Geographical variation in anophthalmia and microphthalmia in England, 1988-94

Congenital Malformations of the Eye: A Pictorial Review and Clinico-Radiological Correlations

Congenital malformations of the eye represent a wide and heterogeneous spectrum of abnormalities that may be part of a complex syndrome or be isolated. Ocular malformation severity depends on the timing of the causative event during eye formation, ranging from the complete absence of the eye if injury occurs during the first weeks of gestation, to subtle abnormalities if the cause occurs later on. Knowledge of ocular malformations is crucial to performing a tailored imaging protocol and correctly reporting imaging findings. Together with the ophthalmologic evaluation, imaging may help frame ocular malformations and identify underlying genetic conditions. The purpose of this pictorial review is to describe the imaging features of the main ocular malformations and the related ophthalmologic findings in order to provide a clinico-radiological overview of these abnormalities to the clinical radiologist. Sight is a crucial sense for children to explore the world and relate with their parents from birth. Vision impairment or even blindness secondary to ocular malformations deeply affects children's growth and quality of life.

Ocular Manifestations in Patients with Fanconi Anemia: A Single-Center Experience Including 106 Patients

OBJECTIVES

To describe the prevalence of acquired ocular manifestations in patients with Fanconi anemia (FA) and to describe and correlate the congenital ocular malformations with the genetic subtypes of the disease.

STUDY DESIGN

This is a cross-sectional observational study of 106 consecutive patients with confirmed diagnosis of FA who were followed at the Hematopoietic Stem Cell Transplantation (HSCT) Service at the Federal University of Paraná, Curitiba, Parana, Brazil. Participants underwent a complete ophthalmologic evaluation and 84 patients underwent ocular ultrasound examination. This study was conducted between November 2014 and August 2017.

RESULTS

The patients ranged in age from 6 months to 43 years of age. Microphthalmia was the most common congenital ocular abnormality (95.2%). A decrease in anthropometric measurements was observed, including palpebral fissure length (78/103 patients [76.5%]), microcornea (48/103 patients [46.6%]), and ptosis (31/103 patients [30.1%]). We identified a new ophthalmic condition in 15 patients with FA, that is, epiretinal tissue on the optic disc. The genetic subtype was identified in 78 patients (79.6%), the FA-A subtype was most prevalent (50%). The most common acquired ocular manifestation (non-graft-versus-host disease [GVHD] related) in patients who did not undergo HSCT (n = 44) was limbal neovascularization (13.6%), whereas in patients who underwent HSCT (n = 62), the GVHD-related manifestation was ocular GVHD (51.6%). The most frequent symptom of ocular GVHD was keratoconjunctivitis sicca (29%).

CONCLUSIONS

Several ocular manifestations were identified in patients with FA.

Anophthalmia and microphthalmia in children: associated ocular, somatic and genetic morbidities and quality of life

PURPOSE

To report ocular outcome, somatic co-morbidities, genetics, and quality of life in children born with anophthalmia (A) or microphthalmia (M).

METHODS

Thirty-five children (19 boys) with A/M underwent ophthalmological examinations and a review of medical records. Parents of 12/22 cases completed the Pediatric Quality of Life Inventory (PedsQL).

RESULTS

Age at examination ranged from 7 months to 18 years (median 2.3 years). Ten cases were totally blind or had light perception. Isolated A/M occurred in 16/35 cases, while somatic, psychomotor, neuroradiological and/or genetic pathology occurred in 19/35 cases both in the bilateral (7/9) and in the unilateral group (12/26). Among 26 unilateral cases, 4/16 with one normal eye had associated problems compared to 9/10 if the contralateral eye was pathological (p < .01). There was an increased risk for heart defects in children with psychomotor delay (p = .04). Pathogenic genetic abnormalities were identified in 10/24 cases. Neuroimaging demonstrated pathology in 14/20 cases with corpus callosum dysgenesis (6/20) being the most common. The median total PedsQL score of parent reports for ages 2-12 was 52.4 (range 22.6-100).

CONCLUSIONS

Somatic, psychomotor and/or neuroradiological pathologies were more common in bila-teral than unilateral cases, but the difference was not significant. There was decreased risk in unilateral cases with one normal eye. Genetic defects occurred in both unilateral and bilateral cases. Health-related quality of life was reduced.

Bilateral severe microphthalmos with bilateral colobomatus orbitopalpebral cyst: accessibility of speciality eye-care and rehabilitation services in low and middle-income countries

A 12-year-old girl presented with an unusually large mass under the right lower eyelid and a smaller mass under the left lower lid since the last 6 months. The parents had noticed the absence of the right eyeball and a very small left eyeball and no vision in both eyes since birth but did not approach the healthcare system. The patient was diagnosed as a case of bilateral severe microphthalmos with colobomatous cyst with late presentation and was treated surgically. The parents were counselled for education and training of the child in schools for visually impaired. Early treatment and rehabilitation help patients lead a normal life in these cases. In rural areas, patients face challenges in getting access to the specialty eye-care services due to several barriers, including lack of availability and affordability. This case highlights the disparities in essential health services in low and middle-income countries.

Children and young adults with anophthalmia and microphthalmia: Diagnosis and Management

PURPOSE

Congenital anophthalmia (A) and microphthalmia (M) are rare developmental defects, which could be isolated or syndromic. Our objective was to describe a cohort of children and young adults with A/M treated with ocular prosthesis, emphasizing clinical features, diagnosis, treatment, and follow-up.

METHODS

Eighteen individuals (10 female) with unilateral A (n = 3) and M (n = 15) with a mean age of 9.5 years (range 0.8-31.8) and treated with ocular prosthesis were included. Data on medical history, clinical examinations and management of ocular prosthesis were collected. Genetic screening with microarray and whole-exome sequencing targeting 121 A/M-related genes was performed.

RESULTS

A/M appeared isolated (seven cases) or as part of a syndromic condition (11 cases). In 4/16 patients, mutations were detected in TFAP2A, CHD7, FOXE3 and BCOR-genes. In one patient, a possibly causal microdeletion 10q11 was shown. Associated ocular anomalies such as cataract and cysts were found in 16 (89%) of the A/M eyes, and in nine (50%) ophthalmological findings were found in the fellow eyes. The median ages at which the conformer and ocular prosthesis first were initiated were 7.8 months and 1.5 years. 16/17 patients fulfilled satisfactory orbital growth and cosmetic results when treated with ocular prosthesis from an early age.

CONCLUSION

Based upon our findings, a multidisciplinary approach, including genetic assessment, is necessary to cover all aspects of A/M. Imaging, ultrasound and visual evoked potentials should be included. Early management is crucial for the outcome, in terms of non-ocular findings, vision in the fellow eye, and for facial cosmetic development.

Structural and functional brain reorganisation due to blindness: The special case of bilateral congenital anophthalmia

Investigating the changes in the brain that result from a loss of sensory input has provided significant insight into the considerable capacity of the brain to reorganise. One of the difficulties in studying sensory-deprived populations is that the time and extent of sensory loss vary significantly. In this review, we consider the changes in the human brain associated with complete absence of visual input resulting from bilateral congenital anophthalmia, in which the eyes fail to develop. We describe the functional reorganisation and associated structural and connectivity changes that occur in the brain of those affected by the condition. By considering animal models of this condition, we investigate the changes that may be occurring on a scale that is not captured by human in vivo imaging techniques. Finally, we lay out a model pathway for taking auditory information to the occipital cortex that may be specific to anophthalmia.

