Novel loci for ocular axial length identified through extreme-phenotype genome-wide association study in Chinese populations

PURPOSE

To investigate genetic loci associated with ocular axial length (AL) in the Chinese population.

METHODS

A genome-wide association study meta-analysis was conducted in totalling 2644 Chinese individuals from 3 cohorts: the Guangzhou cohort (GZ, 537 high myopes and 151 hyperopes), Wenzhou cohort (334 high myopes and 6 hyperopes) and Guangzhou Twin Eye Study (1051 participants with normally distributed AL). Functional mapping was performed to annotate the significant signals, possible tissues and cell types by integrating available multiomics data. Logistic regression models using AL-associated SNPs were constructed to predict three AL status in GZ.

RESULTS

Two novel loci (1q25.2 FAM163A and 7p22.2 SDK1) showed genome-wide significant associations with AL, together explaining 29.63% of AL variance in GZ. The two lead SNPs improved the prediction accuracy for AL status, especially for hyperopes. The frequencies of AL decreasing (less myopic) alleles of the two SNPs were lowest in East Asians as compared with other populations (rs17370084: f EAS=0.03, f EUR=0.24, f AFR=0.05; rs73046501: f EAS=0.06, f EUR=0.07, f AFR=0.20), which was in line with the global distribution of myopia. The cerebral cortex and gamma-aminobutyric acidergic interneurons showed possible functional involvement in myopia development, and the galactose metabolic pathways were significantly enriched.

CONCLUSION

Our study identified two population-specific novel loci for AL, expanding our understanding of the genetic basis of AL and providing evidence for a role of the nervous system and glucose metabolism in myopia pathogenesis.

Ocular manifestations in a cohort of 43 patients with KBG syndrome

Ophthalmological conditions are underreported in patients with KBG syndrome, which is classically described as presenting with dental, developmental, intellectual, skeletal, and craniofacial abnormalities. This study analyzed the prevalence of four ophthalmological conditions (strabismus, astigmatism, myopia, hyperopia) in 43 patients with KBG syndrome carrying variants in ANKRD11 or deletions in 16q24.3 and compared it to the literature. Forty-three patients were recruited via self-referral or a private Facebook group hosted by the KBG Foundation, with 40 of them having pathogenic or likely pathogenic variants. Virtual interviews were conducted to collect a comprehensive medical history verified by medical records. From these records, data analysis was performed to calculate the prevalence of ophthalmological conditions. Out of the 40 participants with pathogenic or likely pathogenic variants, strabismus was reported in 9 (22.5%) participants, while astigmatism, myopia, and hyperopia were reported in 11 (27.5%), 6 (15.0%), and 8 (20.0%) participants, respectively. Other reported conditions include anisometropia, amblyopia, and nystagmus. When compared to the literature, the prevalence of strabismus and refractive errors is higher than other studies. However, more research is needed to determine if variants in ANKRD11 play a role in abnormal development of the visual system. In patients with established KBG syndrome, screening for misalignment or refractive errors should be done, as interventions in patients with these conditions can improve functioning and quality of life.

Association of hyperopia with incident clinically significant depression: epidemiological and genetic evidence in the middle-aged and older population

AIMS

To investigate the association between hyperopia and clinically significant depression (CSD) in middle-aged and older individuals. The effect of genetic determinants of hyperopia on incident CSD was also explored.

METHODS

We included participants who had available data on mean spherical equivalent (MSE) and were free of depression at baseline from the UK Biobank. For the phenotypic association, hyperopia was defined as MSE of+2.00 dioptres (D) or greater, and was divided into mild, moderate and high groups. Diagnosis of CSD across follow-up was determined based on electronic hospital inpatients records. For the genetic association analysis, the association between hyperopia Polygenic Risk Score and incident CSD was assessed. Mendelian randomisation was assessed for causality association.

RESULTS

Over a median follow-up of 11.11 years (IQR: 10.92-11.38), hyperopia was significantly associated with incident CSD independent of genetic risk (HR 1.29, 95% CI 1.05 to 1.59) compared with emmetropia participants, especially in those hyperopic patients without optical correction (HR 1.38, 95% CI 1.07 to 1.76). In addition, participants in the high degree of hyperopia were more likely to have incident CSD than participants in the mild degree of hyperopia (P for trend=0.009). Genetic analyses did not show any significant associations between hyperopia and incident CSD (p≥0.1).

CONCLUSIONS

Hyperopia was significantly associated with an increased risk of incident CSD. This was independent of genetic predisposition to hyperopia, emphasising the importance of regular vision screening and correction of hyperopia to reduce the risk of CSD regardless of genetic risk.

Phenotypic consequences of a nanophthalmos-associated TMEM98 variant in human and mouse

Nanophthalmos is characterised by shorter posterior and anterior segments of the eye, with a predisposition towards high hyperopia and primary angle-closure glaucoma. Variants in TMEM98 have been associated with autosomal dominant nanophthalmos in multiple kindreds, but definitive evidence for causation has been limited. Here we used CRISPR/Cas9 mutagenesis to recreate the human nanophthalmos-associated TMEM98 p.(Ala193Pro) variant in mice. The p.(Ala193Pro) variant was associated with ocular phenotypes in both mice and humans, with dominant inheritance in humans and recessive inheritance in mice. Unlike their human counterparts, p.(Ala193Pro) homozygous mutant mice had normal axial length, normal intraocular pressure, and structurally normal scleral collagen. However, in both homozygous mice and heterozygous humans, the p.(Ala193Pro) variant was associated with discrete white spots throughout the retinal fundus, with corresponding retinal folds on histology. This direct comparison of a TMEM98 variant in mouse and human suggests that certain nanophthalmos-associated phenotypes are not only a consequence of a smaller eye, but that TMEM98 may itself play a primary role in retinal and scleral structure and integrity.

Truncation mutations in MYRF underlie primary angle closure glaucoma

Mutations in myelin regulatory factor (MYRF), a gene mapped to 11q12-q13.3, are responsible for autosomal dominant high hyperopia and seem to be associated with angle closure glaucoma, which is one of the leading causes of irreversible blindness worldwide. Whether there is a causal link from the MYRF mutations to the pathogenesis of primary angle-closure glaucoma (PACG) remains unclear at this time. Six truncation mutations, including five novel and one previously reported, in MYRF are identified in seven new probands with hyperopia, of whom all six adults have glaucoma, further confirming the association of MYRF mutations with PACG. Immunofluorescence microscopy demonstrates enriched expression of MYRF in the ciliary body and ganglion cell layer in humans and mice. Myrf^mut/+ mice have elevated IOP and fewer ganglion cells along with thinner retinal nerve fiber layer with ganglion cell layer than wild-type. Transcriptome sequencing of Myrf^mut/+ retinas shows downregulation of Dnmt3a, a gene previously associated with PACG. Co-immunoprecipitation demonstrates a physical association of DNMT3A with MYRF. DNA methylation sequencing identifies several glaucoma-related cell events in Myrf^mut/+ retinas. The interaction between MYRF and DNMT3A underlies MYRF-associated PACG and provides clues for pursuing further investigation into the pathogenesis of PACG and therapeutic target.

