax6+/- eyes, but some were surrounded by cells expressing K12, suggesting they may have arisen in situ in the corneal epithelium. These findings suggest that low levels of Pax6 may be directly responsible for failure or delay of proper differentiation of the corneal epithelial cells, but the proliferative component of the mutant epithelium is probably not impaired. This abnormal differentiation suggests that ARK is not entirely attributable to a limbal stem cell deficiency.