Genetics of anophthalmia and microphthalmia. Part 1: Non-syndromic anophthalmia/microphthalmia

Eye formation is the result of coordinated induction and differentiation processes during embryogenesis. Disruption of any one of these events has the potential to cause ocular growth and structural defects, such as anophthalmia and microphthalmia (A/M). A/M can be isolated or occur with systemic anomalies, when they may form part of a recognizable syndrome. Their etiology includes genetic and environmental factors; several hundred genes involved in ocular development have been identified in humans or animal models. In humans, around 30 genes have been repeatedly implicated in A/M families, although many other genes have been described in single cases or families, and some genetic syndromes include eye anomalies occasionally as part of a wider phenotype. As a result of this broad genetic heterogeneity, with one or two notable exceptions, each gene explains only a small percentage of cases. Given the overlapping phenotypes, these genes can be most efficiently tested on panels or by whole exome/genome sequencing for the purposes of molecular diagnosis. However, despite whole exome/genome testing more than half of patients currently remain without a molecular diagnosis. The proportion of undiagnosed cases is even higher in those individuals with unilateral or milder phenotypes. Furthermore, even when a strong gene candidate is available for a patient, issues of incomplete penetrance and germinal mosaicism make diagnosis and genetic counseling challenging. In this review, we present the main genes implicated in non-syndromic human A/M phenotypes and, for practical purposes, classify them according to the most frequent or predominant phenotype each is associated with. Our intention is that this will allow clinicians to rank and prioritize their molecular analyses and interpretations according to the phenotypes of their patients.

Congenital Bilateral Anophthalmia: a Case Report and Review of Literature

Introduction:

Anophthalmia is congenital absence of the eyes; it may be unilateral or bilateral. Though rare, it occurs worldwide. It usually occurs in association with other systemic malformations.

Case report:

Therefore, the case of a female child delivered in University Clinic Center Tuzla is presented here with bilateral anophthalmia. The diagnosis was confirmed with an ocular computer tomography (CT) scan that showed under development of both globes within the orbit with a conclusion of bilateral anophthalmia. No other anomalies were found.

Conclusion:

This is unique case in the territory of Bosnia and Herzegovina, as according to the literature this is the first case of anophthalmia presented in this region. Currently two years ago she is followed both in ophthalmic and pediatric clinic at University Clinical Center in Tuzla.

An application of data mining to identify potential risk factors for anophthalmia and microphthalmia

BACKGROUND

We examined a large number of variables to generate new hypotheses regarding a wider range of risk factors for anophthalmia/microphthalmia using data mining.

METHODS

Data were from the National Birth Defects Prevention Study, a multicentre, case-control study from 10 centres in the United States. There were 134 cases of "isolated" and 87 "nonisolated" (with other major birth defects) of anophthalmia/microphthalmia and 11 052 nonmalformed controls with delivery dates October 1997-December 2011. Using random forest, a data mining procedure, we compared the two case types with controls for 201 variables. Variables considered important ranked by random forest were included in a multivariable logistic regression model to estimate odds ratios and 95% confidence intervals.

RESULTS

Predictors for isolated cases included paternal race/ethnicity, maternal intake of certain nutrients and foods, and childhood health problems in relatives. Using regression, inverse associations were observed with greater maternal education and with increasing intake of folate and potatoes. Odds were slightly higher with greater paternal education, for increased intake of carbohydrates and beans, and if relatives had a childhood health problem. For nonisolated cases, predictors included paternal race/ethnicity, maternal intake of certain nutrients, and smoking in the home the month before conception. Odds were higher for Hispanic fathers and smoking in the home and NSAID use the month before conception.

CONCLUSIONS

Results appear to support previously hypothesised risk factors, socio-economic status, NSAID use, and inadequate folate intake, and potentially provide new areas such as passive smoking pre-pregnancy, and paternal education and ethnicity, to explore for further understanding of anophthalmia/microphthalmia.

Mutation of IPO13 causes recessive ocular coloboma, microphthalmia, and cataract

Ocular coloboma is a developmental structural defect of the eye that often occurs as complex ocular anomalies. However, its genetic etiology remains largely unexplored. Here we report the identification of mutation (c.331C>T, p.R111C) in the IPO13 gene in a consanguineous family with ocular coloboma, microphthalmia, and cataract by a combination of whole-exome sequencing and homozygosity mapping. IPO13 encodes an importin-B family protein and has been proven to be associated with the pathogenesis of coloboma and microphthalmia. We found that Ipo13 was expressed in the cornea, sclera, lens, and retina in mice. Additionally, the mRNA expression level of Ipo13 decreased significantly in the patient compared with its expression in a healthy individual. Morpholino-oligonucleotide-induced knockdown of ipo13 in zebrafish caused dose-dependent microphthalmia and coloboma, which is highly similar to the ocular phenotypes in the patient. Moreover, both visual motor response and optokinetic response were impaired severely. Notably, these ocular phenotypes in ipo13-deficient zebrafish could be rescued remarkably by full-length ipo13 mRNA, suggesting that the phenotypes observed in zebrafish were due to insufficient ipo13 function. Altogether, our findings demonstrate, for the first time, a new role of IPO13 in eye morphogenesis and that loss of function of IPO13 could lead to ocular coloboma, microphthalmia, and cataract in humans and zebrafish.

In-depth genomic analysis of the family of a young man with severe visual impairment reveals a new gene involved in eye development. Ocular coloboma encompasses various hereditary disorders in which the eyes form improperly. Many of the underlying genetic factors remain unidentified. Researchers led by Zi-Bing Jin at Wenzhou Medical University in China sequenced the genes of 28-year-old man with a recessive form of ocular coloboma. By comparing these genetic data against equivalent genome sequences from his healthy parents, Jin’s team identified a gene called IPO13 as the culprit. IPO13 has not been linked to human disease before, but the researchers demonstrated that switching off IPO13 expression in zebrafish embryos gave rise to underdeveloped eyes with defects in the iris and cornea. These findings give clinicians another potential indicator for early diagnosis of ocular coloboma.

Nutrient intake in women before conception and risks of anophthalmia and microphthalmia in their offspring

BACKGROUND

We previously explored associations between nutrients including folate and other macro and micronutrients and risks of anophthalmia or microphthalmia in the National Birth Defects Prevention Study. In the current study, we expand those previous results with larger sample sizes and conduct analyses with an additional diet quality index using more recent data.

METHODS

The National Birth Defects Prevention Study is a population-based, multicenter case-control study of over 30 major birth defects, with estimated due dates from October 1997 to December 2011. Cases were 224 infants diagnosed with anophthalmia or microphthalmia. Controls were 11,109 live-born, nonmalformed infants randomly selected by each study center. Mothers completed a standardized, computer-assisted telephone interview between 6 weeks and 24 months after delivery. Mothers responded to a shortened food frequency questionnaire, assessing their nutrient intake for the year before pregnancy, and questions about periconceptional (2 months before to 2 months after conception) vitamin supplement use. Nutrient intake quartiles were based on the intake among controls.

RESULTS

Among vitamin supplement users, odds of anophthalmia/microphthalmia were decreased for women with intake levels in the highest quartile of folate (0.56, 95% confidence interval [CI] 0.32-0.98), magnesium (0.42, 95% CI 0.22-0.82), and vitamin E (0.50, 95% CI 0.29-0.89). Among women not reporting vitamin supplement use, the odds were significantly increased for beta-carotene (2.5, 95% CI 1.10-5.68) and decreased for retinol (0.37, 95% CI 0.19-0.73).