Association of CX36 Protein Encoding Gene GJD2 with Refractive Errors

Purpose: This study aimed to evaluate the associations of GJD2 (rs634990, rs524952) and RASGRF1 (rs8027411, rs4778879, rs28412916) gene polymorphisms with refractive errors. Methods: The study included 373 subjects with refractive errors (48 myopia, 239 myopia with astigmatism, 14 hyperopia, and 72 hyperopia with astigmatism patients) and 104 ophthalmologically healthy subjects in the control group. A quantitative real-time polymerase chain reaction (qPCR) method was chosen for genotyping. Statistical calculations and analysis of results were performed with IBM SPSS Statistics 27 software. Results: The correlations in monozygotic (MZ) twin pairs were higher compared to DZ pairs, indicating genetic effects on hyperopia and astigmatism. The heritability (h2) of hyperopia and astigmatism was 0.654 for the right eye and 0.492 for the left eye. The GJD2 rs634990 TT genotype increased the incidence of hyperopia with astigmatism by 2.4-fold and the CT genotype decreased the incidence of hyperopia with astigmatism by 0.51-fold (p < 0.05). The GJD2 rs524952 AT genotype reduced the incidence of hyperopia with astigmatism by 0.53-fold (p < 0.05). Haplotype analysis of SNPs in the GJD2 gene revealed two statistically significant haplotypes: ACTAGG for rs634990 and TTTAGA for rs524952, which statistically significantly reduced the incidence of hyperopia and hyperopia with astigmatism by 0.41-fold (95% CI: 0.220−0.765) and 0.383-fold (95% CI: 0.199−0.737), respectively (p < 0.05). It was also found that, in the presence of haplotypes ACTAGG for rs634990 and TATAGA for rs524952, the possibility of hyperopia was reduced by 0.4-fold (p < 0.05). Conclusions: the heritability of hyperopia and hyperopia with astigmatism was 0.654−0.492, according to different eyes in patients between 20 and 40 years. The GJD2 rs634990 was identified as an SNP, which has significant associations with the co-occurrence of hyperopia and astigmatism. Patients with the GJD2 gene rs634990 TT genotype were found to have a 2.4-fold higher risk of develop hyperopia with astigmatism.

[Chinese expert consensus on the reference interval of ocular hyperopia reserve, axial length, corneal curvature and genetic factors in school-age children (2022)]

Myopia is a focal issue affecting the eye health of children and adolescents in China. Hyperopia reserve is the refractive state before the occurrence of myopia. As the result of dynamic matching between the axial length, cornea and lens, it is of great significance to the prevention and control of myopia. There has been a lack of the reference basis for children's eyeball development parameters and the influence of genetic factors, especially the changing law of the above-mentioned parameters in the process of children's "emmetropization". To promote the prevention and control of myopia in children and adolescents and to standardize population screening and clinical treatment, based on the survey data of refractive errors in children and adolescents from different regions, a consensus has been reached on the reference interval of hyperopia reserve, axial length and corneal curvature and related genetic factors of emmetropia at different ages among school-age children by the Public Health Ophthalmology Branch of the Chinese Preventive Medicine Association.

Glaucoma Syndromes: Insights into Glaucoma Genetics and Pathogenesis from Monogenic Syndromic Disorders

Monogenic syndromic disorders frequently feature ocular manifestations, one of which is glaucoma. In many cases, glaucoma in children may go undetected, especially in those that have other severe systemic conditions that affect other parts of the eye and the body. Similarly, glaucoma may be the first presenting sign of a systemic syndrome. Awareness of syndromes associated with glaucoma is thus critical both for medical geneticists and ophthalmologists. In this review, we highlight six categories of disorders that feature glaucoma and other ocular or systemic manifestations: anterior segment dysgenesis syndromes, aniridia, metabolic disorders, collagen/vascular disorders, immunogenetic disorders, and nanophthalmos. The genetics, ocular and systemic features, and current and future treatment strategies are discussed. Findings from rare diseases also uncover important genes and pathways that may be involved in more common forms of glaucoma, and potential novel therapeutic strategies to target these pathways.

Changes in ocular motility in Kabuki syndrome

Kabuki syndrome is a rare genetic disorder, caused by mutation in the KMT2D or KDM6A genes, which affects several organs in the majority of patients, among which are the eyes. The most typical clinical characteristics are mental retardation, postnatal growth retardation, skeletal anomalies, and characteristic facial features. As the eyes are affected in most of the cases, ophthalmological examination is recommended for the early detection of ocular anomalies, in order to prevent visual impairment. The most frequent ocular signs are strabismus, ptosis, and refractive anomalies. A series of cases of Kabuki syndrome is described in five children, four of whom exhibited strabismus with esotropia, over action of inferior oblique muscles, and under action of superior oblique muscles associated with a V pattern. Most published papers do not report or might underestimate the ocular problems. It may be appropriate to perform orbital magnetic resonances in order to detect changes in the muscle paths that are related to the pathology of the eye movements found.

Variants in myelin regulatory factor (MYRF) cause autosomal dominant and syndromic nanophthalmos in humans and retinal degeneration in mice

Nanophthalmos is a rare, potentially devastating eye condition characterized by small eyes with relatively normal anatomy, a high hyperopic refractive error, and frequent association with angle closure glaucoma and vision loss. The condition constitutes the extreme of hyperopia or farsightedness, a common refractive error that is associated with strabismus and amblyopia in children. NNO1 was the first mapped nanophthalmos locus. We used combined pooled exome sequencing and strong linkage data in the large family used to map this locus to identify a canonical splice site alteration upstream of the last exon of the gene encoding myelin regulatory factor (MYRF c.3376-1G>A), a membrane bound transcription factor that undergoes autoproteolytic cleavage for nuclear localization. This variant produced a stable RNA transcript, leading to a frameshift mutation p.Gly1126Valfs*31 in the C-terminus of the protein. In addition, we identified an early truncating MYRF frameshift mutation, c.769dupC (p.S264QfsX74), in a patient with extreme axial hyperopia and syndromic features. Myrf conditional knockout mice (CKO) developed depigmentation of the retinal pigment epithelium (RPE) and retinal degeneration supporting a role of this gene in retinal and RPE development. Furthermore, we demonstrated the reduced expression of Tmem98, another known nanophthalmos gene, in Myrf CKO mice, and the physical interaction of MYRF with TMEM98. Our study establishes MYRF as a nanophthalmos gene and uncovers a new pathway for eye growth and development.

Gene expression in response to optical defocus of opposite signs reveals bidirectional mechanism of visually guided eye growth

Myopia (nearsightedness) is the most common eye disorder, which is rapidly becoming one of the leading causes of vision loss in several parts of the world because of a recent sharp increase in prevalence. Nearwork, which produces hyperopic optical defocus on the retina, has been implicated as one of the environmental risk factors causing myopia in humans. Experimental studies have shown that hyperopic defocus imposed by negative power lenses placed in front of the eye accelerates eye growth and causes myopia, whereas myopic defocus imposed by positive lenses slows eye growth and produces a compensatory hyperopic shift in refractive state. The balance between these two optical signals is thought to regulate refractive eye development; however, the ability of the retina to recognize the sign of optical defocus and the composition of molecular signaling pathways guiding emmetropization are the subjects of intense investigation and debate. We found that the retina can readily distinguish between imposed myopic and hyperopic defocus, and identified key signaling pathways underlying retinal response to the defocus of different signs. Comparison of retinal transcriptomes in common marmosets exposed to either myopic or hyperopic defocus for 10 days or 5 weeks revealed that the primate retina responds to defocus of different signs by activation or suppression of largely distinct pathways. We also found that 29 genes differentially expressed in the marmoset retina in response to imposed defocus are localized within human myopia quantitative trait loci (QTLs), suggesting functional overlap between genes differentially expressed in the marmoset retina upon exposure to optical defocus and genes causing myopia in humans. These findings identify retinal pathways involved in the development of myopia, as well as potential new strategies for its treatment.

The worldwide prevalence of myopia is predicted to increase from the current 23% to about 50% in the next three decades. Although much effort has been directed towards elucidating the mechanisms underlying refractive eye development and myopia, treatment options for myopia are mostly limited to optical correction, which does not prevent progression of myopia nor the pathological blinding complications often associated with the disease. Several experimental optics-based treatments have had only limited effect on myopia progression, and currently available drug treatments are limited and the mechanisms of action are not well understood. The development of safe and effective pharmacological treatments for myopia is urgently needed to prevent the impending myopia epidemic. The main obstacles that prevent the development of anti-myopia drugs are the uncertainties regarding the mechanisms controlling eye growth and optical development, including the molecular signaling pathways underlying it. In this study, we show that, contrary to the conventional thinking that myopic and hyperopic defocus trigger opposite changes in the same genes and pathways to guide postnatal eye growth, defocus of opposite signs affect eye growth via largely distinct retinal pathways. Knowing that myopic and hyperopic defocus signals drive eye growth in opposite directions and propagate via different pathways provides a framework for the development of new anti-myopia drugs. Myopia can be controlled pharmacologically by stimulating pathways underlying the retinal response to positive lenses and/or by suppressing pathways underlying the retinal response to negative lenses.

