Central areolar pigment epithelial dystrophy

A large population study reveals a novel association between congenital color vision deficiency and environmental factors

PURPOSE

To assess the associations between the prevalence of congenital color vision deficiency (CVD) and genetics and environment, represented by place of origin (ethnic background) and place of birth, respectively.

METHODS

This is a retrospective study of the computerized database of the northern recruitment center of Israel of 53,895 consecutive male Jewish conscripts 16-19 years old, who completed the medical profiling process between 1988 and 2011. CVD was diagnosed using the 24-pseudo-isochromatic plate Ishihara test. Associations of CVD prevalence with sociodemographic variables, anthropometric indices, refractive errors, and mainly place of origin and place of birth were tested by both univariate analysis and multivariate regression models.

RESULTS

Elevated BMI (obesity) and blood pressure (hypertension), as well as myopia, were all positively associated with congenital CVD. The composition of the study population provides a unique opportunity to investigate the relationship between ethnicity and environment. The prevalence of CVD significantly differs among subpopulations of different ethnic background as well as among those who were born in different geographical locations. Additionally, differences in the prevalence of CVD (1.2-1.6%) were observed among conscripts from the same origin, who were born in Israel, compared to those who were born elsewhere. Both place of origin (p < 0.01) and place of birth (p < 0.05) were associated with the prevalence of CVD in a multivariable regression model.

CONCLUSION

This study affirms previously established associations of CVD with certain variables and reveals a possible novel association of CVD with environmental factors.

North Carolina Macular Dystrophy Is Caused by Dysregulation of the Retinal Transcription Factor PRDM13

PURPOSE

To identify specific mutations causing North Carolina macular dystrophy (NCMD).

DESIGN

Whole-genome sequencing coupled with reverse transcription polymerase chain reaction (RT-PCR) analysis of gene expression in human retinal cells.

PARTICIPANTS

A total of 141 members of 12 families with NCMD and 261 unrelated control individuals.

METHODS

Genome sequencing was performed on 8 affected individuals from 3 families affected with chromosome 6-linked NCMD (MCDR1) and 2 individuals affected with chromosome 5-linked NCMD (MCDR3). Variants observed in the MCDR1 locus with frequencies <1% in published databases were confirmed using Sanger sequencing. Confirmed variants absent from all published databases were sought in 8 additional MCDR1 families and 261 controls. The RT-PCR analysis of selected genes was performed in stem cell-derived human retinal cells.

MAIN OUTCOME MEASURES

Co-segregation of rare genetic variants with disease phenotype.

RESULTS

Five sequenced individuals with MCDR1-linked NCMD shared a haplotype of 14 rare variants spanning 1 Mb of the disease-causing allele. One of these variants (V1) was absent from all published databases and all 261 controls, but was found in 5 additional NCMD kindreds. This variant lies in a DNase 1 hypersensitivity site (DHS) upstream of both the PRDM13 and CCNC genes. Sanger sequencing of 1 kb centered on V1 was performed in the remaining 4 NCMD probands, and 2 additional novel single nucleotide variants (V2 in 3 families and V3 in 1 family) were identified in the DHS within 134 bp of the location of V1. A complete duplication of the PRDM13 gene was also discovered in a single family (V4). The RT-PCR analysis of PRDM13 expression in developing retinal cells revealed marked developmental regulation. Next-generation sequencing of 2 individuals with MCDR3-linked NCMD revealed a 900-kb duplication that included the entire IRX1 gene (V5). The 5 mutations V1 to V5 segregated perfectly in the 102 affected and 39 unaffected members of the 12 NCMD families.

CONCLUSIONS

We identified 5 rare mutations, each capable of arresting human macular development. Four of these strongly implicate the involvement of PRDM13 in macular development, whereas the pathophysiologic mechanism of the fifth remains unknown but may involve the developmental dysregulation of IRX1.

Genotype-phenotype correlations and differential diagnosis in autosomal dominant macular disease

In the past few years, great progress has been made in the understanding of macular diseases. A number of disease-causing genes have been cloned, and numerous loci for other conditions have been mapped. The purpose of this article is to provide an overview of the current understanding of the genotype-phenotype correlations in autosomal dominant macular diseases with an emphasis on differential diagnostic issues. Whenever possible, the molecular correlates have been reviewed and the implications for age-related macular degeneration have been discussed. The many similarities of these diseases to age-related macular degeneration of the atrophic or exudative type, which can be misleading in elderly subjects, have also been addressed. While some conditions yield disease truly confined to the macula, others show widespread retinal involvement on functional testing. Clear-cut genotype-phenotype correlations are possible only for some forms of macular diseases. To further complicate the diagnostic process, there is a considerable degree of clinical overlap between many of them, making the differential diagnostic process potentially challenging. Functional testing, careful assessment of family history and extensive family work-up are essential in differentiating at the clinical level most, but not all, of these disease entities. Awareness of all of these conditions is required to direct correctly diagnostic investigations, to formulate an accurate prognosis, and for proper genetic counseling.