CONCLUSIONS

In this expanded analysis, we observed associations for a few nutrients, specifically forms of vitamin A. However, the heterogeneity of results by form and vitamin use necessitates further inquiry.

Report of an unsual case of anophthalmia and craniofacial cleft in a newborn with Toxoplasma gondii congenital infection

Background

We present one unusual case of anophthalmia and craniofacial cleft, probably due to congenital toxoplasmosis only.

Case presentation

A two-month-old male had a twin in utero who disappeared between the 7^th and the 14^th week of gestation. At birth, the baby presented anophthalmia and craniofacial cleft, and no sign compatible with genetic or exposition/deficiency problems, like the Wolf-Hirschhorn syndrome or maternal vitamin A deficiency. Congenital toxoplasmosis was confirmed by the presence of IgM abs and IgG neo-antibodies in western blot, as well as by real time PCR in blood. CMV infection was also discarded by PCR and IgM negative results. Structures suggestive of T. gondii pseudocysts were observed in a biopsy taken during the first functional/esthetic surgery.

Conclusions

We conclude that this is a rare case of anophthalmia combined with craniofacial cleft due to congenital toxoplasmosis, that must be considered by physicians. This has not been reported before.

Geographic clusters of congenital anomalies in Argentina

Geographical clusters are defined as the occurrence of an unusual number of cases higher than expected in a given geographical area in a certain period of time. The aim of this study was to identify potential geographical clusters of specific selected congenital anomalies (CA) in Argentina. The cases were ascertained from 703,325 births, examined in 133 maternity hospitals in the 24 provinces of Argentina. We used the spatial scan statistic to determine areas of Argentina which had statistically significant elevations of prevalence. Prenatal diagnosis followed by referral of high-risk pregnancies to high complexity hospitals in a hospital-based surveillance system can create artifactual clusters. We assessed the referral bias by evaluating the prevalence heterogeneity within each cluster. Eight clusters of selected CAs with unusually high birth prevalence were identified: anencephaly, encephalocele, spina bifida, diaphragmatic hernia, talipes equinovarus, omphalocele, Cleft lip with or without cleft palate (CL/P), and Down syndrome. The clusters of Down syndrome and CL/P observed in this study match the previously reported clusters. These findings support local targeted interventions to lower the prevalence of the CAs and/or further research on the cause of each cluster. The clusters of spina bifida, anencephaly, encephalocele, omphalocele, congenital diaphragmatic hernia, and talipes equinovarus may be influenced by prenatal diagnosis and referral to high complexity hospitals.

Digital Evaluation of Orbital Cyst Associated with Microphthalmos: Characteristics and Their Relationship with Orbital Volume

Purpose

To study the characteristics of orbital cyst associated with microphthalmos in a group of Chinese patients, and to analyze the relationship between orbital cyst and orbital volume.

Design

Cross-sectional comparative study.

Participants

120 patients who were diagnosed as unilateral clinical blind microphthalmos, in which 20 patients had orbital cyst in the affected eye.

Method

Participants had computed tomography (CT) scan. CT images were analyzed with a computer-aided software.

Main Outcome Measures

Volume and position of orbital cyst, microphthalmic to contralateral ratio (MCR) of orbital volume, height and depth and orbital rim displacement.

Results

38.1% of the cysts located anterior to or at the equator of the globe, 75% of which located infratemporally and all of which were outside the muscle cone. Most (84.6%) of the posterior cysts were inside the muscle cone. The anterior cysts were larger than the posterior cysts (p = 0.005). MCR of orbital volume (p<0.001), height (p = 0.004) and width (p = 0.043) were significantly higher in patients with orbital cyst than controls. For patients with orbital cyst, larger cyst-plus-globe volume of the affected eye was associated with higher MCR of orbital volume (r = 0.630, p = 0.003). Patients with large cyst-plus-globe volume had higher MCR of orbital volume (p = 0.002), height (p = 0.014), width (p = 0.005) and depth (p = 0.002) and less displacement in inferior (p = 0.004) orbital rim, compared with patients with small cyst-plus-globe volume, but the differences between patients with small cyst-plus-globe volume and patients without cyst were not significant.

Conclusions

Microphthalmic eyes with large cyst-plus-globe volume showed better similarity with the contralateral eyes, comparing with microphthalmic eyes without orbital cyst or with small cyst-plus-globe volume. It suggested that the existence of orbital cysts (especially large cysts) in microphthalmic eyes might play a positive role in the orbital development.

Disabling chronic conditions in childhood and socioeconomic disadvantage: a systematic review and meta-analyses of observational studies

OBJECTIVE

To determine the association of socioeconomic disadvantage with the prevalence of childhood disabling chronic conditions in high-income countries.

STUDY DESIGN

Systematic review and meta-analyses.

DATA SOURCES

6 electronic databases, relevant websites, reference lists and experts in the field.

STUDY SELECTION

160 observational studies conducted in high-income countries with data on socioeconomic status and disabling chronic conditions in childhood, published between 1 January 1991 and 31 December 2013.

DATA EXTRACTION AND SYNTHESIS

Abstracts were reviewed, full papers obtained, and papers identified for inclusion by 2 independent reviewers. Inclusion decisions were checked by a third reviewer. Where reported, ORs were extracted for low versus high socioeconomic status. For studies reporting raw data but not ORs, ORs were calculated. Narrative analysis was undertaken for studies without data suitable for meta-analysis.

RESULTS

126 studies had data suitable for meta-analysis. ORs for risk estimates were: all-cause disabling chronic conditions 1.72 (95% CI 1.48 to 2.01); psychological disorders 1.88 (95% CI 1.68 to 2.10); intellectual disability 2.41 (95% CI 2.03 to 2.86); activity-limiting asthma 2.20 (95% CI 1.87 to 2.85); cerebral palsy 1.42 (95% CI 1.26 to 1.61); congenital abnormalities 1.41 (95% CI 1.24 to 1.61); epilepsy 1.38 (95% CI 1.20 to 1.59); sensory impairment 1.70 (95% CI 1.39 to 2.07). Heterogeneity was high across most estimates (I(2)>75%). Of the 34 studies without data suitable for meta-analysis, 26 reported results consistent with increased risk associated with low socioeconomic status.

CONCLUSIONS

The findings indicate that, in high-income countries, childhood disabling chronic conditions are associated with social disadvantage. Although evidence of an association is consistent across different countries, the review provides limited evidence to explain the association; future research, using longitudinal data, will be required to distinguish low socioeconomic status as the cause or consequence of childhood disabling chronic conditions and the aetiological pathways and mechanisms.

Prenatal diagnosis of colobomatous microphthalmos

Optic nerve coloboma and microphthalmos with colobomatous cyst are rare congenital anomalies that are difficult to detect on prenatal ultrasonography and magnetic resonance imaging. Only four cases of optic nerve coloboma and two cases of microphthalmos with colobomatous cyst have been detected on prenatal imaging. The authors report a case of a fetus initially suspected to have retinoblastoma of the right eye on prenatal ultrasonography who was later diagnosed as having microphthalmos on fetal magnetic resonance imaging. Following delivery, she was noted to have microphthalmos with colobomatous cyst of the right eye and optic nerve coloboma of the left eye. The authors also review the prenatal ocular imaging findings of the differential diagnosis.