Müller glia-derived PRSS56 is required to sustain ocular axial growth and prevent refractive error

A mismatch between optical power and ocular axial length results in refractive errors. Uncorrected refractive errors constitute the most common cause of vision loss and second leading cause of blindness worldwide. Although the retina is known to play a critical role in regulating ocular growth and refractive development, the precise factors and mechanisms involved are poorly defined. We have previously identified a role for the secreted serine protease PRSS56 in ocular size determination and PRSS56 variants have been implicated in the etiology of both hyperopia and myopia, highlighting its importance in refractive development. Here, we use a combination of genetic mouse models to demonstrate that Prss56 mutations leading to reduced ocular size and hyperopia act via a loss of function mechanism. Using a conditional gene targeting strategy, we show that PRSS56 derived from Müller glia contributes to ocular growth, implicating a new retinal cell type in ocular size determination. Importantly, we demonstrate that persistent activity of PRSS56 is required during distinct developmental stages spanning the pre- and post-eye opening periods to ensure optimal ocular growth. Thus, our mouse data provide evidence for the existence of a molecule contributing to both the prenatal and postnatal stages of human ocular growth. Finally, we demonstrate that genetic inactivation of Prss56 rescues axial elongation in a mouse model of myopia caused by a null mutation in Egr1. Overall, our findings identify PRSS56 as a potential therapeutic target for modulating ocular growth aimed at preventing or slowing down myopia, which is reaching epidemic proportions.

Isotope-coded protein label based quantitative proteomic analysis reveals significant up-regulation of apolipoprotein A1 and ovotransferrin in the myopic chick vitreous

This study used isotope-coded protein label (ICPL) quantitative proteomics and bioinformatics analysis to examine changes in vitreous protein content and associated pathways during lens-induced eye growth. First, the vitreous protein profile of normal 7-day old chicks was characterized by nano-liquid chromatography electrospray ionization tandem mass spectrometry. A total of 341 unique proteins were identified. Next, myopia and hyperopia were induced in the same chick by attaching -10D lenses to the right eye and +10D lenses to the left eye, for 3 and 7 days. Protein expression in lens-induced ametropic eyes was analyzed using the ICPL approach coupled to LCMS. Four proteins (cystatin, apolipoprotein A1, ovotransferrin, and purpurin) were significantly up-regulated in the vitreous after 3 days of wearing -10D lenses relative to +10D lens contralateral eyes. The differences in protein expression were less pronounced after 7 days when the eyes approached full compensation. In a different group of chicks, western blot confirmed the up-regulation of apolipoprotein A1 and ovotransferrin in the myopic vitreous relative to both contralateral lens-free eyes and hyperopic eyes in separate animals wearing +10D lenses. Bioinformatics analysis suggested oxidative stress and lipid metabolism as pathways involved in compensated ocular elongation.

APLP2 Regulates Refractive Error and Myopia Development in Mice and Humans

Myopia is the most common vision disorder and the leading cause of visual impairment worldwide. However, gene variants identified to date explain less than 10% of the variance in refractive error, leaving the majority of heritability unexplained (“missing heritability”). Previously, we reported that expression of APLP2 was strongly associated with myopia in a primate model. Here, we found that low-frequency variants near the 5’-end of APLP2 were associated with refractive error in a prospective UK birth cohort (n = 3,819 children; top SNP rs188663068, p = 5.0 × 10⁻⁴) and a CREAM consortium panel (n = 45,756 adults; top SNP rs7127037, p = 6.6 × 10⁻³). These variants showed evidence of differential effect on childhood longitudinal refractive error trajectories depending on time spent reading (gene x time spent reading x age interaction, p = 4.0 × 10⁻³). Furthermore, Aplp2 knockout mice developed high degrees of hyperopia (+11.5 ± 2.2 D, p < 1.0 × 10⁻⁴) compared to both heterozygous (-0.8 ± 2.0 D, p < 1.0 × 10⁻⁴) and wild-type (+0.3 ± 2.2 D, p < 1.0 × 10⁻⁴) littermates and exhibited a dose-dependent reduction in susceptibility to environmentally induced myopia (F(2, 33) = 191.0, p < 1.0 × 10⁻⁴). This phenotype was associated with reduced contrast sensitivity (F(12, 120) = 3.6, p = 1.5 × 10⁻⁴) and changes in the electrophysiological properties of retinal amacrine cells, which expressed Aplp2. This work identifies APLP2 as one of the “missing” myopia genes, demonstrating the importance of a low-frequency gene variant in the development of human myopia. It also demonstrates an important role for APLP2 in refractive development in mice and humans, suggesting a high level of evolutionary conservation of the signaling pathways underlying refractive eye development.

Gene variants identified by GWAS studies to date explain only a small fraction of myopia cases because myopia represents a complex disorder thought to be controlled by dozens or even hundreds of genes. The majority of genetic variants underlying myopia seems to be of small effect and/or low frequency, which makes them difficult to identify using classical genetic approaches, such as GWAS, alone. Here, we combined gene expression profiling in a monkey model of myopia, human GWAS, and a gene-targeted mouse model of myopia to identify one of the “missing” myopia genes, APLP2. We found that a low-frequency risk allele of APLP2 confers susceptibility to myopia only in children exposed to large amounts of daily reading, thus, providing an experimental example of the long-hypothesized gene-environment interaction between nearwork and genes underlying myopia. Functional analysis of APLP2 using an APLP2 knockout mouse model confirmed functional significance of APLP2 in refractive development and implicated a potential role of synaptic transmission at the level of glycinergic amacrine cells of the retina for the development of myopia. Furthermore, mouse studies revealed that lack of Aplp2 has a dose-dependent suppressive effect on susceptibility to form-deprivation myopia, providing a potential gene-specific target for therapeutic intervention to treat myopia.

[Characteristics of refractive status of mutant Lumican transgenic mice]

OBJECTIVE

To investigate the change of refractive status in transgenic mice with mutant Lumican (bright proteoglycan) gene at different ages.

METHODS

Experimental Study. Fifty-four 3-week-old with mutant Lumican gene (cDNA 596T > C) mice (27 male and 27 female) were randomly divided into 9 groups (n = 6, half male and half female) by random number table. One group (3-week-old) was randomly chosen and measured the refractive status by retinoscopy after mydriasis. Measurement of other groups were repeated the method above respectively in the fourth, fifth, sixth, eighth, tenth, twelfth, sixteenth, and twentieth week. Differences of diopter between right and left eye and between male and female were compared within each group by paired t test. The differences of mice's diopters in different age were compared by Kruskal-Wallis H test. Pairwise comparisons were acquired by Mann-Whitney U test.

RESULTS

There were no statistic difference of diopters between binoculus: The mice's diopters of right and left eyes were respective measured in the twentieth week (1.50 ± 0.45) D and (1.25 ± 0.42) D (t = -0.889, P > 0.05), The mice's diopters of right and left eyes were respective measured in the third week (-2.50 ± 2.59) D and (-2.50 ± 4.32) D (t = 0.000, P > 0.05); There were no statistic difference of diopters between different genders: The mice's diopters of female and male were respective measured in the third week (-0.5 ± 3.83) D and (-4.17 ± 1.94) D, (t = 2.079, P > 0.05), The mice's diopters of female and male were respective measured in the twelfth week (1.50 ± 0.84) D and (1.50 ± 1.87) D (t = 0.000, P > 0.05); Analysis of binocular diopters revealed significant differences among nine groups (H = 20.910, P < 0.05). Diopters measured in the third week (-2.50 ± 3.40D) and the sixth week (+3.25 ± 2.67) D had statistical difference (Z = -3.259, P < 0.001). There were no statistical significance between other groups (P > 0.001).

