Congenital iris ectropion as an indicator of variant aniridia

Argon laser trabeculoplasty for congenital ectropion uveae: Case report and review of the literature

A 18-year-old woman with unilateral glaucoma secondary to congenital ectropion uveae (CEU) in the right eye, without other systemic and ocular associations. Intraocular pressure (IOP) was uncontrolled under topical therapy. The visual field (VF) was within normal limits; retinal nerve fiber layer (RNFL) thickness, as evaluated by Optical Coherence Tomography (OCT), was reduced. The patient refused surgical intervention. After evaluation of the iridocorneal angle, ALT was performed as follows: 95 spots were applied for the 270 ° of visible trabecular meshwork using a laser beam diameter of 50 μm, an exposure time of 0.1 s and a power of 750 mw). Mean IOP in the right eye, as evaluated by diurnal tonometric curve, was 10 mmHg, 16 mmHg and 20 mmHg respectively one month, four months and eight months after ALT, with no additional topical therapy, and 18 mmHg twelve months after ALT with topical therapy. CEU is a rare, non-progressive anomaly characterized by the proliferation of iris pigment epithelium on anterior surface of iris; glaucoma, in this disorder, is often poorly controlled with medical therapy alone. In a phase of initial glaucomatous damage and with a not particularly high IOP, as in this case, ALT could be an alternative therapeutic option at least in the short-term, when surgery is not feasible immediately. In fact, given its limited effectiveness over time, ALT can be used as a temporary control measure of IOP, pending surgery to become feasible.

Neonatal-Onset Congenital Ectropion Uveae: A Distinct Phenotype of Newborn Glaucoma

PURPOSE

To describe neonatal-onset congenital ectropion uveae (N-CEU) as a distinct clinical entity of newborn glaucoma (NG) and to study its significance toward the severity and outcome of NG.

DESIGN

Prospective clinical cohort study.

METHODS

The study took place at a tertiary care postgraduate teaching institute. It included consecutive patients with NG who presented between July 1, 2016 and September 30, 2017, with a minimum postoperative follow-up of 1 year. Infants with any ocular anomaly apart from CEU were excluded. Patients with N-CEU were compared with those with neonatal-onset primary congenital glaucoma (N-PCG). All infants underwent goniotomy or trabeculotomy, with trabeculectomy depending on corneal clarity. Clinical features at presentation and outcome 1 year after surgery were defined as good or satisfactory if intraocular pressure was ≤16.0 mm Hg under anesthesia without or with topical medications, respectively, and poor if the infant required additional surgery.

RESULTS

Twenty eyes of 10 patients with N-CEU were compared with 16 eyes of 9 patients with N-PCG. Infants with N-CEU had significantly worse corneal clarity (mean grade 2.0 ± 0.7 vs 1.4 ± 0.8; P = .026) and poorer outcomes compared with those with N-PCG. Seven of 16 (43.7%) eyes with N-PCG had a cornea clear enough at presentation for a goniotomy compared with only 2 of the 20 (10%) eyes with N-CEU (P = .026). Thirteen of 16 (81.2%) eyes with N-PCG had a good or satisfactory outcome compared with 6 of 20 (30%) eyes with N-CEU (P = .001).

CONCLUSIONS

N-CEU appears to be distinct from the unilateral CEU in older patients described in the literature and may be considered a poorer prognosis phenotype of neonatal-onset glaucoma.

PAX6 aniridia syndrome: clinics, genetics, and therapeutics

PURPOSE OF REVIEW

Aniridia is a rare and panocular disorder affecting most of the ocular structures which may have significant impact on vision. The purpose of this review is to describe the clinical features, genetics, and therapeutic options for this disease and to provide an update of current knowledge and latest research findings.

RECENT FINDINGS

Aside from the ocular features, a variety of associated systemic abnormalities, including hormonal, metabolic, gastrointestinal, genitourinary, and neurologic pathologies have been reported in children with aniridia. Although mutations in PAX6 are a major cause of aniridia, genetic defects in nearby genes, such as TRIM44 or ELP4, have also been reported to cause aniridia. Recent improvement in genetic testing technique will help more rapid and precise diagnosis for aniridia. A promising therapeutic approach called nonsense suppression therapy has been introduced and successfully used in an animal model.

SUMMARY

Aniridia is a challenging disease. The progressive nature of this condition and its potential complications require continuous and life-long ophthalmologic care. Genetic diagnosis for aniridia is important for establishing definitive molecular characterization as well as identifying individuals at high risk for Wilms tumor. Recent advancement in understanding the genetic pathogenesis of this disease offers promise for the approaches to treatment.

