Aniridia

We reported previously the characterization of Pax-QNR/Pax-6 products expressed in the avian neuroretina. Five proteins (48, 46, 43, 33, and 32 kDa) were characterized, among which the 33 and 32 kDa proteins are devoid of the paired domain. In contrast to the 48-kDa (containing an alternative paired exon 4a) and 46-kDa proteins exclusively located in the nucleus, the 43- (in which the paired exon 5 is spliced out), 33-, and 32-kDa proteins were also found in the cytoplasmic compartment. We report the identification of two nuclear targeting sequences: the basic LKRKLQR region (amino acids 206-212) located in the NH2 terminus of the homeodomain used by the p43 and 33/32 kDa proteins; and the paired exon 5 sequence. A case of human aniridia, where arginine 208 of LKRKLQR is mutated into a tryptophan, has been reported recently. We introduced this mutation into the Pax-QNR p46, p43, and p33/32 proteins. No effect on the nuclear localization or in transactivation potential of the protein...

Aniridia is a panocular disorder which occurs in 1/50,000 to 1/100,000 live births and can appear either in isolated form or in the context of a syndrome. Isolated aniridia is inherited as an autosomal dominant condition and is caused by mutations of the PAX6 gene. A variety of techniques and methodologies within molecular genetics and cytogenetics are used to study these mutations. To identify the different aspects of this disease and to provide a guide for proper genetic diagnosis leading to improved clinical management of the disease. Aniridia is an autosomal dominant disease that primarily affects the iris, though it can impact most of the ocular structures. The disease is mainly caused by mutations in the PAX6 gene located on chromosome 11p13 which encodes a transcription factor that is involved in the development of the eye. Genetic analysis of aniridia is complex and requires the use of both molecular genetics and cytogenetics techniques. These procedures are indicated in all cases of aniridia. It is important bear certain clinical and technical aspects in mind prior to starting analysis or providing genetic counseling for patients and their families. The use of molecular genetic techniques in the genetic diagnosis of aniridia enables patients and their families to receive better clinical management.

Gillespie syndrome (GS) is characterized by bilateral iris hypoplasia, congenital hypotonia, non-progressive ataxia, and progressive cerebellar atrophy. Trio-based exome sequencing identified de novo mutations in ITPR1 in three unrelated individuals with GS recruited to the Deciphering Developmental Disorders study. Whole-exome or targeted sequence analysis identified plausible disease-causing ITPR1 mutations in 10/10 additional GS-affected individuals. These ultra-rare protein-altering variants affected only three residues in ITPR1: Glu2094 missense (one de novo, one co-segregating), Gly2539 missense (five de novo, one inheritance uncertain), and Lys2596 in-frame deletion (four de novo). No clinical or radiological differences were evident between individuals with different mutations. ITPR1 encodes an inositol 1,4,5-triphosphate-responsive calcium channel. The homo-tetrameric structure has been solved by cryoelectron microscopy. Using estimations of the degree of structural change ...

To evaluate childhood filtration surgery when using releasable sutures, antimetabolites, and bleb-needling with 5-fluorouracil (5FU).Retrospective case note review of 30 patients (38 eyes) with childhood glaucoma presenting between 1999 and 2004 to a tertiary pediatric ophthalmology center. Either trabeculectomy or combined trabeculotomy-trabeculectomy using antimetabolites, releasable sutures, and bleb modification was performed. Successful outcomes for survival analysis were measured intraocular pressures ≤21 mmHg, with two or less topical medications.Patients under 1 year old had trabeculotomy-trabeculectomy; the remainder had trabeculectomy alone. One case of primary congenital glaucoma had trabeculotomy-trabeculectomy at 24 months. Eighty-nine percent had previous failed glaucoma surgery. Twenty-five patients (33 eyes) had primary congenital glaucoma; 5 patients (5 eyes) had secondary glaucoma (aphakia or pseudophakia). Mean follow-up was 22.9 months (5.2-68.5). Sixty-six percent of all eyes had suture-release and 68% had bleb-needling (mean, 1.9 times). Five eyes (13%) needed further drainage tube surgery. Complications were early postoperative hypotony in three cases, requiring anterior chamber reinflation (mean age, 7.4 months at the time of surgery), two cases of transient wound leak, but no bleb-related complications or endophthalmitis. No blebs were avascular, or thin and cystic. Cumulative success was 75% for primary, but only 21% for secondary glaucoma at final follow-up.Antimetabolite and releasable augmentation of filtration surgery appear to give favorable outcomes in the treatment of refractory primary pediatric glaucomas. Secondary glaucomas after cataract surgery do not show good long-term success. There were no major or sight-threatening complications in our series; no eyes developed cystic avascular blebs or bleb-related infections.