CONCLUSIONS

Characteristics of diopters gathered from mice with Lumican gene mutation at different weeks are summarized as follows: Myopia could be observed in the third week. And this situation of myopia was gradually transformed into hyperopia with aging. The maximum hyperopic diopter was observed at 6th-week-old mice. From the eighth to twentieth week, the degree of hyperopic diopter gradually decreased and stabilized.

Genome-wide meta-analysis of myopia and hyperopia provides evidence for replication of 11 loci

Refractive error (RE) is a complex, multifactorial disorder characterized by a mismatch between the optical power of the eye and its axial length that causes object images to be focused off the retina. The two major subtypes of RE are myopia (nearsightedness) and hyperopia (farsightedness), which represent opposite ends of the distribution of the quantitative measure of spherical refraction. We performed a fixed effects meta-analysis of genome-wide association results of myopia and hyperopia from 9 studies of European-derived populations: AREDS, KORA, FES, OGP-Talana, MESA, RSI, RSII, RSIII and ERF. One genome-wide significant region was observed for myopia, corresponding to a previously identified myopia locus on 8q12 (p = 1.25×10⁻⁸), which has been reported by Kiefer et al. as significantly associated with myopia age at onset and Verhoeven et al. as significantly associated to mean spherical-equivalent (MSE) refractive error. We observed two genome-wide significant associations with hyperopia. These regions overlapped with loci on 15q14 (minimum p value = 9.11×10⁻¹¹) and 8q12 (minimum p value 1.82×10⁻¹¹) previously reported for MSE and myopia age at onset. We also used an intermarker linkage- disequilibrium-based method for calculating the effective number of tests in targeted regional replication analyses. We analyzed myopia (which represents the closest phenotype in our data to the one used by Kiefer et al.) and showed replication of 10 additional loci associated with myopia previously reported by Kiefer et al. This is the first replication of these loci using myopia as the trait under analysis. “Replication-level” association was also seen between hyperopia and 12 of Kiefer et al.'s published loci. For the loci that show evidence of association to both myopia and hyperopia, the estimated effect of the risk alleles were in opposite directions for the two traits. This suggests that these loci are important contributors to variation of refractive error across the distribution.

Novel membrane frizzled-related protein gene mutation as cause of posterior microphthalmia resulting in high hyperopia with macular folds

PURPOSE

We present a genetic and clinical analysis of two sisters, 3 and 4 years of age, with nanophthalmos and macular folds.

METHODS

Ophthalmological examination, general paediatric examination and molecular genetic analysis of the MFRP gene were performed in both affected siblings.

RESULTS

Clinical analysis showed high hyperopia (+11 D and +12 D), short axial lengths (15 mm) and the presence of macular folds and optic nerve head drusen. Autofluorescence of the retina was generally normal with subtle macular abnormalities. Sequence analysis showed compound heterozygosity for severe MFRP mutations in both sisters: a previously reported p.Asn167fs (c.498dupC) and a novel stop codon mutation p.Gln91X (c.271C>T).

CONCLUSION

These are the youngest nanophthalmos patients in the literature identified with severe loss of MFRP function, showing already the known structural abnormalities for this disease. Adult patients affected by homozygous or compound heterozygous MFRP mutations generally show signs of retinal dystrophy, with ERG disturbances and RPE abnormalities on autofluorescence imaging. ERG examination could not be performed in these children, but extensive RPE abnormalities were not seen at this young age.

Biometric and molecular characterization of clinically diagnosed posterior microphthalmos

PURPOSE

To biometrically and molecularly characterize clinically diagnosed posterior microphthalmos.

DESIGN

Prospective case series.

METHODS

Twenty-five affected patients from 13 families diagnosed by ophthalmologists experienced with the condition at the King Khaled Eye Specialist Hospital were studied. All participants underwent axial length measurement, keratometry, corneal pachymetry, and candidate gene analysis (MFRP, PRSS56). Main outcome measures were the results of ocular biometry and gene analysis.

RESULTS

All patients (2-47 years of age) had high hyperopia, normal-appearing anterior segments, posterior chamber foreshortening, and characteristic papillomacular folds/wrinkles. For the right eye, mean cycloplegic refraction was +15.09 diopters (D) (range 9.88-18.75). Axial length (mean 16.25 mm [range 14.88-19.88]) had strong inverse correlation (Pearson coefficient -0.88, P < .0001) with corneal power (mean 48.89 D [range 41.91-52.25]) and a positive correlation with corneal diameter (Pearson 0.64, P = .001). Corneal thickness and anterior chamber dimensions were within normal ranges. Left eye data were similar. Nineteen Saudi patients (8/13 families) harbored 4 different homozygous PRSS56 mutations, 1 Indian and 1 Saudi patient harbored 2 different homozygous MFRP mutations, and 4 Saudi patients (3/13 families) had no detectable mutation in either gene. Patients with MFRP mutations were not clinically different from patients with PRSS56 mutations or no identified mutation. Truncating PRSS56 mutations were associated with shorter axial lengths (mean 15.72 mm) than missense PRSS56 mutations (mean 16.37 mm) or no identified mutation (mean 17.57 mm).

CONCLUSIONS

These data define posterior microphthalmos biometrically and reveal that corneal steepening proportional to the degree of axial foreshortening is part of the phenotype. Corneal diameter decreases with decreasing axial length, suggesting posterior microphthalmos and nanophthalmos represent a spectrum of high hyperopia rather than distinct phenotypes. In the Saudi population PRSS56 mutations are the major cause, and in our cohort truncating mutations were associated with a more severe phenotype.

Hereditary High Hypermetropia in the Faroe Islands

PURPOSE

To characterize the phenotype of two families with high hypermetropia from the Faroe Islands.

METHODS

Ophthalmologic evaluation including ultrasound oculometry and anthropometric measurements.

RESULTS

Of the 40 examined family members, 15 individuals (8 males, 7 females; ages: 6-77 years; mean: 36.5 years) had small deep-set eyes with high hypermetropia (median: + 16.5 D; range: + 7.75 to + 22), short axial eye length (< 21 mm), and a thickened eye wall. The median corrected visual acuity was 0.4 (0.2-0.9). Ocular complications included angle-closure glaucoma in six eyes, uveal effusion in three eyes, cataract in two eyes, and esotropia with amblyopia in three eyes. An emergency case of uveal effusion and retinal detachment after Yag iridotomy eventually responded to systemic corticosteroids and scleral resection surgery with a slow visual recovery. No associated ocular or systemic malformations were found in the series. In addition to the two examined families, six smaller Faroese families with high hypermetropia are briefly reported.

CONCLUSIONS

The study highlights the signs and symptoms of a rare hereditary phenotype characterized by a short axial length mainly confined to the posterior segment of the eye, a shallow anterior chamber, and a thickened eye wall. The morphological characteristics predispose for sight-threatening complications such as angle-closure glaucoma, chorioretinal pathology including uveal effusion, and amblyopia. Regular ophthalmic follow-up is therefore of obvious importance in families known to have small eyes/high hypermetropia. An endemic high prevalence in the Faroe Islands suggests the presence of a founder effect, and further genetic research would probably indicate pseudodominant rather than dominant transmission

[Retinitis pigmentosa--clinical and genetic aspects with low vision]

PURPOSE

Clinical and genetic study of a case of retinitis pigmentosa following the vision and the quality of life in this disease.

METHOD

This paper presents a female periodically reevaluated in our clinic from the first diagnosis of retinitis pigmentosa which was established ten years ago, with many relatives with the diagnosis of retinitis pigmentosa, has also high hyperopia and optic disc drusen. A particular aspect--she is student at English Faculty and she want to become professor in a school for children with low vision. Clinical evaluation included complete ophthalmic and general examination, family history and also some additional lab and imaging study, In genetic evaluation of this case were used the basic rules of genetics to diagnose the genetic form of retinitis pigmentosa in order to offer a correct genetic counseling.

