Focal polymicrogyria, continuous spike-and-wave discharges during slow-wave sleep and Cohen syndrome: a case report

Cohen syndrome is a rare genetic disorder consisting of truncal obesity, hypotonia, mental retardation, characteristic facial appearance and ocular anomalies. Other diagnostic clinical features include narrow hands and feet, low growth parameters, neutropenia and chorioretinal dystrophy. Here, we report an 18-year-old male with Cohen syndrome associated with focal polymicrogyria and continuous spike-and-wave discharges during slow-wave sleep.

[Familial high myopia--challenge of modern genetics]

In this paper has been accomplished an estimation of contemporary achievement in molecular researches domain's of pathology in familial high myopia. Clinical observations of monozygotic and dizygotic twins groups and also among family members with this type of myopia disclosing in following generations show, that it has inborn character. Nowadays, it has been identified three gen locci connected with heritage of this illness unit: 18p11.31, 12q21-31, 7q36. Above incontestable achievements do not interpret mechanism uprising this disease. Problem is still, to define the products planned by exchanged area of DNA, conditioning progress of high familial myopia.

Clinical description and exclusion of candidate genes in a novel autosomal recessively inherited vitreoretinal dystrophy

OBJECTIVES

To describe the clinical phenotype of a novel autosomal recessively inherited vitreoretinal dystrophy in one generation of a family originating from eastern Switzerland.

METHODS

A clinical study including electroretinographic investigations followed by laboratory-based genetic and molecular analysis. Four affected and 3 unaffected members of the family were examined. Ten candidate regions were tested by linkage analysis with highly polymorphic molecular markers or with intragenic restriction fragment length polymorphisms.

RESULTS

Of 8 siblings,4 were affected, showing high myopia with pronounced vitreous liquefaction, retinitis pigmentosa-like retinal degeneration, diffuse retinal pigment epithelium atrophy, macular staphylomata, and premature cataract formation. Strikingly abnormal results on electroretinograms, affecting both the rod and the cone systems, revealed an extensive defect of retinal function, unlike those usually found in pathologic myopia. No extraocular manifestations were observed. Three types of nonsyndromic high myopia, Stickler syndrome I, II, and III, Wagner syndrome, Knobloch syndrome, Goldmann-Favre dystrophy, and multiple vitreoretinopathies were excluded by linkage analysis.

CONCLUSIONS

The reported phenotype as well as the results of molecular linkage analysis in the siblings described here suggest an autosomal recessively inherited vitreoretinal dystrophy, which, to our knowledge, has not been described until now.

Ophthalmic manifestations of congenital disorder of glycosylation type 1a

PURPOSE

To present the ophthalmic manifestations of patients with congenital disorder of glycosylation type Ia (CDG-Ia) due to the frequent R141H/F119L PMM2 genotype.

METHODS

Ophthalmic records of 23 patients (age: 10 months to 20 years) were evaluated. They had had at least one ophthalmic reexamination.

RESULTS

Measurements of refractive error showed that 18 patients were myopic, two were hypermetropic, and three could not be measured. Serial measurements in 12 patients indicated a progression towards myopia of 0.80 diopters (D) per year. Congenital esotropia and delayed visual maturation (DVM) were consistent findings. Two children developed good visual acuity (VA), 16 had low vision, and five were legally blind. Pallor of the optic disc was noted in five patients. Electroretinography (ERG) performed in nine patients showed reduced rod responses, while cone responses were only slightly reduced.

CONCLUSIONS

The present study illustrates the difficulties in examining severely disabled children. Consistent ophthalmic manifestations of CDG-Ia patients due to the R141H/F119L genotype were congenital esotropia, DVM, and a reduced rod response in ERG-examined patients. The vast majority of patients had reduced VA and developed myopia. We speculate that there is a relationship between the glycosylation defect in CDG-Ia and the development of myopia. We recommend that CDG-Ia patients be followed annually by an ophthalmologist.

Ocular and scleral alterations in gene-targeted lumican-fibromodulin double-null mice

PURPOSE

To elucidate the role of leucine-rich proteoglycans lumican and fibromodulin in the sclera.