Testing for clustering at many ranges inflates family-wise error rate (FWE)

BACKGROUND

Testing for clustering at multiple ranges within a single dataset is a common practice in spatial epidemiology. It is not documented whether this approach has an impact on the type 1 error rate.

METHODS

We estimated the family-wise error rate (FWE) for the difference in Ripley's K functions test, when testing at an increasing number of ranges at an alpha-level of 0.05. Case and control locations were generated from a Cox process on a square area the size of the continental US (≈3,000,000 mi2). Two thousand Monte Carlo replicates were used to estimate the FWE with 95% confidence intervals when testing for clustering at one range, as well as 10, 50, and 100 equidistant ranges.

RESULTS

The estimated FWE and 95% confidence intervals when testing 10, 50, and 100 ranges were 0.22 (0.20 - 0.24), 0.34 (0.31 - 0.36), and 0.36 (0.34 - 0.38), respectively.

CONCLUSIONS

Testing for clustering at multiple ranges within a single dataset inflated the FWE above the nominal level of 0.05. Investigators should construct simultaneous critical envelopes (available in spatstat package in R), or use a test statistic that integrates the test statistics from each range, as suggested by the creators of the difference in Ripley's K functions test.

Microphthalmia in a case of Edward syndrome

AIM

To present an infant of trisomy 18 (Edwards Syndrome) with unilateral microphthalmia.

METHODS

A female infant who was born at 41 weeks of gestation had been diagnosed with Edwards Syndrome (ES). On ophthalmic examination, microphthalmia, microcornea, optic disc coloboma, and persistent hyaloid artery were determined in the left eye. In addition, abnormalities in the ears, hands, feet, and cardiovascular system were present.

DISCUSSION

With this case report, we aimed to highlight the relationship between ocular disgenesis and chromosomal disorders and the importance of prenatal testing and genetic counseling for parents.

Mutation of SALL2 causes recessive ocular coloboma in humans and mice

Ocular coloboma is a congenital defect resulting from failure of normal closure of the optic fissure during embryonic eye development. This birth defect causes childhood blindness worldwide, yet the genetic etiology is poorly understood. Here, we identified a novel homozygous mutation in the SALL2 gene in members of a consanguineous family affected with non-syndromic ocular coloboma variably affecting the iris and retina. This mutation, c.85G>T, introduces a premature termination codon (p.Glu29*) predicted to truncate the SALL2 protein so that it lacks three clusters of zinc-finger motifs that are essential for DNA-binding activity. This discovery identifies SALL2 as the third member of the Drosophila homeotic Spalt-like family of developmental transcription factor genes implicated in human disease. SALL2 is expressed in the developing human retina at the time of, and subsequent to, optic fissure closure. Analysis of Sall2-deficient mouse embryos revealed delayed apposition of the optic fissure margins and the persistence of an anterior retinal coloboma phenotype after birth. Sall2-deficient embryos displayed correct posterior closure toward the optic nerve head, and upon contact of the fissure margins, dissolution of the basal lamina occurred and PAX2, known to be critical for this process, was expressed normally. Anterior closure was disrupted with the fissure margins failing to meet, or in some cases misaligning leading to a retinal lesion. These observations demonstrate, for the first time, a role for SALL2 in eye morphogenesis and that loss of function of the gene causes ocular coloboma in humans and mice.

Phenanthrene causes ocular developmental toxicity in zebrafish embryos and the possible mechanisms involved

Recent studies show that polycyclic aromatic hydrocarbons (PAHs) may be a candidate cause of developmental defects of the retina, but the mechanism is still unclear. We evaluated the mechanism(s) underlying PAH-induced retinal development defects due to exposure to environmental concentrations of Phenanthrene (Phe) in zebrafish. We found that exposure to environmental concentrations of Phe caused obvious morphological changes, developmental retardation, apoptosis, and reduction of cell proliferation in the retina. Our results indicated that Phe could cause visual system developmental defects. Phe exposure up-regulated aryl hydrocarbon receptor (AhR) and microphthalmia-associated transcription factor (Mtif) expression, and down-regulated zinc finger E-box binding homeobox 1 (Zeb1) and paired box 6 (Pax6). Moreover, we demonstrated that AhR was a repressor of Zeb1. We propose that Phe's ocular toxicity is mediated by up-regulating AhR, which then down-regulates Zeb1, in turn inducing Mitf expression while inhibiting Pax6 expression.

Survey of microphthalmia in Japan

PURPOSE

To report the current status of patients with microphthalmia based on a cross-sectional survey of patient hospital visits.

METHODS

A questionnaire was sent to the departments of ophthalmology in 1,151 major Japanese hospitals to survey the following: the number of patients with microphthalmia who visited the outpatient clinics between January 2008 and December 2009; gender; age; family history; associated ocular anomalies; complications and systemic diseases; surgical treatment; vision and management. A retrospective quantitative registry of 1,254 microphthalmic eyes (851 patients) from 454 hospitals (39.4%) was compiled.

RESULTS

Of the patients for whom data were available, 50% ranged in age from 0 to 9 years. The major ocular findings were nanophthalmos, coloboma, and vitreoretinal malformations. Ocular complications frequently developed, including cataracts, glaucoma, and retinal detachment. Surgery was performed in 21.4% of all cases, and systemic diseases were present in 31% of all cases. The vision associated with microphthalmia exceeded 0.1 in about 30% of the eyes. Glasses and low vision aids were used by 21.6% of patients.

CONCLUSIONS

Patients with microphthalmia often have ocular and systemic anomalies. Early assessment and preservation of vision and long-term complication management are needed.

Parent-of-origin effects in SOX2 anophthalmia syndrome

PURPOSE

Sex determining region Y (SRY)-box 2 (SOX2) anophthalmia syndrome is an autosomal dominant disorder manifesting as severe developmental eye malformations associated with brain, esophageal, genital, and kidney abnormalities. The syndrome is usually caused by de novo mutations or deletions in the transcription factor SOX2. To investigate any potential parental susceptibility factors, we set out to determine the parent of origin of the mutations or deletions, and following this, to determine if birth order or parental age were significant factors, as well as whether mutation susceptibility was related to any sequence variants in cis with the mutant allele.

METHODS

We analyzed 23 cases of de novo disease to determine the parental origin of SOX2 mutations and deletions using informative single nucleotide polymorphisms and a molecular haplotyping approach. We examined parental ages for SOX2 mutation and deletion cases, compared these with the general population, and adjusted for birth order.

RESULTS

Although the majority of subjects had mutations or deletions that arose in the paternal germline (5/7 mutation and 5/8 deletion cases), there was no significant paternal bias for new mutations (binomial test, p=0.16) or deletions (binomial test, p=0.22). For both mutation and deletion cases, there was no significant association between any single nucleotide polymorphism allele and the mutant chromosome (p>0.05). Parents of the subjects with mutations were on average older at the birth of the affected child than the general population by 3.8 years (p=0.05) for mothers and 3.3 years (p=0.66) for fathers. Parents of the subjects with deletions were on average younger than the general population by 3.0 years (p=0.17) for mothers and 2.1 years (p=0.19) for fathers. Combining these data, the difference in pattern of parental age between the subjects with deletions and mutations was evident, with a difference of 6.5 years for mothers (p=0.05) and 5.0 years for fathers (p=0.22), with the mothers and fathers of subjects with mutations being older than the mothers and fathers of subjects with deletions. We observed that 14 of the 23 (61%) affected children were the first-born child to their mother, with 10/15 of the mutation cases (66%) and 4/8 deletion cases (50%) being first born. This is in comparison to 35% of births with isolated congenital anomalies overall who are first born (p=0.008).