CONCLUSIONS

Retinitis pigmentosa needs a broad clinical evaluation and a careful socio-professional rehabilitation of these low-vision patients.

Heritability and familial aggregation of refractive error in the Old Order Amish

PURPOSE

To determine the heritability of refractive error and familial aggregation of myopia and hyperopia in an elderly Old Order Amish (OOA) population.

METHODS

Nine hundred sixty-seven siblings (mean age, 64.2 years) in 269 families were recruited for the Amish Eye Study in the Lancaster County area of Pennsylvania. Refractive error was determined by noncycloplegic manifest refraction. Heritability of refractive error was estimated with multivariate linear regression as twice the residual sibling-sibling correlation after adjustment for age and gender. Logistic regression models were used to estimate the sibling recurrence odds ratio (OR(s)). Myopia and hyperopia were defined with five different thresholds.

RESULTS

The age- and gender-adjusted heritability of refractive error was 70% (95% CI: 48%-92%) in the OOA. Age and gender-adjusted OR(s) and sibling recurrence risk (lambda(s)), with different thresholds defining myopia ranged from 3.03 (95% CI: 1.58-5.80) to 7.02 (95% CI: 3.41-14.46) and from 2.36 (95% CI: 1.65-3.19) to 5.61 (95% CI: 3.06-9.34). Age and gender-adjusted OR(s) and lambda(s) for different thresholds of hyperopia ranged from 2.31 (95% CI: 1.56-3.42) to 2.94 (95% CI: 2.04-4.22) and from 1.33 (95% CI: 1.22-1.43) to 1.85 (95% CI: 1.18-2.78), respectively. Women were significantly more likely than men to have hyperopia. There was no significant gender difference in the risk of myopia.

CONCLUSIONS

In the OOA, refractive error is highly heritable. Hyperopia and myopia aggregate strongly in OOA families.

Refractive findings in children with astigmatic parents: the Sydney Myopia Study

PURPOSE

To examine the impact of parental astigmatism on astigmatic error and ocular biometric parameters in children.

DESIGN

Population-based cross-sectional study.

METHODS

Six-year-old children (n = 1,741; 78.9% response) and 12-year-old children (n = 2,367; 75.3% response) underwent a comprehensive eye examination, including cycloplegic autorefraction and ocular biometry. Astigmatism was determined in parents from spectacle prescriptions, which were supplied for 468 children.

RESULTS

The prevalence of astigmatism in six-year-old children with astigmatic parents was not significantly different from that of those without astigmatic parents (6.8% vs 2.8%); corresponding rates for 12-year-old children were 9.5% and 7.8% (both P > .05). No significant differences in mean cylinder and in ocular biometric parameters were observed between children with astigmatic parents and those with no astigmatic parents.

CONCLUSIONS

Parental astigmatism was not associated with a higher prevalence of childhood astigmatism and did not seem to have a significant impact on measures of ocular biometric parameters in children.

Stapes ankylosis in a family with a novel NOG mutation: otologic features of the facioaudiosymphalangism syndrome

OBJECTIVE

To report the phenotype-genotype correlation in a Belgian family that was ascertained to have a novel missense mutation in the NOG gene mapping to chromosome 17q22.

STUDY DESIGN

To describe the phenotype, a retrospective case study was performed based on the otologic, audiologic, ophthalmologic, and radiologic data of the mutation carriers of the NOG gene.

SETTING

Tertiary referral center.

PATIENTS

All members of a Belgian kindred who carried the novel missense mutation in the NOG gene (NOG, Trp205Cys [W205C]; 1426G>C).

INTERVENTIONS

Diagnostic otologic and ophthalmologic examination, audiometric analysis, and radiologic imaging.

MAIN OUTCOME MEASURES

Phenotype-genotype correlations.

RESULTS

All five mutation carriers had a typical facies. Bilateral proximal symphalangism and hyperopia were present in 80%. Five of 10 ears also had progressive early-onset conductive hearing loss caused by stapes ankylosis.

CONCLUSIONS

So far, 14 independent NOG mutations have been identified. The autosomal dominant disorder described in the present family was caused by a novel NOG missense mutation (NOG, Trp205Cys [W205C]; 1426G>C). The phenotype correlated well with the facioaudiosymphalangism syndrome. The mutation carriers demonstrated progressive multiple joint fusions, hyperopia, early-onset conductive deafness, and a typical facies.

A G1103R mutation in CRB1 is co-inherited with high hyperopia and Leber congenital amaurosis

PURPOSE

To identify the genetic basis of recessive inheritance of high hyperopia and Leber congenital amaurosis (LCA) in a family of Middle Eastern origin.

MATERIALS AND METHODS

The patients were examined using standard ophthalmic techniques. DNA samples were obtained and genetic linkage was carried out using polymorphic markers flanking the known genes and loci for LCA. Exons were amplified and sequenced.

RESULTS

All four members of this family affected by LCA showed high to extreme hyperopia, with average spherical refractive errors ranging from +5.00 to +10.00. Linkage was obtained to 1q31.3 with a maximal LOD score of 5.20 and a mutation found in exon 9 of the CRB1 gene, causing a G1103R substitution at a highly conserved site in the protein. CRB1 is a vertebrate homolog of the Drosophila crumbs gene, which is required for photoreceptor morphogenesis, and has been associated with either retinitis pigmentosa (RP) or LCA. This sequence variant has previously been reported as a compound heterozygote in one sporadic LCA patient.

CONCLUSION

Although hyperopia has been associated with LCA, it is typically moderate and variable between patients with the same mutation. In addition, some CRB1 mutations can be associated with either RP or LCA. We have shown that hyperopia and LCA are linked to the mutant CRB1 gene itself and are not dependent on unlinked modifiers.

Changes in scleral MMP-2, TIMP-2 and TGFbeta-2 mRNA expression after imposed myopic and hyperopic defocus in chickens

Induction of myopia leads to a decreased glycosaminoglycan synthesis and smaller collagen fibrillar diameters, increased levels of gelatinase-A (MMP-2) and decreased amounts of tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) in the fibrous sclera of both chicks and tree shrews. Another factor found to be involved in altered eye growth is the transforming growth factor beta-2 (TGFbeta-2). The aim of the current study was to measure MMP-2, TIMP-2 and TGFbeta-2 mRNA expression changes separately in the two scleral layers of chicks, following myopic and hyperopic defocus. Chicks were treated unilaterally with positive and negative lenses for different time periods. All contralateral eyes wore plano lenses and additional controls, treated binocularly with plano lenses, were included. Real-time PCR was used to measure MMP-2, TIMP-2 and TGFbeta-2 mRNA levels. Few changes in MMP-2 and TIMP-2 mRNA levels were measured following treatment with plus and minus lenses for up to 3 days. The mRNA levels of MMP-2 and TIMP-2 were either unchanged or co-regulated in both eyes, even though only the eye with the powered lens actually displayed changes in growth. In contrast, TGFbeta-2 mRNA was significantly up-regulated in the cartilaginous layer following treatment with plus lenses after 24 hr, compared to all other groups. These changes were confined to the eyes that also displayed reduced growth, suggesting a role of TGFbeta-2 in the final steps of visual eye growth regulation.

Extreme hyperopia is the result of null mutations in MFRP, which encodes a Frizzled-related protein

Nanophthalmos is a rare disorder of eye development characterized by extreme hyperopia (farsightedness), with refractive error in the range of +8.00 to +25.00 diopters. Because the cornea and lens are normal in size and shape, hyperopia occurs because insufficient growth along the visual axis places these lensing components too close to the retina. Nanophthalmic eyes show considerable thickening of both the choroidal vascular bed and scleral coat, which provide nutritive and structural support for the retina. Thickening of these tissues is a general feature of axial hyperopia, whereas the opposite occurs in myopia. We have mapped recessive nanophthalmos to a unique locus at 11q23.3 and identified four independent mutations in MFRP, a gene that is selectively expressed in the eye and encodes a protein with homology to Tolloid proteases and the Wnt-binding domain of the Frizzled transmembrane receptors. This gene is not critical for retinal function, as patients entirely lacking MFRP can still have good refraction-corrected vision, produce clinically normal electro-retinograms, and show only modest anomalies in the dark adaptation of photoreceptors. MFRP appears primarily devoted to regulating axial length of the eye. It remains to be determined whether natural variation in its activity plays a role in common refractive errors.