METHODS

Lumican- and fibromodulin-null heterozygous mice were intercrossed to obtain wild-type (Lum(+/+)Fmod(+/+)), lumican-null (Lum(-/-)Fmod(+/+)), fibromodulin-null (Lum(+/+)Fmod(-/-)), and double-null (Lum(-/-)Fmod(-/-)) littermates. Axial length was measured on enucleated whole eyes, and ocular structural changes were examined by histology. The morphology of collagen fibrils in the sclera was examined by transmission electron microscopy (TEM).

RESULTS

Compared with the ocular axial length in wild type mice, the axial length was increased by 10% in Lum(-/-)Fmod(-/-) (P = 0.02) mice. Retinal detachment was frequent in the double-null and rare in the lumican-null animals. Compared with the wild-type sclera, the sclera in all null mutants was significantly thinner with fewer lamellae (P < 0.05). The double-null sclera contained abnormally large-diameter (120-160 nm) and small-diameter (30-60 nm) collagen fibrils, whereas the fibromodulin-null sclera was enriched for the small-diameter fibrils. The collagen fibril diameter distribution in the lumican-null sclera was similar to that of the wild-type.

CONCLUSIONS

An increase in small-diameter fibrils in the fibromodulin-null sclera suggests a key role for fibromodulin in the maturation and assembly of scleral collagen fibrils. That fibril diameter distribution in the lumican-null sclera was comparable to that in the wild type, but severely disrupted in the double null, suggests a role for lumican that is crucial in the absence of fibromodulin. The eyes of Lum(-/-)Fmod(-/-) mice show certain features of high myopia: increased axial length, thin sclera, and retinal detachment. Mutations or altered expression of these proteoglycans may contribute to myopia in humans.

Collagen gene expression and the altered accumulation of scleral collagen during the development of high myopia

The development of high myopia is associated with reduced scleral collagen accumulation, scleral thinning, and loss of scleral tissue, in both humans and animal models. Reduced collagen fibril diameter is also observed in the sclera of eyes with high myopia. The present study investigated aspects of scleral collagen synthesis and degradation, in a mammalian model of high myopia, to elucidate the factors underlying scleral changes. General synthesis and degradation of scleral collagen was investigated in monocularly deprived tree shrews, through the in vivo administration of [(3)H]proline and subsequent assay of scleral tissue for [(3)H]collagen. In addition, PCR enriched cDNA, produced from tree shrew scleral mRNA, was used to synthesize probes for hybridization to custom gene arrays consisting of partial sequences for 11 collagen subtypes. Finally, real-time reverse transcriptase-PCR was employed to investigate collagen type I, III, and V mRNA expression in the sclera of myopic, contralateral control, and normal tree shrew eyes. Scleral [(3)H]proline incorporation was reduced at the posterior pole of myopic eyes following 5 days of monocular deprivation (-36 +/- 4%), whereas [(3)H]proline content was similar in treated and control eyes before myopia induction (-1 +/- 8%) but was reduced in myopic eyes following 5 (-8 +/- 2%), 12 (-15 +/- 4%), and 24 (-10 +/- 4%) days of myopia induction. The majority of the collagens investigated were found to be expressed in the sclera, with 11 subtypes being identified. Collagen type I mRNA expression was reduced in the sclera of myopic eyes (-20 +/- 7%), however, collagen type III (+2 +/- 9%) and type V (-1 +/- 6%) expression was unchanged relative to control, resulting in a net increase in the ratio of expression of collagen type III/type I and collagen type V/type I (22 and 25%, respectively). These results show that reduced scleral collagen accumulation in myopic eyes is a result of both decreased collagen synthesis and accelerated collagen degradation. Furthermore, changes in collagen synthesis are driven by reduced type I collagen production. Short term increases in the ratio of newly synthesized collagen type III/type I and type V/type I are likely to be important in the increasing frequency of small diameter scleral collagen fibrils observed in high myopia and may be important in the subsequent development of posterior staphyloma in humans with pathological myopia.

Ocular manifestations of Donohue's syndrome

INTRODUCTION

Donohue's syndrome, also known as Leprechaunism, is a rare autosomal recessive disease that manifests at birth with symptoms of endocrine dysfunction. Metabolic characteristics of the disease include postprandial hyperglycemia, fasting hypoglycemia, insulin resistance, hyperinsulinemia, and failure to thrive. The physical features most often associated with this condition include hypertrichosis, pachyderma, acanthosis nigricans, prominent genitalia, and elfin-like facial characteristics of prominent eyes, wide nostrils, thick lips, and large, low-set ears. Not only is this syndrome rare, but it often results in infant and early childhood mortality. The literature regarding ocular manifestations is limited.