To evaluate the safety and efficacy of Morcher 96F iris diaphragm implantation to manage small defects of the human iris. Jules Stein Eye Institute, UCLA, Los Angeles, California, USA. Prospective nonrandomized interventional case series. Demographic, preoperative, and postoperative data of patients who had implantation of the modified capsular tension ring (CTR) and followed to 1 year were reviewed. Safety measures included loss of corrected distance visual acuity (CDVA), perioperative complications, adverse events, and secondary surgical interventions. Efficacy measures included CDVA with glare, daytime and nighttime glare symptom scores, and subjective cosmesis scores. Sixteen patients had CTR implantation. There was a statistically significant improvement in the median CDVA of 2.5 Snellen lines (P < .01), with 4 patients having minor decreases in CDVA for reasons unrelated to the device. There were no intraoperative complications. Three adverse events were reported: 1 ocular ...

The PAX6 gene was first described as a candidate for human aniridia. However, PAX6 expression is not restricted to the eye and it appears to be crucial for brain development. We studied PAX6 mutations in a large spectrum of patients who presented with aniridia phenotypes, Peters' anomaly, and anterior segment malformations associated or not with neurological anomalies. Patients and related families were ophthalmologically phenotyped, and in some cases neurologically and endocrinologically examined. We screened the PAX6 gene by direct sequencing in three groups of patients: those affected by aniridia; those with diverse ocular manifestations; and those with Peters' anomaly. Two mutations were investigated by generating crystallographic representations of the amino acid changes. Three novel heterozygous mutations affecting three unrelated families were identified: the g.572T>C nucleotide change, located in exon 5, and corresponding to the Leucine 46 Proline amino-acid mutat...

Paired box gene 6 (PAX6) heterozygous mutations are well known to cause congenital non-syndromic aniridia. These mutations produce primarily protein truncations and have been identified in approximately 40%-80% of all aniridia cases worldwide. In Mexico, there is only one previous report describing three intragenic deletions in five cases. In this study, we further analyze PAX6 variants in a group of Mexican aniridia patients and describe associated ocular findings. We evaluated 30 nonrelated probands from two referral hospitals. Mutations were detected by single-strand conformation polymorphism (SSCP) and direct sequencing, and novel missense mutations and intronic changes were analyzed by in silico analysis. One intronic variation (IVS2+9G>A), which in silico analysis suggested had no pathological effects, was searched in 103 unaffected controls. Almost all cases exhibited phenotypes that were at the severe end of the aniridia spectrum with associated ocular alterations such as...

We report molecular genetic analysis of 42 affected individuals referred with a diagnosis of aniridia who previously screened as negative for intragenic PAX6 mutations. Of these 42, the diagnoses were 31 individuals with aniridia and 11 individuals referred with a diagnosis of Gillespie syndrome (iris hypoplasia, ataxia and mild to moderate developmental delay). Array-based comparative genomic hybridization identified six whole gene deletions: four encompassing PAX6 and two encompassing FOXC1. Six deletions with plausible cis-regulatory effects were identified: five that were 3' (telomeric) to PAX6 and one within a gene desert 5' (telomeric) to PITX2. Sequence analysis of the FOXC1 and PITX2 coding regions identified two plausibly pathogenic de novo FOXC1 missense mutations (p.Pro79Thr and p.Leu101Pro). No intragenic mutations were detected in PITX2. FISH mapping in an individual with Gillespie-like syndrome with an apparently balanced X;11 reciprocal translocation revealed ...

An incidence of bilateral gonadoblastoma in a 23-month old, mentally retarded boy with congenital sporadic aniridia, undescended dysgenetic testes, deletion of a chromosome (11) (p1302p14.2) and a later occurring unilateral Wilms' tumor is reported. The patient was treated by bilateral gonadectomy, nephrectomy, and chemotherapy, and is alive and well five years later. Another three aniridia/gonablastoma observations from the literature are discussed, two of them without and one in combination with Wilms' tumor. Diagnosis of gonadoblastoma remained unsuspected in two cases until autopsy and in another two cases it was done at surgery. A comparison of four cases reveals common finding--aniridia, dysgenetic gonads, genital abnormalities, mental retardation, deletion of 11p13, early occurrence and bilaterality of gonadoblastoma.