Familial aggregation of hyperopia in an elderly population of siblings in Salisbury, Maryland

PURPOSE

To determine whether hyperopia aggregates in families in an older mixed-race population.

DESIGN

Cross-sectional familial aggregation study using sibships.

METHODS

We recruited 759 subjects (mean age, 73.4 years) in 241 families through the population-based Salisbury Eye Evaluation study. Subjects underwent noncycloplegic refraction if best-corrected visual acuity (BCVA) was <or=20/40, had lensometry to measure their currently worn spectacles if BCVA was >20/40 with spectacles, or were considered to be plano (refraction of zero) if the BCVA was >20/40 without spectacles. Preoperative refraction from medical records was used for bilaterally pseudophakic subjects.

RESULTS

Utilizing hyperopia cutoffs from 1.00 to 2.50 diopters, age-, race-, and gender-adjusted odds ratios for hyperopia with an affected sibling ranged from 2.72 (95% confidence interval [CI], 1.84-4.01) to 4.87 (95% CI, 2.54-9.30). The odds of hyperopia increased with age until 75 years, after which they remained relatively constant. Black men were significantly less likely to be hyperopic than white men, white women, or black women.

CONCLUSIONS

Hyperopia appears to be under strong genetic control in this older population.

Teunissen-Cremers Syndrome: A Clinical, Surgical, and Genetic Report

OBJECTIVE

To describe clinical and radiologic features, results of ear surgery, and genetic analysis in three families with Teunissen-Cremers syndrome.

DESIGN

Case series.

SETTING

Tertiary referral center.

BACKGROUND

The NOG gene encodes the protein noggin, which has antagonist action in osteogenesis. Malformation of bones and joints may result from defects in noggin. Teunissen-Cremers syndrome is caused by mutations in the NOG gene. Two mutations in this gene were reported previously. The proximal symphalangism-hearing impairment syndrome, also caused by mutations in the NOG gene, is characterized by proximal symphalangism, conductive hearing loss, and occasionally synostoses.

METHODS

We examined nine affected members of three Dutch families. Reconstructive middle ear surgery was performed in five patients (nine ears), and we sequenced the NOG gene in these families.

RESULTS

Affected members had conductive hearing impairment, hyperopia, and broad thumbs and first toes with brachytelephalangia. Surgery manifested stapes ankylosis with additional incudal fixation frequently in the fossa incudis. Air-bone gaps decreased to less than 10 dB in six ears. Genetic analysis revealed three new mutations in the NOG gene.

CONCLUSION

The Teunissen-Cremers syndrome is an entity in its clinical presentation, distinct from other syndromes with proximal symphalangism and hearing impairment. So far, in five families with Teunissen-Cremers syndrome, four truncating mutations and one amino acid substitution were found in the NOG gene. The majority of other mutations found in this gene are missense mutations, which might result in some residual protein activity. Reconstructive middle ear surgery is an option for treatment.

Oculometric Characteristics of Extreme Hypermetropia in Two Faroese Families

PURPOSE

To describe and analyze the oculometric features of small eyes with high hypermetropia in two Faroese families, with emphasis on refractive components.

METHODS

Members of the two families (N=40; age, 1 to 77 years), including 15 cases of extreme hypermetropia (+7.5 to +19.25 D), had an ophthalmic evaluation including refractometry, keratometry, and axial ocular measurements using A-scan ultrasound. Eye-wall thickness was assessed using B-scan. Nonparametric statistics were used, mainly the Mann-Whitney U test.

RESULTS

In the two families, there were six and nine probands, respectively, with hypermetropia more than +7 D and short eyes as defined by axial eye lengths <21 mm. The median corrected visual acuity was 0.4 (range, 0.2 to 0.9). Gross fundus abnormalities were not observed. All 15 had a short posterior segment with a thick eye wall and a relatively thick lens. Furthermore, steep and rather small corneas were present. In one of the families, 70% of the affected had a corneal curvature radius of < or =7.0 mm. Five probands from family 2 were labeled as possibly affected because of hypermetropia and borderline axial length findings (21 to 22 mm). The remaining 20 subjects had visual acuity and oculometric findings within physiologic limits.

CONCLUSIONS

The axial measurement features in our series of highly hypermetropic eyes mainly presented as an extension downward from the hypermetropic bottom line of the normal distribution. The axial shortness of the eyes was primarily the result of a short posterior eye segment ("posterior microphthalmos"). A steep cornea was a feature in most small eyes in our series, particularly in one family branch.

Refractive evaluation in children with growth defect

PURPOSE

Growth hormone (GH) is considered essential for postnatal somatic growth, exerting its effects on growth by hepatic production of IGF-I. IGF and other growth factors interact with the developing ocular tissues by influencing the synthesis of the extracellular matrix of the sclera and by inducing angiogenesis. The association between optic nerve hypoplasia, reduced retinal vascularization and GH deficiency (GHD) is well known. The purpose of this study is to evaluate the possible influence of congenital GHD on the refraction and on the emmetropization process.

METHODS

Eighty children with congenital GHD had a thorough ophthalmologic examination, including cycloplegic refraction and axial length measurement. As a control group we enrolled 483 healthy children.

RESULTS

In accordance with other epidemiological studies, the control group showed a slightly myopic mean defect; on the contrary, in GHD group we found a hyperopic defect, related to a shorter axial length, with statistically significant differences.

CONCLUSIONS

Our findings emphasise the possible role of growth hormone in ocular development, and its interaction with the physiological process of emmetropization.

Shared mutations in NR2E3 in enhanced S-cone syndrome, Goldmann-Favre syndrome, and many cases of clumped pigmentary retinal degeneration

OBJECTIVES

To determine if enhanced s-cone syndrome (ESCS), Goldmann-Favre syndrome (GFS), and clumped pigmentary retinal degeneration (CPRD) are caused by mutations in the NR2E3 gene and to characterize the clinical findings in patients with NR2E3 mutations. Patients One patient with ESCS, one with GFS, and 20 with CPRD.

METHODS

The coding regions of the NR2E3 and NRL genes and part of the THRB1 coding region were scanned for mutations using single-strand conformation and direct sequencing methods. We evaluated visual acuity, refractive error, visual fields, fundi, final dark-adaptation thresholds, and electroretinograms (ERGs).

RESULTS

The patients with ESCS and GFS and 9 of the 20 unrelated patients with CPRD had mutations in the NR2E3 gene. Six mutations were found in these 11 patients, including 2 novel mutations: the missense mutation Ala256Glu and the frameshift mutation Pro276del17 (the first obviously null allele reported). Three patients were mutant homozygotes, and 8 had 2 mutations. All but one of the mutations in the patients with ESCS and GFS were also found in patients with CPRD. All NR2E3 cases were hyperopes and had retinal vascular attenuation and reduced and delayed full-field ERGs. Clumped pigment deposits were recognized in the patients with ESCS and GFS. The CPRD patients without NR2E3 mutations had no detected mutations in NRL or THRB1.

CONCLUSIONS

We found that ESCS, GFS, and CPRD can all have the same genetic basis. Clinical Relevance The combination of night blindness, hyperopia, and clumped retinal pigment deposits should raise the suspicion that a patient has NR2E3 disease.