Congenital-onset central chorioretinal dystrophy associated with high myopia

We describe six siblings of a 12-member sibship affected with a macular dystrophy that is congenital in onset and is associated with progressive myopia. The age of these siblings ranged from 7 months to 19 years. The presenting feature was visual impairment and the best corrected visual acuity ranged between 1/60 and 6/36. Myopia ranged from -3.00 dioptres in the youngest to -10.50 dioptres in the second-eldest member. The macular lesions in our patients are characterised by a well-defined area of atrophy of choriocapillaris and retinal pigment epithelium. These lesions progressed with age in both size and depth. The extent of choroidal involvement in the lesions varied from only loss of superficial vasculature to sparing of large choroidal vessels as confirmed by fundus fluorescein angiography. One patient also exhibited bilateral Duane's syndrome (type III) and right unilateral ptosis. To the best of our knowledge such a fully established macular lesion presenting at the age of 6 months and associated with progressive myopia has never been described in literature.

A North Carolina macular dystrophy phenotype in a Belizean family maps to the MCDR1 locus

PURPOSE

To describe the clinical findings of an autosomal dominant macular dystrophy in a family of Mayan Indian ancestry in Belize, Central America, and to determine its molecular genetic relationship with the original North Carolinian family.

METHODS

We performed comprehensive ophthalmic examinations on 56 members of a single family living in Chicago, Illinois, and Belize, Central America. Fundus photography and fluorescein angiography were performed on 17 affected subjects and six affected family members were serially examined over a 12-year period. Blood was collected from 26 individuals, and DNA was extracted for genotyping. Two-point linkage, multipoint linkage, and haplotype analysis was performed.

RESULTS

In 17 affected individuals, the clinical features were consistent with the diagnosis of North Carolina macular dystrophy. Multipoint linkage analysis generated a peak lod score of 5.6 in the MCDR1 region. The haplotype associated with the disease was, however, different from that of the original North Carolinian family.

CONCLUSIONS

This family has an autosomal dominant macular dystrophy that is clinically indistinguishable from North Carolina macular dystrophy (MCDR1). Our findings indicate that the mutated gene in this Belizean family maps precisely to the same region as that of the North Carolina macular dystrophy (MCDR1) locus. This study provides evidence that MCDR1 occurs in various ethnic groups and that there is no evidence of genetic heterogeneity.

An ancestral core haplotype defines the critical region harbouring the North Carolina macular dystrophy gene (MCDR1)

Autosomal dominant North Carolina macular dystrophy (NCMD) or central areolar pigment epithelial dystrophy (CAPED) is an allelic disorder that maps to an approximately 7.2 cM interval between DNA markers at D6S424 and D6S1671 on 6q14-q16.2. The further refinement of the disease locus has been hindered by the lack of additional recombination events involving the critical region. In this study, we have identified three multigeneration families of German descent who express the NCMD phenotype. Genotyping was carried out with a series of markers spanning approximately 53 cM around the NCMD locus, MCDR1. Genetic linkage between the markers and the disease phenotype in each of the families could be shown. Disease associated haplotypes were constructed and provide evidence for an ancestral founder for the German NCMD families. This haplotype analysis suggests that a 4.0 cM interval flanked by markers at D6S249 and D6S475 harbours the gene causing NCMD, facilitating further positional cloning approaches.

The variable expressivity of a family with central areolar pigment epithelial dystrophy

PURPOSE

To clarify the nosology of autosomal dominant central areolar pigment epithelial dystrophy (CAPED) as previously described.

METHODS

The authors studied a family of 69 members spanning six generations with a macular dystrophy. Thirty-four patients were examined, and those found to be affected underwent further testing, including visual fields, electrophysiologic studies, and fluorescein angiography. Family history and medical records were used in three additional deceased patients.

RESULTS

Eleven patients were identified as having CAPED. The phenotype was inherited in an autosomal dominant fashion. Six of these patients were examined by us and had mid-life onset (at 32-53 years) of progressive visual loss (20/50--counting fingers), occurring over a 3- to 10-year period. These subjects had circumscribed hypopigmented maculae, retinal pigment epithelial window defects on fluorescein angiography, central scotomas, and electrophysiologic studies, ranging from normal to severely abnormal. Three deceased patients were presumed to have CAPED by review of records or family history. Two additional patients examined had mild macular changes but good visual acuity and no significant abnormalities on electrophysiologic studies. The latter two patients are presumed to have had early manifestations of CAPED.