CONCLUSIONS

Sporadic SOX2 mutations and deletions arose in both the male and female germlines. In keeping with several genetic disorders, we found that SOX2 mutations were associated with older parental age and the difference was statistically significant for mothers (p=0.05), whereas, although not statistically significant, SOX2 deletion cases had younger parents. With the current sample size, there was no evidence that sequence variants in cis surrounding SOX2 confer susceptibility to either mutations or deletions.

Clinical report of microphthalmia and optic nerve coloboma associated with a de novo microdeletion of chromosome 16p11.2

Anophthalmia and microphthalmia are etiologically and clinically heterogeneous. We present a 13-year-old boy with microphthalmia and multiple anomalies who was evaluated as part of our research into the etiology of microphthalmia. His clinical features included left microphthalmia, persistent hyperplastic primary vitreous and posterior coloboma, right posterior pole coloboma, pectus excavatum, mild hypotonia, mild delays in speech and motor development, and an anxiety disorder with social difficulties. Investigations with a chromosome microarray revealed a de novo deletion of chromosome 16p11.2 of approximately 882 kb in size. Deletions of this region of chromosome 16p11.2 are a newly delineated microdeletion syndrome, but this is the first report of microphthalmia and coloboma associated with monosomy for 16p11.2, and emphasizes the clinical variability that can be present with this deletion. This report contributes to the growing knowledge regarding this microdeletion and suggests that rare copy number changes may be a cause of microphthalmia and other eye anomalies.

Small area estimation of sparse disease counts using shared component models-application to birth defect registry data in New South Wales, Australia

In the field of disease mapping, little has been done to address the issue of analysing sparse health datasets. We hypothesised that by modelling two outcomes simultaneously, one would be able to better estimate the outcome with a sparse count. We tested this hypothesis utilising Bayesian models, studying both birth defects and caesarean sections using data from two large, linked birth registries in New South Wales from 1990 to 2004. We compared four spatial models across seven birth defects: spina bifida, ventricular septal defect, OS atrial septal defect, patent ductus arteriosus, cleft lip and or palate, trisomy 21 and hypospadias. For three of the birth defects, the shared component model with a zero-inflated Poisson (ZIP) extension performed better than other simpler models, having a lower deviance information criteria (DIC). With spina bifida, the ratio of relative risk associated with the shared component was 2.82 (95% CI: 1.46-5.67). We found that shared component models are potentially beneficial, but only if there is a reasonably strong spatial correlation in effect for the study and referent outcomes.

Association of a de novo 16q copy number variant with a phenotype that overlaps with Lenz microphthalmia and Townes-Brocks syndromes

BACKGROUND

Anophthalmia and microphthalmia are etiologically and clinically heterogeneous. Lenz microphthalmia is a syndromic form that is typically inherited in an X-linked pattern, though the causative gene mutation is unknown. Townes-Brocks syndrome manifests thumb anomalies, imperforate anus, and ear anomalies. We present a 13-year-old boy with a syndromic microphthalmia phenotype and a clinical diagnosis of Lenz microphthalmia syndrome.

CASE PRESENTATION

The patient was subjected to clinical and molecular evaluation, including array CGH analysis. The clinical features included left clinical anophthalmia, right microphthalmia, anteriorly placed anus with fistula, chordee, ventriculoseptal defect, patent ductus arteriosus, posteriorly rotated ears, hypotonia, growth retardation with delayed bone age, and mental retardation. The patient was found to have an approximately 5.6 Mb deletion of 16q11.2q12.1 by microarray based-comparative genomic hybridization, which includes the SALL1 gene, which causes Townes-Brocks syndrome.

CONCLUSIONS

Deletions of 16q11.2q12.2 have been reported in several individuals, although those prior reports did not note microphthalmia or anophthalmia. This region includes SALL1, which causes Townes-Brocks syndrome. In retrospect, this child has a number of features that can be explained by the SALL1 deletion, although it is not clear if the microphthalmia is a rare feature of Townes-Brocks syndrome or caused by other mechanisms. These data suggest that rare copy number changes may be a cause of syndromic microphthalmia allowing a personalized genomic medicine approach to the care of patients with these aberrations.

Clinical and genetic features of a dominantly-inherited microphthalmia pedigree from China

PURPOSE

To evaluate the clinical, histopathologic, and genetic characteristics of a microphthalmia pedigree.

METHODS

A five-generation Chinese family with microphthalmia was recruited. Clinical and histological examinations were performed in the affected patients and their family members. Cyrillic software was used to map the pedigree. Genomic DNA was extracted from peripheral blood, and linkage analysis was performed using short tandem repeat polymorphism markers. Two-point LOD scores were calculated using the MLINK program.

RESULTS

Microphthalmia was inherited in an autosomal dominant manner in this family. All nine affected members had hyperopia (mean: +8.00 diopters) and physiologically reduced axis oculi (mean: 19.29 mm) with a visual acuity of less than 0.5. Refractory angle-closure glaucoma occurred in three of them and atrophia bulbi in two. Histological examination showed diffuse degenerated collagen fibers in the scleral stroma. Two-point LOD score linkage analysis excluded all known genetic loci associated with simple microphthalmia in all patients.

CONCLUSIONS

Simple microphthalmia was dominantly inherited in this Chinese pedigree with typical phenotypes, which resulted in severe visual deterioration by middle age. A novel locus is predicted to be responsible for the microphthalmia in this family, which may prove a high genetic heterogeneity in microphthalmia.

Socio-occupational status and congenital anomalies

BACKGROUND

The aim of this study is to investigate the association between socio-occupational status and the frequency of major congenital anomalies in offspring.

METHODS

The study population comprised 81,435 live singletons born to mothers enrolled in the Danish National Birth Cohort between 1996 and 2002. A total of 3352 cases of major congenital anomalies (EUROCAT criteria) were identified by linkage to the National Hospital Discharge Register. Malformations were recorded at birth or in the first year of life. Information about maternal and paternal socio-occupational status was collected prospectively using telephone interviews in the second trimester of pregnancy and was categorized as high, middle or low. Associations were measured as relative prevalence ratios using the highest socio-occupational status within the couple as the reference group.

RESULTS

The prevalence of all recorded major congenital anomalies was similar, about 4%, in all the socio-occupational categories. Low social status of the couple did, however, correlate with a higher prevalence of congenital anomalies of the 'respiratory system'. No association was substantially attenuated when we adjusted for maternal and paternal age, smoking status, maternal alcohol habits, folic acid intake and body mass index. When malformations of the heart and the cardiovascular system were grouped together, they were more frequent in families where both parents presented a low socio-occupational status.

CONCLUSION

We detected an association between low socio-occupational status and congenital anomalies of the respiratory system, the heart and the circulatory system. These malformations are good candidates for a large study on occupational, environmental and social determinants.

Maternal demographic and socioeconomic characteristics of live-born infants with isolated ocular congenital abnormalities

PURPOSE

To evaluate maternal age and birth order, in addition socioeconomic status and finally occupational background of mothers who delivered babies with different isolated ocular congenital abnormalities.