Autosomal dominant stapes ankylosis with broad thumbs and toes, hyperopia, and skeletal anomalies is caused by heterozygous nonsense and frameshift mutations in NOG, the gene encoding noggin

Although fixation of the stapes is usually progressive and secondary to otosclerosis, it may present congenitally, with other skeletal manifestations, as an autosomal dominant syndrome-such as proximal symphalangism (SYM1) or multiple-synostoses syndrome (SYNS1), both of which are caused by mutations in NOG, the gene encoding noggin. We describe a family that was ascertained to have nonsyndromic otosclerosis but was subsequently found to have a congenital stapes ankylosis syndrome that included hyperopia, a hemicylindrical nose, broad thumbs and great toes, and other minor skeletal anomalies but lacked symphalangism. A heterozygous nonsense NOG mutation-c.328C-->T (Q110X), predicted to truncate the latter half of the protein-was identified, and a heterozygous insertion in NOG-c.252-253insC, in which the frameshift is predicted to result in 96 novel amino acids before premature truncation-was identified in a previously described second family with a similar phenotype. In contrast to most NOG mutations that have been reported in kindreds with SYM1 and SYNS1, the mutations observed in these families with stapes ankylosis without symphalangism are predicted to disrupt the cysteine-rich C-terminal domain. These clinical and molecular findings suggest that (1) a broader range of conductive hearing-loss phenotypes are associated with NOG mutations than had previously been recognized, (2) patients with sporadic or familial nonsyndromic otosclerosis should be evaluated for mild features of this syndrome, and (3) NOG alterations should be considered in conductive hearing loss with subtle clinical and skeletal features, even in the absence of symphalangism.

Genes and environment in refractive error: the twin eye study

PURPOSE

A classical twin study was performed to examine the relative importance of genes and environment in refractive error.

METHODS

Refractive error was examined in 226 monozygotic (MZ) and 280 dizygotic (DZ) twin pairs aged 49 to 79 years (mean age, 62.4 years). Using a Humphrey-670 automatic refractor, continuous measures of spherical equivalent, total astigmatism, and corneal astigmatism were recorded. Univariate and bivariate maximum likelihood model fitting was used to estimate genetic and environmental variance components using information from both eyes.

RESULTS

For the continuous spectrum of myopia/hyperopia, a model specifying additive genetic and unique environmental factors showed the best fit to the data, yielding a heritability of 84% to 86% (95% confidence interval [CI], 81%-89%). If myopia and hyperopia (< or = -0.5 D and > or = 0.5 D, respectively) were treated as binary traits, the heritability was 90% (95% CI, 81%-95%) for myopia and 89% (95% CI, 81%-94%) for hyperopia. For total and corneal astigmatism, modeling showed dominant genetic effects are important; dominant genetic effects accounted for 47% to 49% of the variance of total astigmatism (95% CI, 37%-55%) and 42% to 61% of corneal astigmatism variance (95% CI, 8%-71%), with additive genetic factors accounting for 1% to 4% and 4% to 18%, respectively (95% CIs, 0%-13% and 0%-60%, respectively).

CONCLUSIONS

Genetic effects are of major importance in myopia/hyperopia; astigmatism appears to be dominantly inherited.

Congenital stapes ankylosis, broad thumbs, and hyperopia: report of a family and refinement of a syndrome

We report on a family with conductive hearing loss due to congenital stapes ankylosis, and with hyperopia, broad thumbs, and broad first toes. Neither of the studied relatives had symphalangism, possibly distinguishing this syndrome as an entity separate from the facio-audio-symphalangism and proximal symphalangism syndromes. An alternative possibility is that this family falls within the spectrum of the facioaudio-symphalangism and proximal symphalangism syndromes. Visualization of the ossicular chain, and ophthalmologic and radiologic studies are important in the evaluation of families with congenital conductive hearing loss. A characteristic physiognomy in our patients is present; this autosomal dominant syndrome was first described by Teunissen and Cremers [1990: Laryngoscope 100:380-384].

Autosomal dominant nanophthalmos (NNO1) with high hyperopia and angle-closure glaucoma maps to chromosome 11

Nanophthalmos is an uncommon developmental ocular disorder characterized by a small eye, as indicated by short axial length, high hyperopia (severe farsightedness), high lens/eye volume ratio, and a high incidence of angle-closure glaucoma. We performed clinical and genetic evaluations of members of a large family in which nanophthalmos is transmitted in an autosomal dominant manner. Ocular examinations of 22 affected family members revealed high hyperopia (range +7.25-+13.00 diopters; mean +9.88 diopters) and short axial length (range 17.55-19.28 mm; mean 18.13 mm). Twelve affected family members had angle-closure glaucoma or occludable anterior-chamber angles. Linkage analysis of a genome scan demonstrated highly significant evidence that nanophthalmos in this family is the result of a defect in a previously unidentified locus (NNO1) on chromosome 11. The gene was localized to a 14.7-cM interval between D11S905 and D11S987, with a maximum LOD score of 5. 92 at a recombination fraction of .00 for marker D11S903 and a multipoint maximum LOD score of 6.31 for marker D11S1313. NNO1 is the first human locus associated with nanophthalmos or with an angle-closure glaucoma phenotype, and the identification of the NNO1 locus is the first step toward the cloning of the gene. A cloned copy of the gene will enable examination of the relationship, if any, between nanophthalmos and less severe forms of hyperopia and between nanophthalmos and other conditions in which angle-closure glaucoma is a feature.

Hereditary pigmented paravenous chorioretinal atrophy

Pigmented paravenous chorioretinal atrophy (PPCRA) is a rare disorder which is diagnosed primarily because of the typical fundoscopic appearance of retinal pigment epithelial (RPE) atrophy and clumping in a paravenous distribution. A mildly affected and asymptomatic 54-year-old mother and her mildly affected daughter and severely affected son presented with pigmented paravenous chorioretinal atrophy. The severely affected (proband) 28-year-old man manifested the characteristic paravenous chorioretinal atrophy with pigment clusters in both eyes with macular involvement. Besides the characteristic fundus picture, he also had chronic angle closure glaucoma. His 23-year-old sister presented with unilateral involvement. Her right eye showed focal perivenular retinal pigment epithelial hyperplasia at the 2 o'clock position and dilated, tortuous retinal veins, while her left eye had only dilated and tortuous retinal veins. Both patients were hyperopic. Their mother had an area of chorioretinal atrophy in one eye near a retinal vein. The scotopic ERG responses were markedly abnormal in the male patient, while his sister had a mild decrease in amplitude of both a and b waves in both eyes. One of the children of an unaffected family member was found to have dilated and tortuous retinal veins and hyperopia (III-12). To our knowledge, this is the fourth report of familial occurrence of pigmented paravenous chorioretinal atrophy. The present pedigree is compatible with X-linked recessive or dominant inheritance.

[Clinical features and genetic analysis in a family with X-linked incomplete congenital stationary night blindness (CSNBi)]

PURPOSE

We describe particular clinical features in a three-generation family with X-linked CSNBi and present the genetic analysis.

METHOD

The diagnosis of CSNBi was established on clinical and electrophysiological criteria. Polymorphic DNA markers of the Xp region were analyzed by fluorescent polymerase chain reaction.

RESULTS

Clinical findings evidenced an atypical association of both myopia and hyperopia in the same brotherhood. The most interesting feature in this family was the observation of major worsening of the clinical shape between the first and the third generation of affected individuals. DNA analysis did not show significant linkage between the disease and markers of the Xp11-p21 region. Southern analysis did not show expansion of trinucleotide repeat CAG/CTG and CCG/CGG over the three generation.

CONCLUSION

Haplotypic analysis together with clinical observations allow to exclude the existence of a myopia gene closely linked to the CSNB2 locus. The clinical anticipation observed in this family does not seem to be linked with trinucleotide repeat expansion CAG/CTG or CCG/CGG.