CONCLUSION

This family demonstrates that CAPED is an autosomal-dominant hereditary macular dystrophy which has late-onset and variable expressivity.

Full-field electroretinograms in patients with central areolar choroidal dystrophy

Patients with central areolar choroidal dystrophy are often difficult to diagnose because they are similar in fundus appearance to other retinal disorders. Nineteen patients with the diagnosis were studied in order to estimate the diagnostic and prognostic value of full-field electroretinography in this disorder. Our results showed that the cone b-wave amplitude in the ERG is decreased, that there is a progression in this decrease during a follow-up period of 5 years, and that the cone b-wave implicit time is prolonged. Central areolar choroidal dystrophy is considered to be primarily a choroidal disease. Our results indicate that it also affects most or all of the retinal cones. Further, our observations suggest that the disease is slowly progressive and that full-field electroretinography is of value in its early diagnosis.

North Carolina macular dystrophy (MCDR1). A review and refined mapping to 6q14-q16.2

The macular degenerations comprise a heterogeneous group of diseases, generally reported in small families. Single, large family studies of North Carolina macular dystrophy have aided in defining the spectrum of the phenotype of this disorder and its relationship to other macular degenerations. North Carolina macular dystrophy has many phenotypic similarities to age-related macular degeneration with the glaring exception of the early age of onset of North Carolina macular dystrophy. The authors initially reported mapping this disease by linkage to the long arm of chromosome 6. They now report additional data on a total of 247 individuals in the original North Carolina macular dystrophy family whom we ascertained for clinical and molecular genetic studies. Standard clinical ophthalmic examination revealed that 96 of these individuals were affected. Molecular genetic studies increased the LOD score to 23 and refined the genomic localization of the disease-causing gene to 6q14-q16.2.

North Carolina macular dystrophy is assigned to chromosome 6

North Carolina macular dystrophy (NCMD) is an autosomal dominant macular dystrophy causing impaired central vision at an early age, is completely penetrant, and is present in a single large family. With the development of the hypervariable microsatellite (CA repeats) markers in the human genome, it was possible to relatively rapidly screen most of the genome for linkage to the NCMD gene. After utilizing 124 genetic markers, which excluded over 95% of the human genome, three Marshfield microsatellites located at 6q13-q21 were linked to the NCMD locus. Marshfield marker (MFD) 131 gave a lod score of Z(theta) = 4.36 at theta = 0.137; MFD 171 gave a Z(theta) = 8.42 at theta = 0.004; and MFD 97 gave a Z(theta) = 13.10 at theta = 0.017. Other retinal diseases have been reported on 6q stressing the importance of this region and possibly suggesting that these diseases may be allelic or located in part of a large macular gene family. Locating and characterizing the NCMD gene may be an important step in understanding this group of maculopathies as well as age-related macular degeneration (AMD), a common cause of blindness in the elderly.

North Carolina macular dystrophy: exclusion map using RFLPs and microsatellites

The autosomal dominant macular dystrophies are a confusing group of poorly understood diseases. Linkage studies will greatly aid our classification of these disorders and hopefully provide insight into central retinal function and dysfunction such as occurs in age-related macular degeneration. North Carolina macular dystrophy is one such disease that has been amenable to linkage analysis because of the large pedigree size. Seventy-six polymorphic markers have been tested for linkage and exclusion data are presented.

North Carolina's dominant progressive foveal dystrophy: how progressive is it?

We studied 34 family members at risk of having dominant progressive foveal dystrophy of Lefler, Wadsworth, and Sidbury (also called North Carolina macular dystrophy) and found 17 to be affected. Fifteen of these affected subjects were observed over at least a 10-year period for evidence of progressive macular degeneration. Only one subject showed objective evidence of progressive deterioration in only one eye. Our findings further substantiate that this dystrophy generally has a stable course, contrary to its original description.

Early findings in central areolar choroidal dystrophy

We examined 69 members of two caucasian families with an autosomal dominant form of central areolar choroidal dystrophy using ophthalmoscopy and fundus photography. In five members who had a good visual acuity macular lesions were found. In three of them retinal function tests were performed, which turned out to be normal. These 5 patients underwent fluorescein angiography. Early symptoms of central areolar choroidal dystrophy are small parafoveal hyperfluorescent areas due to retinal pigmentepithelium loss and areas of pigment mottling in the macula. Until now the early lesions of central areolar choroidal dystrophy in patients with a good visual acuity in both eyes have not been described clearly.