METHODS

The data set of the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-2002 was used and the evaluation of maternal variables was based on both medical records and maternal information.

RESULTS

Mean maternal age and birth order was lower in the mothers of cases with isolated an/microphthalmia. The mean birth order was also lower in the mothers with isolated congenital cataract compared with the control groups. The mothers of cases with isolated coloboma had the usual mean maternal age with a very high proportion of second birth order. The proportion of unmarried women, low maternal socio-economic status and unemployment was larger in the groups of isolated an/microphthalmia and isolated primary congenital glaucoma and these mothers frequently worked in the agriculture.

CONCLUSIONS

Cases with different isolated ocular congenital abnormalities showed different maternal characteristics as the reference controls, therefore it is necessary to evaluate each isolated ocular congenital abnormality separately and maternal characteristics can be considered as potential confounders in the analyses of ocular congenital abnormalities.

Anophthalmia and microphthalmia

Anophthalmia and microphthalmia describe, respectively, the absence of an eye and the presence of a small eye within the orbit. The combined birth prevalence of these conditions is up to 30 per 100,000 population, with microphthalmia reported in up to 11% of blind children. High-resolution cranial imaging, post-mortem examination and genetic studies suggest that these conditions represent a phenotypic continuum. Both anophthalmia and microphthalmia may occur in isolation or as part of a syndrome, as in one-third of cases. Anophthalmia/microphthalmia have complex aetiology with chromosomal, monogenic and environmental causes identified. Chromosomal duplications, deletions and translocations are implicated. Of monogenic causes only SOX2 has been identified as a major causative gene. Other linked genes include PAX6, OTX2, CHX10 and RAX. SOX2 and PAX6 mutations may act through causing lens induction failure. FOXE3 mutations, associated with lens agenesis, have been observed in a few microphthalmic patients. OTX2, CHX10 and RAX have retinal expression and may result in anophthalmia/microphthalmia through failure of retinal differentiation. Environmental factors also play a contributory role. The strongest evidence appears to be with gestational-acquired infections, but may also include maternal vitamin A deficiency, exposure to X-rays, solvent misuse and thalidomide exposure. Diagnosis can be made pre- and post-natally using a combination of clinical features, imaging (ultrasonography and CT/MR scanning) and genetic analysis. Genetic counselling can be challenging due to the extensive range of genes responsible and wide variation in phenotypic expression. Appropriate counselling is indicated if the mode of inheritance can be identified. Differential diagnoses include cryptophthalmos, cyclopia and synophthalmia, and congenital cystic eye. Patients are often managed within multi-disciplinary teams consisting of ophthalmologists, paediatricians and/or clinical geneticists, especially for syndromic cases. Treatment is directed towards maximising existing vision and improving cosmesis through simultaneous stimulation of both soft tissue and bony orbital growth. Mild to moderate microphthalmia is managed conservatively with conformers. Severe microphthalmia and anophthalmia rely upon additional remodelling strategies of endo-orbital volume replacement (with implants, expanders and dermis-fat grafts) and soft tissue reconstruction. The potential for visual development in microphthalmic patients is dependent upon retinal development and other ocular characteristics.

Hsp90 selectively modulates phenotype in vertebrate development

Compromised heat shock protein 90 (Hsp90) function reveals cryptic phenotypes in flies and plants. These observations were interpreted to suggest that this molecular stress-response chaperone has a capacity to buffer underlying genetic variation. Conversely, the protective role of Hsp90 could account for the variable penetrance or severity of some heritable developmental malformations in vertebrates. Using zebrafish as a model, we defined Hsp90 inhibitor levels that did not induce a heat shock response or perturb phenotype in wild-type strains. Under these conditions the severity of the recessive eye phenotype in sunrise, caused by a pax6b mutation, was increased, while in dreumes, caused by a sufu mutation, it was decreased. In another strain, a previously unobserved spectrum of severe structural eye malformations, reminiscent of anophthalmia, microphthalmia, and nanophthalmia complex in humans, was uncovered by this limited inhibition of Hsp90 function. Inbreeding of offspring from selected unaffected carrier parents led to significantly elevated malformation frequencies and revealed the oligogenic nature of this phenotype. Unlike in Drosophila, Hsp90 inhibition can decrease developmental stability in zebrafish, as indicated by increased asymmetric presentation of anophthalmia, microphthalmia, and nanophthalmia and sunrise phenotypes. Analysis of the sunrise pax6b mutation suggests a molecular mechanism for the buffering of mutations by Hsp90. The zebrafish studies imply that mild perturbation of Hsp90 function at critical developmental stages may underpin the variable penetrance and expressivity of many developmental anomalies where the interaction between genotype and environment plays a major role.

Genetic variation is not always expressed as a single consistent phenotype even in familial diseases. Unilateral malformations in paired organs, such as the failure of an eye to develop on one side only, also remind us that gene function is often modified by environmental factors. Following observations by others in fruit flies, we explored the underlying mechanisms for such phenotypic fluctuation, using zebrafish as a vertebrate model. Earlier work suggested involvement of chaperone proteins like Hsp90, which assist with normal protein folding during development and also work overtime to keep proteins functional in response to environmental stress. Using specific drugs at defined times in early development for the limited reduction of Hsp90 activity, we showed that different cryptic genetic variants could be revealed consistently in genetically distinct fish strains. Once uncovered, the frequency of these variants was increased by inbreeding, confirming the role of underlying genetic factors. Similarly, we could modify the phenotypic severity of some—but not all—known gene variants, worsening some and improving others. It emerged that the most susceptible variants were those carrying amino acid alterations, in which assisted protein folding may either restore near normal function or facilitate malfunction, thus worsening phenotype. This insight may allow us to prevent recurrent malformations by minimizing or perhaps even counteracting the effects of exposure to environmental stress during development.

Ependymal tissue in microphthalmia with cyst

PURPOSE

To report the nature of the contents of a cyst associated with microphthalmia and optic nerve coloboma in a male infant.

DESIGN

Clinicopathologic report.

CASE REPORT

A male infant in good general health presented with a massively swollen, protruded left lower eyelid since birth. The globe was not identifiable. MRI disclosed a microphthalmic globe in the upper nasal orbit and an orbital cystic mass consisting of various compartments. Examination of the fellow eye showed a large optic nerve coloboma. As the protrusion of the left lower eyelid was progressive, aspiration of the cyst was performed twice. Finally, the cyst was removed surgically due to repeated filling.

RESULTS

Examination of the aspirated fluid showed resemblance to cerebrospinal fluid (CSF). During surgery, the cyst was not found to communicate with the cerebrospinal fluid system. However, tissue resembling choroidal plexus lined the wall of the cyst that was adherent to the optic nerve. Histological evaluation of the tissue revealed ependymal cells.

DISCUSSION

The presence of CSF in microphthalmic cysts does not necessarily imply a connection to the CNS, but may be due to local CSF production by ectopic ependymal cells.

Congenital bilateral microphthalmos after gestational syphilis

Congenital microphthalmos and anophthalmos are currently considered rare conditions. Many infectious agents have been previously associated with these pathologies, but rarely Treponema pallidum. We report a case of bilateral microphthalmos in which her mother presented gestational syphilis.

Changing pattern of childhood blindness in Maharashtra, India

AIM

To determine the causes of severe visual impairment and blindness in children in schools for the blind in Maharashtra, India.