Newly identified paired box 6 mutation of variant familial aniridia: Congenital iris ectropion with foveal hypoplasia

Congenital aniridia is a kind of eye disease characterized by complete or partial hypoplasia of the iris and is associated with other ocular anomalies including corneal opacity, glaucoma, and foveal hypoplasia. Heterozygous mutation of paired box 6 (PAX6) gene was identified in most cases of aniridia, with iatrogenic mutations accounting for about two-third of the cases and chromosomal rearrangements accounting for the other one-third. We report rare cases of variant aniridia, congenital iris ectropion associated with foveal hypoplasia in both a woman and her son with a mutation of PAX6 gene. To our knowledge, deletion c. 936delC in exon 8 of PAX6 gene has not been reported until now.

A young Botswana patient with congenital iris ectropion uvea

Congenital iris ectropion is a rare condition; non-progressive anomaly characterised by the presence of iris pigment epithelium on the anterior surface of the iris stroma and is frequently associated with anterior iris insertion, dysgenesis of the drainage angle and glaucoma. This paper describes unusual case of bilateral case of congenital iris ectropion in adult patient with pupillary abnormality, normal anterior chamber angle structure and with no evidence of glaucoma.

Sporadic and Familial Congenital Cataracts: Mutational Spectrum and New Diagnoses Using Next-Generation Sequencing

Congenital cataracts are a significant cause of lifelong visual loss. They may be isolated or associated with microcornea, microphthalmia, anterior segment dysgenesis (ASD) and glaucoma, and there can be syndromic associations. Genetic diagnosis is challenging due to marked genetic heterogeneity. In this study, next-generation sequencing (NGS) of 32 cataract-associated genes was undertaken in 46 apparently nonsyndromic congenital cataract probands, around half sporadic and half familial cases. We identified pathogenic variants in 70% of cases, and over 68% of these were novel. In almost two-thirds (20/33) of these cases, this resulted in new information about the diagnosis and/or inheritance pattern. This included identification of: new syndromic diagnoses due to NHS or BCOR mutations; complex ocular phenotypes due to PAX6 mutations; de novo autosomal-dominant or X-linked mutations in sporadic cases; and mutations in two separate cataract genes in one family. Variants were found in the crystallin and gap junction genes, including the first report of severe microphthalmia and sclerocornea associated with a novel GJA8 mutation. Mutations were also found in rarely reported genes including MAF, VIM, MIP, and BFSP1. Targeted NGS in presumed nonsyndromic congenital cataract patients provided significant diagnostic information in both familial and sporadic cases.

Congenital iris ectropion uveae presenting with glaucoma in infancy

A healthy 5-month-old boy presented with a sporadic unilateral right-sided sectorial ectropion uveae, anterior insertion of the iris root, increased IOP, and glaucomatous disk changes. The absence of other additional ocular anomalies and the appearance of the angle led to a diagnosis of congenital iris ectropion syndrome. IOPs became refractory to maximal topical therapy, and trabeculotomy surgery was performed. The patient has since been stabilized on topical agents.

Glaucoma and Frequency of Ocular and General Diseases in 30 Patients with Aniridia: A Clinical Study

Purpose

To evaluate the following in patients with aniridia: age at first examination at the University Eye Hospital and age at diagnosis of glaucoma; visual acuity; frequency of family history of aniridia; and frequency of ocular and general diseases associated with aniridia.

Methods

This was a consecutive examination of 30 unrelated patients with aniridia and retrospective evaluation of ophthalmologic, pediatric, and internal findings. The relative frequency of age at glaucoma diagnosis within decades was evaluated for the 20 patients with aniridia and glaucoma. Statistical analysis was performed using the Mann-Whitney test.

Results

Relative frequency of the age of patients with aniridia at time of glaucoma diagnosis within the following decades was as follows: from birth to 9 years: 15%, 10-19: 15%, 20-29: 15%, 30-39: 15%, 40-49: 35%, and 50-59: 5%. Visual acuity in the better eye of 20/100 or less was found in 60%. Family history of aniridia was found in 33.3% of patients, with 1-4 relatives with aniridia. A total of 76.7% of patients had congenital cataract, and 66.7% had glaucoma. Mean maximum intraocular pressure of the 20 patients with glaucoma was 35.9 mmHg in the right and 32.6 mmHg in the left eye. A total of 53.3% had nystagmus, 26.6% corneal opacifications, 16.7% bilateral lens dislocation upwards, 6.7% optic nerve hypoplasia, 3.3% poor foveal development, and 3.3% Wilms tumor.