North Carolina macular dystrophy, revisited

Progression of the maculopathy in North Carolina macular dystrophy (NCMD) was not well documented. Thus, the author recently examined 22 affected members of the original kindred. Evidence of progression of the macular disease was sought through comparison of the recent fundus findings with old fundus photographs and from subjective complaints of worsening visual acuity. Only 1 of the 22 affected subjects had evidence of such change. Additionally, two new findings of NCMD were observed: (1) severe macular lesions which were staphylomatous or excavated in appearance, not flat, and atrophic as previously described; and (2) peripheral retinal drusen variably present in affected subjects, in contrast to the "normal peripheral retina" originally described. These new findings, along with the generally stable course of the disease would seem to alter our understanding of the relationship of NCMD to other dominant macular dystrophies.

Central pigmentary sheen dystrophy

Three members from two successive generations demonstrated a bilateral, symmetric pigmentary maculopathy consisting of a diffuse yellowish sheen of the posterior pole. The visual acuity was variable (20/25 to 10/400) and visual function tests indicated a localized disorder. Historic information suggests the disorder is slowly progressive. On the basis of mode of inheritance, fundus and angiographic appearance, and visual function testing this appears to be a newly described disorder.

Diphtheroids as ocular pathogens

Unlike Corynebacterium diphtheriae and Propionibacterium acnes, the pleomorphic gram-positive rods known as diphtheroids are generally regarded as nonpathogenic contaminants of the human external eye. We reviewed five years of microbiology records at Wills Eye Hospital and studied a series of eight cases of apparently infectious keratitis associated with heavy growth of diphtheroids on cultures of ulcer scrapings. All of these cases included indolent ulcers that occurred almost exclusively in elderly patients (mean age, 72 years; range, 11 to 92 years). All patients had preexisting ocular conditions that compromised the corneal surface such as exposed corneal sutures, eyelid surgery, aphakic extended wear contact lenses, viral keratitis, and diabetes mellitus. No other pathogens were isolated. All infections responded well to antibiotic therapy with all organisms sensitive to cefazolin and all but one sensitive to gentamicin.

Central areolar choroidal dystrophy in a family with pseudoachondroplastic spondyloepiphyseal dysplasia

The author reports the first association of central areolar choroidal dystrophy in three brothers with pseudoachondroplastic spondyloepiphyseal dysplasia. Both central areolar choroidal dystrophy and pseudoachondroplastic spondyloepiphyseal dysplasia represent heterogeneous disorders with autosomal dominant transmission. It is hypothesized that this association is a result of a new subtype involving both the skeletal system and the eye.

Autosomal dominant central pigment epithelial and choroidal degeneration

Eight of nine individuals of a four-generation family had autosomal dominant central pigment epithelial and choroidal degeneration, which was not entirely consistent with previously described central retinal and choroidal degenerations. The early loss of the choriocapillaris with a relative sparing of the sensory retinal and pigment epithelial function is similar to central areolar choroidal degeneration. Ophthalmoscopically, however, the disease resembled the dominant progressive foveal degenerations; except that our patients additionally had multiple peripheral yellow-white lesions. An exceptional finding in our patients was the preservation of good visual acuity despite marked atrophy of the choriocapillaris.

Annular macular dystrophy

Of 21 individuals from three generations of a single family with annular macular dystrophy, six showed only dyschromatopsia, one had dyschromatopsia and foveal hyperpigmentation, and four individuals had dyschromatopsia, foveal hyperpigmentation, and perifoveal circular pigment epithelial atrophy. Normal findings obtained on electrophysiologic testing suggest that this is a focal (macular) disorder rather than a generalized fundus disorder.

Fenestrated sheen macular dystrophy. A new autosomal dominant maculopathy

A family is described showing small, grouped, red fenestrations of the macular region surrounding an intact foveolar reflex. The disease affected a father and his 2 daughters, and seems to be an autosomal dominant maculopathy. No functional abnormalities were disclosed and fluorescein angiography was normal. This family may represent the second family described with fenestrated sheen macular dystrophy.

Dominantly inherited macular degeneration (Best's disease) in a homozygous father with 11 children

In Sweden, more than 250 cases of hereditary macular degeneration (HMD), inherited as an autosomal dominant trait and consistent with Best's disease, have been traced to one gene source in the 17th century. In this large material an apparently homozygous father was found, who was aged 56 and had 11 affected children. One of the children, aged 24, did not show any macular degeneration, but nevertheless she was considereds to be a carrier of the HMD-gene because she had pathological EOG-values. The great variations in expressivity of the disease in the 11 children reflected what has been found as a rule in large Swedish families with HMD. The homozygotic stage did not seem to differ in clinical appearance from the heterozygotic.