Purpose. Efficacy of cultivated oral mucosa epithelial transplantation (COMET) procedure in corneal epithelium restoration of aniridia patients.Methods. Study subjects were aniridia patients (13 patients; 17 eyes) with irregular, vascular conjunctival pannus involving visual axis who underwent autologous transplantation of cultivated epithelium. For the procedure oral mucosa epithelial cells were obtained from buccal mucosa with further enzymatic treatment. Suspension of single cells was seeded on previously prepared denuded amniotic membrane. Cultures were carried on culture dishes inserts in the presence of the inactivated with Mitomycin C monolayer of 3T3 fibroblasts. Cultures were carried for seven days. Stratified oral mucosa epithelium with its amniotic membrane carrier was transplanted on the surgically denuded corneal surface of aniridia patients with total or subtotal limbal stem cell deficiency.Outcome Measures. Corneal surface, epithelial regularity, and visual acuity imp...

Aniridia is a rare developmental disorder. Glaucoma and complications associated with glaucoma surgery are a major cause of blindness in patients with aniridia. We describe here a case of a nine year old boy who presented with familial aniridia of both eyes along with glaucoma. He was treated by trabeculectomy of both eyes, which was successful in controlling the glaucoma.

The PAX6 gene belongs to the Paired box (PAX) family of transcription factors that is tissue specific and required for the differentiation and proliferation of cells in embryonic development. PAX6 regulates the pattern formation in early developmental stages. This function of PAX6 protein enables the successful completion of neurogenesis and oculogenesis in most animals such as mice, Drosophila and some other model organisms including humans. A variation in the sequence of PAX6 gene may alter the function and structure of the protein. Such changes can produce adverse effects on functioning of the PAX6 protein which were clinically observed to occur in a broad range of ocular defects such as aniridia in humans. We employed in silico prediction methods such as SIFT, PolyPhen 2; I mutant 3.0, SNAP, SNPs&GO, and PHD-SNP to screen the pathogenic missense mutation in PAX6 and DNA binding sites by BindN and BindN +. Furthermore, we employed KD4V server to examine the structural and functional modifications that occur in the PAX6 protein as a result of mutation. Based on the results obtained from the in silico prediction methods, we carried out modeling analysis for V53L, I56T, G64V, and I87R to visualize the impact of mutation in structural context.

The PAX6 gene was first described as a candidate for human aniridia. However, PAX6 expression is not restricted to the eye and it appears to be crucial for brain development. We studied PAX6 mutations in a large spectrum of patients who presented with aniridia phenotypes, Peters' anomaly, and anterior segment malformations associated or not with neurological anomalies. Patients and related families were ophthalmologically phenotyped, and in some cases neurologically and endocrinologically examined. We screened the PAX6 gene by direct sequencing in three groups of patients: those affected by aniridia; those with diverse ocular manifestations; and those with Peters' anomaly. Two mutations were investigated by generating crystallographic representations of the amino acid changes. Three novel heterozygous mutations affecting three unrelated families were identified: the g.572T>C nucleotide change, located in exon 5, and corresponding to the Leucine 46 Proline amino-acid mutat...

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

To study the association between congenital aniridia and dry eyes, and the status of limbal stem cells. Single-center, retrospective, noninterventional, comparative case series. Twenty patients (36 eyes) diagnosed with congenital aniridia. Retrospective review of medical records at the King Khaled Eye Specialist Hospital in Riyadh, Saudi Arabia to identify all cases of congenital aniridia. Selected patients were requested to undergo further testing, especially for evaluation of dry eyes. Full ocular examinations were performed, including examination of the meibomian gland orifices and dry eye evaluation (by predetermined criteria of tear breakup time, tear meniscus level, presence of mucoid secretions, Schirmer's test with and without anesthesia, and fluorescein and rose Bengal staining patterns of the cornea and conjunctiva). Cytological evaluation was performed in 23 aniridic eyes by impression cytology to determine limbal stem cell status relative to control normal eyes. Abnormal tear film production and stability, meibomian gland dysfunction, severity of corneal involvement, and limbal stem cell deficiency. Twenty patients (36 eyes) diagnosed with congenital aniridia were classified into 3 groups according to the severity of corneal involvement: mild (2 eyes), moderate (21 eyes), and advanced (13 eyes) corneal changes. Tear breakup time was reduced by an average of 5 seconds in 90.7% of cases, tear meniscus levels were reduced to <0.5 mm in 88.6% of cases, and stenosed meibomian orifices were found in 77.8% of patients. Dry eyes (94%) correlated with the severity of corneal involvement (P = 0.001). Impression cytology revealed metaplasia in all tested cases. Furthermore, 8 of 23 eyes (35%) and 15 of 23 eyes (65%) had early and advanced limbal stem cell deficiency, respectively. Abnormal tear film stability and meibomian gland dysfunction are newly identified factors in patients with aniridia. Both correlate to the severity of ocular surface disease. Impression cytology is informative in diagnosing various degrees of limbal stem cell deficiency, which is present in all tested aniridia eyes.