Conclusions

Up to the age of 40 years, 15% of patients were diagnosed with glaucoma per age decade. Frequent bilateral glaucoma and similar bilateral height of intraocular pressure suggest a genetic glaucoma disposition with malformation at Schlemm canal, besides possible sequential anatomic changes in the chamber angle. Associated ocular abnormalities limit visual prognosis.

Molecular characterization of newborn glaucoma including a distinct aniridic phenotype

PURPOSE

To characterize the underlying genetic defect in otherwise healthy Saudi newborns with buphthalmos, including those with iris abnormalities.

METHODS

Prospective case series of affected Saudi Arabian probands who were referred for genetic counseling over a 4 year period. All had CYP1B1 sequencing. Selected patients with visible iris abnormalities had PAX6, FOXC1, and PITX2 sequencing. CYP1B1-negative patients had LTBP2 sequencing.

RESULTS

All 67 probands had corneal enlargement with variable haze/scarring evident to caregivers at birth; 46 had a family history of infantile or early childhood glaucoma. All families were consanguineous except for 6, 2 of which were endogamous. Eight probands had mild ectropion uveae with partial aniridia; 2 probands had thick scarred corneas that precluded careful iris examination. Homozygous or compound heterozygous CYP1B1 mutations were identified in 91% (61/67), including all 8 probands with ectopion uveae and partial aniridia. The common Saudi mutation p.G61E occurred in most cases (38 homozygous, 8 compound heterozygous). Four novel mutations were identified (p.N252K, p.V460E, p.S485F, p.N519D). No mutations were identified in the other screened genes.

CONCLUSIONS

Newborn glaucoma on the Arabian Peninsula is typically CYP1B1-related even in the setting of developmental iris abnormality. Mild iris ectropion with partial aniridia in a newborn with glaucoma suggests mutations in CYP1B1 rather than in other genes associated with anterior segment dysgenesis. On the Arabian Peninsula p.G61E mutations are the major cause of newborn glaucoma but novel CYP1B1 mutations continue to be documented. The fact that the 9% of cases that were CYP1B1-negative did not have mutations in LTBP2 suggests that there exists at least 1 additional locus for this condition.

PAX6Mutations May Be Associated with High Myopia

PAX6 is a key regulator of eye development and there are many well recognized ophthalmic sequelae of mutations at this locus. The 14 exon PAX6 gene is well conserved across species and phyla. Coding region mutations manifest in a variety of phenotypes. Predicted premature protein truncations are generally associated with classical aniridia. Missense mutations are often found in cases with variant phenotypes such as ectopia pupillae; isolated foveal hypoplasia; nystagmus and hyaloid vessel proliferation. The locus has also been implicated, through a genome-wide sib-pair scan, to be important in the normal variation of myopia. We investigated the association between identified PAX6 mutations and refractive error in Australian patients from four pedigrees. Two of eight subjects with a 1410delC PAX6 mutation had a mean spherical equivalence < -9D, whilst a mean spherical equivalence < or = -5D was recorded in two from four subjects with an Arg240Stop PAX6 mutation and one of two subjects with a Glu93Stop mutation. One individual identified with a Pro346Ala PAX6 mutation had a mean spherical equivalence of +2.8 D. Thus, our observations generally support other incidental findings, that PAX6 mutation, particularly predicted haploinsufficiency, may be associated with extreme refractive error, although the mechanism by which this occurs is not clear.

Chromosomal rearrangements and novel genes in disorders of eye development, cataract and glaucoma

Disorders of eye development such as microphthalmia and anophthalmia (small and absent eyes respectively), anterior segment dysgenesis where there may be pupillary and iris anomalies, and associated cataract and glaucoma, often lead to visual impairment or blindness. Currently treatment options are limited, as much is unknown about the molecular pathways that control normal eye development and induce the aberrant processes that lead to ocular defects. Mutation detection rates in most of the known genes are generally low, emphasizing the genetic heterogeneity of developmental ocular defects. Identification of the disease genes in these conditions improves the clinical information available for affected individuals and families, and provides new insights into the underlying biological processes for facilitation of better treatment options. Investigation of chromosomal rearrangements associated with an ocular phenotype has been especially powerful for disease gene identification. Molecular characterization of such rearrangements, which pinpoints the region by physically disrupting the causative gene or its regulatory sequences, allows for rapid elucidation of underlying genetic factors that contribute to the phenotype. Genes including PAX6, PITX2, FOXC1, MAF, TMEM114, SOX2, OTX2 and BMP4 have been identified in this way to be associated with developmental eye disorders. More recently, new methods in chromosomal analysis such as comparative genomic hybridization (CGH) microarray, have also enhanced our ability in disease gene identification.