CASE REPORT

We present a case of a 29-year-old male with Donohue's syndrome and significant ocular findings including a subluxated mature cataract, retinal detachment, high myopia, and optic atrophy.

DISCUSSION

These ocular sequelae are discussed with regard to the noted endocrine dysfunction and its effects on tissue development and growth.

New locus for autosomal dominant high myopia maps to the long arm of chromosome 17

PURPOSE

To map the gene(s) associated with autosomal dominant (AD) high-grade myopia.

METHODS

A multigeneration English/Canadian family with AD severe myopia was ascertained. Myopes were healthy, with no clinical evidence of syndromic disease, anterior segment abnormalities, or glaucoma. The family contained 22 participating members (12 affected). The average age of diagnosis of myopia was 8.9 years (range, birth to 11 years). The average refractive error for affected adults was -13.925 D (range, -5.50 to -50.00). Microsatellite markers for genotyping were used to assess linkage to several candidate loci, including three previously identified AD high-myopia loci on 18p11.31, 12q22-q23, and 7q36. Syndromic myopia linkage was excluded by using intragenic or flanking markers for Stickler syndrome types 1, 2, and 2B; Marfan syndrome; Ehlers-Danlos syndrome type 4; and juvenile glaucoma. A full genome screening was performed, with 327 microsatellite markers spaced by 5 to 10 cM. Two-point linkage was analyzed using the FASTLINK program run at 90% penetrance and a myopia gene frequency of 0.0133.

RESULTS

Linkage to all candidate loci was excluded. The genome screening yielded a maximum two-point lod score of 3.17 at theta = 0 with microsatellite marker D17S1604. Fine mapping and haplotype analysis defined the critical interval of 7.71 cM at 17q21-22.

CONCLUSIONS

A novel putative disease locus for AD high-grade myopia has been identified and provides additional support for genetic heterogeneity for this disorder.

Myopia, genetics, and ambient lighting at night in a UK sample

BACKGROUND

It has been reported that exposure to artificial lighting at night during the first 2 years of life was very strongly associated with subsequent myopia development.

METHODS

The strength of this association was tested in a UK sample for the first time. The study population comprised 122 university students.

RESULTS

Myopia occurred with approximately equal frequency in those who slept with and without light exposure at night. In contrast, two largely genetic factors, parental myopia and race, were both significantly associated with myopia development, as has been found previously.

CONCLUSION

This study provides further support for the view that night-time light exposure during infancy is not a major risk factor for myopia development in most population groups. In a subset of this cohort for which spectacle prescriptions were available for both parents (49 trios), the heritability of ocular refraction was estimated to be 0.31.

What all nurses need to know about Stickler syndrome

Stickler syndrome is one of the most common clinical syndromes in Europe although it is also one of the least known and consequently most misidentified. Because Stickler syndrome affects connective tissue, many different symptoms present, from vision to mobility difficulties. This article examines the main symptoms of the syndrome and includes an insightful personal account showing how it affects the whole family.

Familial high myopia linkage to chromosome 18p

A locus for autosomal dominant high myopia was reported on chromosome 18p. We sought to confirm this finding and narrow the reported interval by analyzing high myopia among families of Hong Kong Chinese, in whom myopia is common. In 15 families with a possibly autosomal dominant inheritance of high myopia (>or=-6 dpt) in at least 2 generations, 10 chromosome 18p markers were analyzed for linkage with high myopia. Two-point linkage analysis showed trends toward linkage of markers D18S476 and D18S62 with high myopia, with maximum logarithm of odds (LOD) scores of at least 1.1 and 1.7, respectively. Multipoint analysis of those 2 markers gave a maximum LOD score of at least 2.1. To attempt to account for likely genetic heterogeneity, 5 families showing evidence of linkage of the 2 markers with high myopia were selected for further multipoint linkage analysis, resulting in a maximum LOD score of 2.4 at D18S476. While multiple genetic and environmental factors likely contribute to myopia, these data are consistent with the possibility of a locus on chromosome 18p.