METHODS

Children aged <16 years with a visual acuity of <6/60 in the better eye, attending 35 schools for the blind were examined between 2002 and 2005, and causes were classified using the World Health Organization's system.

RESULTS

1985 students were examined, 1778 of whom fulfilled the eligibility criteria. The major causes of visual loss were congenital anomalies (microphthalmos or anophthalmos; 735, 41.3%), corneal conditions (mainly scarring; 395, 22.2%), cataract or aphakia (n = 107, 6%), and retinal disorders (mainly dystrophies; n = 199, 11.2%). More than one third of children (34.5%) were blind from conditions which could have been prevented or treated, 139 of whom were referred for surgery. Low vision devices improved near-acuity in 79 (4.4%) children, and 72 (4%) benefited from refraction. No variation in causes by sex or region was observed.

CONCLUSIONS

Congenital anomalies accounted for 41% of blindness, which is higher than in a similar study conducted 10 years ago. Corneal scarring seems to be declining in importance, low vision and optical services need to be improved, and research is needed to determine the aetiology of congenital anomalies.

Descriptive epidemiology of anophthalmia and microphthalmia, Hawaii, 1986-2001

BACKGROUND

Population-based epidemiologic data on anophthalmia and microphthalmia in the United States are limited and have come mainly from only a few states. The intent of this study was to report on the epidemiology of these eye defects.

METHODS

Cases were derived from a population-based birth defects registry in Hawaii and comprised all infants and fetuses with anophthalmia and microphthalmia who were delivered during 1986-2001. Anophthalmia and microphthalmia rates per 10,000 births were determined for selected factors, and comparisons were made by calculating the rate ratios and 95% confidence intervals (CIs).

RESULTS

Ninety-six cases of anophthalmia and microphthalmia were identified, with a rate of 3.21 per 10,000 live births. The eye defects were isolated in 5 cases (5.2%), and 24 cases (25.0%) had confirmed chromosomal abnormalities. The risk of anophthalmia and microphthalmia varied over time and was significantly higher for live-born infants with low birth weights and gestational ages. The anophthalmia and microphthalmia rates also varied by maternal race/ethnicity, sex, and plurality, although these differences were not statistically significant.

CONCLUSIONS

Anophthalmia and microphthalmia frequently occurred with other birth defects, and the rate was consistent with that found in the literature. The risk of defects differed significantly with time period, birth weight, and gestational age. The impact of many factors on anophthalmia and microphthalmia in Hawaii was frequently consistent with that reported elsewhere.

Microphthalmia and brain atrophy: A novel neurodegenerative disease

OBJECTIVE

To delineate the features of a novel neurodegenerative disease.

METHODS

We report three children of three related families with congenital microphthalmia and blindness, and progressive spasticity, microcephaly, seizures, and profound mental retardation.

RESULTS

A magnetic resonance imaging scan was normal at birth. However, follow-up studies showed progressive atrophy involving the cerebral white matter and cortex, cerebellum, brainstem, and corpus callosum. The white matter changes extended into the subcortical region leaving only small islands of remaining cortical tissue. Known metabolic conditions involving white matter degeneration were excluded.

INTERPRETATION

We propose this to be a novel autosomal recessive neurodegenerative disorder to be coined MOBA (microphthalmia brain atrophy) disease.

Epidemiologic characteristics of anophthalmia and bilateral microphthalmia among 2.5 million births in California, 1989-1997

There is a paucity of epidemiologic information about the eye malformations anophthalmia and microphthalmia. Using data from a large population-based registry, we explored prevalences and maternal/infant characteristics associated with anophthalmia and bilateral microphthalmia. Data were derived from the California Birth Defects Monitoring Program, a population-based active surveillance system for collecting information on infants and fetuses with congenital malformations using multiple source ascertainment. Approximately 2.5 million births (liveborn and stillborn) occurred during the ascertainment period, 1989-1997. Information on maternal and infant/fetal characteristics was obtained from California birth certificate and fetal death files. The prevalence per 10,000 livebirths and stillbirths for anophthalmia was 0.18 and for bilateral microphthalmia was 0.22. These estimates reflect prevalences among births without chromosomal anomalies. Relative risks of anophthalmia were modestly higher among women aged 40 or more (relative risk = 2.0, 95% confidence interval 0.5-8.6). Risks were substantially lower for those mothers with >12 years of education, even after adjusting for other study factors, relative risk = 0.6 (0.2-1.7). The risk of anophthalmia was approximately twofold among multiple births compared to singletons. Similar to results for anophthalmia, decreased risks for bilateral microphthalmia were observed for maternal education of 12 years or more and increased risks observed for multiple births. These data show descriptive epidemiologic features of anophthalmia and bilateral microphthalmia.

Eye anomalies: seasonal variation and maternal viral infections

INTRODUCTION

Eye anomalies, including anophthalmos and microphthalmos (absent eye and small eye), are common features in congenital infection syndromes such as rubella. Influenza, Coxsackie virus, and Parvovirus are less well-established teratogens. We report an ecologic analysis of anophthalmia/microphthalmia prevalence in England in relation to temporal variation in these infections using routine infection data.

METHODS

The national (England) anophthalmos/microphthalmos register holds details of 406 babies (excluding chromosomal anomalies) born 1988-1994. Weekly infection data were obtained from the U.K. Public Health Laboratory Service and Royal College of General Practitioners Weekly Returns Service. We assigned cases and births an estimated exposure based on the population infection counts in the gestational weeks known to be critical for ocular development. We calculated the rate ratio of anophthalmos/microphthalmos prevalence for infection in the 90th percentile compared with the 10th percentile by Poisson regression.

RESULTS

There was a positive association between severe anophthalmos/microphthalmos prevalence and Parvovirus B19 (rate ratio = 1.26; 95% confidence interval = 1.00-1.58) and for influenza (1.41; 1.08-1.84). Coxsackie virus showed a negative association with any anophthalmos/microphthalmos (0.75; 0.58-0.98) and with severe cases (0.66; 0.46-0.95).

CONCLUSIONS

This analysis provides suggestive evidence for a teratogenic role of influenza and Parvovirus in anophthalmos/microphthalmos. The role of maternal infections in congenital anomaly etiology is worthy of further investigation.

SOX2anophthalmia syndrome

Heterozygous, de novo, loss-of-function mutations in SOX2 have been shown to cause bilateral anophthalmia. Here we provide a detailed description of the clinical features associated with SOX2 mutations in the five individuals with reported mutations and four newly identified cases (including the first reported SOX2 missense mutation). The SOX2-associated ocular malformations are variable in type, but most often bilateral and severe. Of the nine patients, six had bilateral anophthalmia and two had anophthalmia with contralateral microphthalmia with sclerocornea. The remaining case had anophthalmia with contralateral microphthalmia, posterior cortical cataract and a dysplastic optic disc, and was the only patient to have measurable visual acuity. The relatively consistent extraocular phenotype observed includes: learning disability, seizures, brain malformation, specific motor abnormalities, male genital tract malformations, mild facial dysmorphism, and postnatal growth failure. Identifying SOX2 mutations from large cohorts of patients with structural eye defects has delineated a new, clinically-recognizable, multisystem disorder and has provided important insight into the developmental pathways critical for morphogenesis of the eye, brain, and male genital tract.