Most Jacobsen syndrome deletion breakpoints occur distal to FRA11B

Recent studies have identified a (CCG)n repeat in the 5' untranslated region of the CBL2 protooncogene (11q23.3) and have demonstrated that expansion of this repeat causes expression of the folate-sensitive fragile site FRA11B. It has also been demonstrated that FRA11B is the site of breakage in some cases of Jacobsen syndrome (JS) involving terminal deletions of chromosome 11q. We report on 2 patients with JS and a 46,XX,del(11)(q23.3) karyotype. In both cases, microsatellite and fluorescence in situ hybridization analyses indicated that the deletion breakpoint was approximately 1.5-3 Mb telomeric to FRA11B. There was no evidence of expansion of the CBL2 (CCG)n repeat in the parents of either patient. The deleted chromosome was of paternal origin in both cases, although it was of maternal origin in the cases reported to be caused by FRA11B. These findings and those in previously reported patients suggest that the breakpoint for most 11q deletions in JS patients is telomeric to FRA11B, which raises the possibility that there may be other fragile sites in 11q23.3 in addition to FRA11B. These findings also support previous evidence that there may be a propensity for breakpoints to differ depending on the parental origin of the deleted chromosome.

Ocular abnormalities in a patient with partial deletion of chromosome 6p. A case report

We report on a patient with a de-novo deletion of chromosome 6p. This male infant presented with multiple systemic congenital defects together with an unusual ocular phenotype. Slit-lamp examination revealed thin, opaque, rectilinear bands within the anterior segment partially connecting iris to corneal endothelium. These were associated with bilateral hyperopia and optic nerve hypoplasia. Ocular abnormalities in such patients have been documented although the number of individuals is small and identical cytogenetic defects are rarely encountered. We compare the clinical findings in this case with previously described phenotypes. Characterisation of such cases is important as it is becoming apparent that deletion of genetic information encoded on chromosome 6p has implications for ocular embryogenesis.

The autosomal dominant syndrome with congenital stapes ankylosis, broad thumbs and hyperopia

A family is reported with conductive hearing loss, hyperopia, broad thumbs and broad first toes. The family resembles a previous reported family (Teunissen B, Cremers CWRJ (1990) Laryngoscope 100: 380-384) but additionally all affected members have a typical face. Overlap of the Teunissen and Cremers syndrome with the facio-audio-symphalangism syndrome and proximal symphalangism is discussed.

Deletion of chromosome 21 in a girl with congenital hypothyroidism and mild mental retardation

We report on a girl with a large interstitial deletion of the long arm of chromosome 21 and with mild mental retardation, congenital hypothyroidism, and hyperopia. The deletion [del(21)(q11.1-q22.1)] extends molecularly from marker D21S215 to D21S213. The distal breakpoint is not clearly defined but is situated between markers D21S213 and IFNAR. This patient has the largest deletion of chromosome 21 known without having severe mental retardation or malformations. The deletion does not involve the "Down syndrome chromosome" region, the region of chromosome 21 which in trisomy causes most of the manifestations of Down syndrome. Apparently, the proximal part of the long arm of chromosome 21 does not include genes that are responsible for severe clinical effects in the event of either deletion or duplication, since several reported patients with either trisomy or deletion of this region have mild phenotypic abnormalities. Congenital hypothyroidism is much more common in Down syndrome than in the average population. Thus, the congenital hypothyroidism of the present patient might indicate that there is one or several genes on the proximal part of chromosome 21, which might be of importance for the thyroid function.

Correlations between familial refractive error and children's non-cycloplegic refractions

We examined the spherical equivalent refractions of 237 subjects who had been seen four or more times in a longitudinal study of refractive development in normal children. We employed both photorefraction and autorefraction using a Canon R1 autorefractor. We performed an analysis of variance (F-test for Lack of Fit) to determine the significance of a linear regression in fitting these refractions against three different measures of familial refractive status. One measure included only the number of myopic parents, a second took into account the number of hyperopic parents, and a third included the refractive states of extended genetic relatives. We found no significant correlation between photorefractive data and familial refractions; however, we did find significant, albeit weak, correlations between all measures of familial refractive status and infrared autorefractions of their children. A linear relationship between autorefractive data and overall familial refractive state was found to be most significant. Linear regression of children's autorefractions against a measure of parental myopia and hyperopia was less significant, while a linear model fitting only a measure of parental myopia was least significant, in addition to showing other non-linear trends. We attribute the failure to find a significant correlation between parent and offspring refractions using children's photorefractive data to vignetting by the apparatus and to the short distance of the fixation target. We believe the significant correlation patterns found with the autorefractor reflect the inheritance patterns of parental and familial refractive states.

Aland island eye disease: clinical and electrophysiological studies of a Welsh family

Clinical and molecular genetic studies were performed on a single, large, white family, in which congenital nystagmus and moderate to high refractive error segregated as a sex linked trait with manifestation in some female carriers. In this family, affected males demonstrate myopia, but a high proportion of female carriers, and some of the possibly affected males, show hypermetropia. Clinical ophthalmic examination and electrodiagnostic studies of retinal function were fully compatible with a diagnosis of either incomplete congenital stationary night blindness or of Aland island eye disease. Previous studies have mapped both disorders to the proximal short arm of the X chromosome: our molecular studies support this localisation. Incomplete congenital stationary nightblindness and Aland Island eye disease could be considered as a single entity.

[Video refraction measurement in the first year of life]

BACKGROUND

426 children were examined, using the isotropic photorefraction method (Atkinson et al. 1981). The aim of this study was to analyze whether the frequency of convergent strabismus and/or amblyopia would increase, particularly in cases of high ametropia, and whether the early prescription of spectacles would be beneficial. The preliminary results of this study are presented here.

MATERIALS AND METHODS

426 children aged between 5 and 12 months were examined. Family history, particularly involving strabismus, ametropia and amblyopia, was ascertained and taken into consideration.

RESULTS

Spherical refraction: 92% of the children were emmetropic or slightly hyperopic (< or = +2.5 D). 3.4% were hyperopic (> +2.5 D spherical equivalent) and 4.6% were myopic (0.9 > or = -2.0 D). Astigmatism: 85% had no or mild (< or = 1.5 D) astigmatism. Values greater than 3.5 D were rarely seen. Anisometropia: 67% of the children had no side-difference and only 2.4% had anisometropia with values greater than 1.5 D. Family history/orthoptic findings: 2.6% of the examined population had strabismus. In 12.2% of all the cases one or more first degree relatives had strabismus. Hyperopia and strabismus were found more frequently in this latter group, namely hyperopia (> +2.5 D spherical equivalent) in 13.6% and strabismus in 11.5%.

CONCLUSIONS

Refractive errors greater than 2.5 D were seldom seen in this study, and yet were more frequently detected in families with a history of strabismus. In our opinion, isotropic photorefraction is a method most suitable to screening these especially high-risk groups.

High hyperopia with papillomacular fold

We report a case of evolutive high hyperopia in a child aged 10 years. It is associated with organic amblyopia due to a large papillomacular retinal fold. Ultrasonography and CT scan helped to establish the diagnosis. This is probably a hereditary disease affecting the development of the posterior sclera.

Genetics of epidermal ridges: a study in subjects with refractive errors

The dermatoglyphic characteristics of subjects with refractive errors when compared with control group revealed significant differences in both qualitative and quantitative parameters. The loops were increased in male myopics; the whorls were increased in male hypermetropics and astigmatics and the arches were decreased in all types of refractive errors in males. However, the whorls were decreased in female hypermetropics only. The mean total ridge count was significantly higher in male astigmatics only. As regards pattern intensity (fingers) no significant difference in the mean value was observed in either sex with any type of refractive errors when compared with those of controls.

Early-onset autosomal dominant retinitis pigmentosa with severe hyperopia

We studied a four-generation family with early-onset autosomal dominant retinitis pigmentosa, severe hyperopia, and axial eye lengths of less than 20 mm. The affected members had decreased vision, night blindness, typical peripheral retinal pigmentary changes, and electroretinographic abnormalities characteristic of retinitis pigmentosa. This pedigree suggests there is another variant of retinitis pigmentosa associated with hyperopia besides Leber's congenital amaurosis and preserved para-arteriole retinal pigment epithelium.