TGFbeta-induced factor: a candidate gene for high myopia

PURPOSE

To investigate the coding exons of transforming growth factor (TGF)-beta-induced factor (TGIF) for mutations in Chinese patients with high myopia.

METHODS

Seventy-one individuals with high myopia of -6.00 D or less and 105 control subjects were screened by DNA sequencing for sequence alterations. Univariate analysis and logistic regression were performed to identify single-nucleotide polymorphisms (SNPs) and their interactions in TGIF that may be associated with myopia.

RESULTS

Six SNPs showed a significant difference (P < 0.05) between patient and control subject in univariate analysis. Four of them cause codon changes: G223R, G231S, P241T, and A262G. Among all the SNPs that entered multivariate analysis, only 657(T-->G) showed statistical significance in the logistic regression model (odds ratio 0.133; 95% confidence interval 0.037-0.488; P = 0.002).

CONCLUSIONS

TGIF is a probable candidate gene for high myopia. Further studies are needed to identify the underlying mechanism.

Parental myopia, near work, school achievement, and children's refractive error

PURPOSE

To quantify the degree of association between juvenile myopia and parental myopia, near work, and school achievement.

METHODS

Refractive error, parental refractive status, current level of near activities (assumed working distance-weighted hours per week spent studying, reading for pleasure, watching television, playing video games or working on the computer), hours per week spent playing sports, and level of school achievement (scores on the Iowa Tests of Basic Skills [ITBS]) were assessed in 366 eighth grade children who participated in the Orinda Longitudinal Study of Myopia in 1991 to 1996.

RESULTS

Children with myopia were more likely to have parents with myopia; to spend significantly more time studying, more time reading, and less time playing sports; and to score higher on the ITBS Reading and Total Language subtests than emmetropic children (chi(2) and Wilcoxon rank-sum tests; P < 0.024). Multivariate logistic regression models showed no substantial confounding effects between parental myopia, near work, sports activity, and school achievement, suggesting that each factor has an independent association with myopia. The multivariate odds ratio (95% confidence interval) for two compared with no parents with myopia was 6.40 (2.17-18.87) and was 1.020 (1.008-1.032) for each diopter-hour per week of near work. Interactions between parental myopia and near work were not significant (P = 0.67), indicating no increase in the risk associated with near work with an increasing number of parents with myopia.

CONCLUSIONS

Heredity was the most important factor associated with juvenile myopia, with smaller independent contributions from more near work, higher school achievement, and less time in sports activity. There was no evidence that children inherit a myopigenic environment or a susceptibility to the effects of near work from their parents.

[Polyarthritic manifestations revealing Stickler syndrome]

Stickler syndrome, also called hereditary arthro-ophthalmopathy is a dominant disorder, with poly-epiphyseal dysplasia resulting in early osteoarthritis. It usually includes bilateral myopia, that changes little during the follow up period, but can lead to retinal detachment. Children with Stickler syndrome can show facial dysmorphism that may improve with age, but severe anomalies may exist such as Pierre Robin sequence. Our case, a woman, 20-year-old, presents chronic polyarthritis which is an unusual feature of this disease. The diagnosis of Stickler's syndrome is based on polyepiphyseal dysplasia in skeletal radiography and bilateral myopia. Otherwise, this patient has no facial dysmorphism.

Similar genetic susceptibility to form-deprivation myopia in three strains of chicken

Myopia development in humans depends on a complex interplay between genetic and environmental factors. Many of those who become myopic when exposed to a myopigenic environment are likely to do so because of a genetic susceptibility, whereas others somehow remain immune. In the most intensively studied model of environmentally induced myopia, form-deprivation myopia in the chick, there is convincing evidence of differential genetic susceptibility to myopia development, both within-strains and between-strains. To date, however, these have involved relatively small differential responses. The aim of this investigation was to examine genetic susceptibility to a highly uniform regimen of form-deprivation in three strains of chick (white leghorn, brown leghorn and broiler) expected to differ greatly in genetic background and in normal eye size, and to gauge the potential for mapping the quantitative trait loci (QTL) underlying this differential susceptibility. Despite striking differences in normal eye size, all three strains studied developed a similar degree of induced myopia. Whilst the degree of induced vitreous chamber elongation differed significantly between-strains, it was concluded that the high within-strain variation in the response to form-deprivation would prevent the effective application of QTL mapping approaches to identify genes conferring this susceptibility. In contrast, the strains used here would be ideal for use in mapping QTL controlling normal ocular component dimensions.