Anophthalmia and microphthalmia in the Alberta Congenital Anomalies Surveillance System

BACKGROUND

A higher than expected rate of anophthalmia/microphthalmia (A/M) for 1999 was noted in both the Alberta Congenital Anomalies Surveillance System (ACASS) and the Canadian Congenital Anomalies Surveillance System (CCASS). Since this increase was at variance with the previous 19 years, we performed a review to determine whether the increase was true and, if so, the possible explanation.

METHODS

We reviewed the records of the cases of A/M in the ACASS together with the accompanying attachments (e.g., consultant, autopsy and chromosome reports) for 1991-2001. In addition, we contacted all 91 registered ophthalmologists in Alberta. Letters were also written to the Edmonton and Calgary offices of the Canadian National Institute for the Blind (CNIB).

RESULTS

Sixty cases of A/M were ascertained over the study period. Of the 88 active ophthalmologists in the province, 21 (24%) replied, but no new cases were ascertained from this source. No replies were received from the CNIB. We constructed five categories of clinical phenotypes for the 60 cases: 20 had a chromosomal etiology, 13 had a recognized syndrome or association, 16 had extraocular malformations, 5 had other eye anomalies, and 6 had A/M only. Pregnancy terminations were not included. The higher rate in 1999 was mainly due to cases with a chromosomal etiology or a recognized syndrome or association. There was no indication that a teratogen was causing a cluster of A/M cases, as our annual rates were comparable to those for other jurisdictions not only in Canada but also in other countries.

INTERPRETATION

Our review confirmed that the rate of A/M in Alberta in 1999 was high but that the increase was mainly due to five cases of trisomy 13 together with one case associated with a syndrome (Meckel-Gruber). Our findings provide reassurance that there was no environmental cause of clustering of anophthalmia or microphthalmia. This review demonstrates the importance of ongoing population-based surveillance in providing baseline birth prevalence rates for evaluating trends and clusters.

Association of anophthalmia and esophageal atresia: Four new cases identified by the anophthalmia/microphthalmia clinical registry

We report four new cases of the rare association of anophthalmia and esophageal atresia. There are only nine cases previously reported in the literature with this association. Our cases appear to be distinct from those already reported, thus increasing the number of cases to thirteen. Advances in developmental biology have shown that mutations in developmental genes active early in embryogenesis can lead to birth defects in multiple, seemingly unrelated systems. The network of genes that directs development has been highly conserved through evolution. Several transcription factors have been shown to be important in regulating eye development. Mutations in these developmental genes may be the cause of this clinical association.

Epidemiologic approaches to identifying environmental causes of birth defects

Epidemiology can be used to elucidate environmental causes of birth defects. This paper discusses 1) different types of environmental causes; 2) the difficulties in comparing the prevalence of birth defects between populations, including the need for a population base and the implications of prenatal diagnosis; 3) the main study designs for observational epidemiological studies and the various sources of bias; 4) how statistical power can be increased by meta-analysis or multicentric studies, and improved grouping of birth defects into etiologically more homogeneous subgroups; 5) the distinction between association and causation; 6) the interpretation of clusters in time and space in relation to local environmental causes; and 7) the potential of genetic epidemiology to help elucidate environmental causes. While further research continues into the environmental causes of birth defects, the epidemiologic evidence base for policy making and clinical practice is poor in many areas. The epidemiologic approach is important not only to elucidate environmental causes but also to assess the implementation of existing research into policy and practice for the prevention of birth defects.

14q(22) deletion in a familial case of anophthalmia with polydactyly

We report a family of anophthalmia with ocular and extraocular manifestations. The proband, his three sisters, and two sons had anophthalmia and preaxial polydactyly in the right hand. Cytogenetic analysis was done for the proband and two of his sons, one of whom was affected. Another male child was affected but was not available for cytogenetic analysis. Karyotypes of both affected individuals showed deletion on long arm of 14q22q23. Literature review shows four cases of anophthalmia with extra ocular anomalies associated with 14q (q22q23) deletion. Recently it has been suggested that the human homeobox gene, SIX6, and the BMP-4 gene are responsible for eye development. Both are located in the chromosome 14q22.3-q23 region. Deletion in this region has been known to be associated with anophthalmia and pituitary anomalies. This is the first family of anophthalmia, which showed polydactyly with a chromosomal deletion in the 14q22-q23 region and its familial transmission in two generations with a total of six affected individuals.

The management of orbital cysts associated with congenital microphthalmos and anophthalmos

AIMS

To study the management of the orbital cysts present in a group of patients with anophthalmos and microphthalmos.

METHODS

A retrospective study of 34 patients (40 orbits) treated for orbital cyst associated with microphthalmos and anophthalmos.

RESULTS

The two largest treatment groups comprised 17 orbits (42.5%) where the cyst was removed surgically and 17 orbits (42.5%) where the cyst was retained and conformers were used. The remaining cases comprised two orbits (5%) where the cyst was aspirated initially; two orbits (5%) with large cysts which will need to be excised after further orbital growth; one orbit (2.5%) in which a silicone expander was used initially, and one orbit (2.5%) in which a mildly microphthalmic eye had some vision and was monitored but required no surgery.

CONCLUSION

In this study 33 out of 34 patients had a good cosmetic result which illustrates that the orbital cyst in microphthalmos or anophthalmos performs a useful role in socket expansion and that the majority of patients with this condition can expect a good cosmetic outcome.

[Treatment of congenital clinical anophthalmos with high hydrophilic hydrogel expanders]

INTRODUCTION

Children presenting with congenital anophthalmos usually develop a smaller bony orbit, a constricted mucosal socket, and a shortened eyelid fissure. This causes problems when fitting these patients with a prosthesis. Clinical evaluation of the Wiese self-inflating hydrogel expanders has demonstrated their ability to expand the socket and eyelid fissure for inserting a more realistic prosthesis in shorter periods of time.

PATIENTS AND METHOD

The study included 13 consecutive anophthalmic patients, eight unilateral and five bilateral. Each patient received a hemispherical osmotic tissue expander in the rudimentary mucosal socket and later a sphere implanted in the deeper soft orbital tissue.

RESULTS

The use of hydrogel expanders enlarged the lid and palpebral fissure in all children, with good cosmetic results. It allowed insertion of custom-made glass prostheses with good cosmetic appearance very early in life. Growth of the bony orbit may be stimulated successfully by these expanders in the soft orbital tissue.

CONCLUSIONS

The enlargement of constricted mucosal sockets and short palpebral fissures using self-inflating hydrogel expanders is a new and successful concept in treating congenital anophthalmos.

Environmental risk factors in congenital malformations of the eye

Developmental eye defects such as coloboma are a significant cause of visual morbidity in children, and are more common in India than elsewhere. The possible role of environmental factors in the aetiology of these conditions was investigated by studying birth order, symptoms of vitamin A deficiency (night blindness), drug use and maternal illness in pregnancy, rubella antibodies and exposure to agricultural chemicals. Through hospital records and community-based rehabilitation programmes in Andhra Pradesh, children with colobomata were recruited from schools for the blind. Eighty-three mothers of affected children were interviewed. The results showed that 43% of parents were consanguineous, that 19% had a positive family history and that the frequency of coloboma was highest in second-born children. Eleven (16%) mothers had a history of night blindness while pregnant with the affected child; seven (8%) took medication during the 1st trimester, abortifacients in two cases; three reported fever in the 1st trimester; and 11 (13%) reported exposure to agricultural chemicals.