Genetic loci for pathological myopia are not associated with juvenile myopia

The purpose of this study was to evaluate chromosomal regions previously linked to pathological myopia for linkage to juvenile myopia in a sample of myopic children and their families. Of 125 families with a myopic child participating in the Orinda longitudinal study of myopia, 53 submitted 221 buccal swab samples for genetic analysis. Myopia in proband children was defined as -0.75 D or more myopia in both meridians on cycloplegic autorefraction (1% tropicamide). Affected status in parents and siblings was obtained by survey. DNA was extracted from buccal mucosal cells, amplified by polymerase chain reaction (PCR), and then analyzed with seven markers for chromosome 12 and five markers for chromosome 18 in the regions previously associated with pathological myopia. LOD scores were not significant for any marker tested. The largest positive LOD score was 0.15 for GATA30F04. Model-free methods using a SimIBD approach suggested a possible linkage at one marker, GATA6H09 (P = 0.003), but these results were not supported by transmission disequilibrium test (TDT) analysis. The statistical power to detect LOD scores of > or =1.0, assuming homogeneity, was estimated at 93.2%. We found no confirmatory evidence of linkage between juvenile myopia and regions of chromosomes 12 and 18 previously associated with pathological myopia.

Phenotypic expression of the complete type of X-linked congenital stationary night blindness in patients with different mutations in the NYX gene

PURPOSE

To describe the clinical phenotype of the complete type of X-linked congenital stationary night blindness (CSNB1) with different types of mutations in the NYX gene.

METHODS

The clinical and genetic data from 18 male patients with eight different mutations from two ophthalmological institutes were reviewed. The variability in refractive error, reduced visual acuity and full-field electroretinogram (ERG) recordings was examined.

RESULTS

Parameters were quantitatively analyzed based on the classification of mutations according to their predicted effect on protein structure and function. CSNB1 patients with mutations changing structurally conserved residues ( n=12) tended to have a lower degree of myopia than patients with mutations of non-conserved residues ( n=6). Visual acuity loss and the 30 Hz flicker ERG recordings were similar in the two groups. Values for the b/a amplitude ratio tended to be clustered in patients carrying the same mutation. Refractive error and the b/a amplitude ratio were highly correlated between the two eyes of an individual.

CONCLUSIONS

These data suggest correlations between phenotypic expression in CSNB1 and individual genotypes as well as class types of mutations based on the extent of structural amino acid conservation. A high inter-eye correlation suggests that other genetic or environmental factors, rather than chance, play a part in determining the phenotypic diversity in CSNB1.

An Italian family affected by autosomal dominant microcephaly with chorioretinal degeneration

PURPOSE

We studied an Italian family affected by the autosomal dominant form of microcephaly and chorioretinal degeneration that was characterized by various degrees of clinical expression.

METHODS

An ophthalmologic examination, including visual acuity, visual field testing, an electroretinogram, and fundus photography, and a neurologic examination, including neurodevelopmental status and neuroimaging studies, were performed for all subjects. Skeletal radiography, chromosome studies, and serologic investigations were also performed.

RESULTS

In this family, only two of the six affected members had an association of microcephaly, myopia, and chorioretinal degeneration. The other family members showed microcephaly, slight mental retardation, and short stature, but not chorioretinopathy.

CONCLUSIONS

The significant finding in members from this dominant pedigree of microcephaly was the association of short stature and high myopia, heretofore seen only in families with recessive microcephaly. These findings could be useful for genetic counseling in the apparently isolated forms of microcephaly with chorioretinopathy.

Choroidal neovascularization occurring concurrently in myopic eyes of monozygotic twins

PURPOSE

To present young monozygotic twins both of whom developed choroidal neovascularization at the same time.

CASE/OBSERVATIONS

Monozygotic twins, 22-year-old women, who lived in the same house, developed choroidal neovascularization in the left eye at the same time. The degree of myopia was higher in the left eye (-7.75 and -8.5 dpt in spherical equivalent) than in the right eye (-6.75 and -4.5 dpt) of both patients. The choroidal neovascularization regressed in a different time course and the visual acuity returned to normal in both patients.

CONCLUSION

This pair of monozygotic twins suggests that both genetic and environmental factors underlie the development of choroidal neovascularization in myopic eyes.

High heritability of myopia does not preclude rapid changes in prevalence

The aetiology of myopia is complex, but the major form of myopia results from an interplay between genetic factors and environmental influences. Although there are clear patterns of family inheritance and high heritability values in studies from all over the world,environmental factors are increasingly important in determining myopic outcomes in East Asia, and perhaps elsewhere. This is not paradoxical, as high heritability does not preclude strong environmental influences. The lower heritability values obtained from parent-offspring correlations in populations of East Asian origin where there are marked differences in the environmental exposures (education and urbanization) of parents and children, and where there has been a major shift in the population distribution of myopia, are consistent with this view. Despite the impact of environmental pressures in East Asia, there is evidence that parental myopia influences the position of their offspring within that new population distribution.

Myopia and models and mechanisms of refractive error control

Myopia represents a failure of the normal process of emmetropization, which is essentially endogenous to the eye. Emmetropization involves defocus detection at the level of the amacrine and bipolar cells of the outer retina, diffusion of a signal or signals across the retinal pigment epithelium and choroid, and alteration of the scleral matrix, likely through modulation of proteoglycan synthesis. Elucidating and effectively bolstering the deficient steps in this regulatory pathway would mark a significant advance given myopia's tremendous impact. Clinical experience, longitudinal studies, epidemiological data and numerous animal experiments have enhanced our understanding of myopia. Interpretation of the epidemiological data is often complicated by the difficulties of distinguishing environmental from genetic influences, especially those pertaining to slow developmental changes. Likewise, it is important that the animal models be interpreted with an appreciation that the human eye varies structurally and developmentally from that of other species. Studies of the chick eye have formed the basis for several hypotheses of myopic development, but the chick does not possess a fovea or retinal blood supply. It is unclear whether these differences alter the pathways of emmetropization. Even closely related primate species can exhibit different responses to form deprivation conditions, suggesting differing mechanisms of eye growth control. Monocular occlusion of the rhesus macaque, for instance, results in myopia when the ciliary muscle is paralyzed or the optic nerve cut, but does not in the stumptailed macaque, suggesting a role of excessive accommodation in the development of myopia in the stumptail but not the rhesus [36]. Given such variability in the models a persisting element of continued myopia research must be an evaluation of the relevance of any given model to the human condition. In this regard, the study of changing patterns of gene expression within and among species during emmetropization and myopic progression may offer a productive avenue for future research.

A novel approach to search for identity by descent in small samples of patients and controls from the same mendelian breeding unit: a pilot study on myopia

Autosomal dominant high myopia, a genetic disorder already mapped to region 18p11.31, is common in Carloforte (Sardinia, Italy), an isolated village of 8,000 inhabitants descending from a founder group of 300 in the early 1700s. Fifteen myopic propositi and 36 normal controls were selected for not having ancestors in common at least up to the grandparental generation, although still descendants of the original founders. All subjects were genotyped for 14 markers located on autosome 18 at a resolution of about 10 cM. Allelic distributions were found to be similar at all tested loci in propositi and controls, except for the candidate marker D18S63 known to segregate in close linkage association with high myopia. In particular, the frequency of allele 85 among the propositi was almost double that of the controls (Fisher's exact test, p = 0.037). The association is more striking when the frequency of the genotype 85/85 in the two groups is compared (Fisher's exact test, p = 0.005). This conclusion was further evaluated through a bootstrap analysis by computing the overall probability of the observed data under the null hypothesis (i.e. no difference between the two groups in frequency distributions for the chromosome 18 markers). Again, marker D18S63 was found to have a sample probability lower than 0.004, which is significant at the 0.05 level after correcting for simultaneous testing of multiple loci. The study demonstrates the efficiency of our novel strategy to detect identity by descent (IBD) in small numbers of patients and controls when they are both part of well-defined Mendelian breeding units (MBUs). The iterative application of our strategy in separate MBUs is expected to become the method of choice to evaluate the ever-growing number of reported associations between candidate genes and multifactorial traits and diseases.