Surgical Removal of Subretinal Neovascular Membranes

Since 1991 we have been gaining experience in the surgical removal of submacular subretinal membranes in patients with presumed ocular histoplasmosis syndrome (POHS), idiopathic subretinal neovascularisation, myopia and age-related macular degeneration (AMD). Seventeen patients were operated between 1991 and 1993. Significant improvement of vision was achieved in 4 out of 5 patients with POHS, 3 out of 5 with idiopathic neovascularisation, 2 out of 4 with myopia but none of 3 patients with AMD. The results suggest that subretinal neovascularisation can be successfully removed in POHS and in some forms of idiopathic neovascularisation and myopia but probably not in AMD.

Visual impairment in Finnish Usher syndrome type III

PURPOSE

To evaluate visual impairment in Finnish Usher syndrome type 3 (USH3) and compare this with visual impairment in Usher syndrome types 1b (USH1b) and 2a (USH2a).

METHODS

We carried out a retrospective study of 28 Finnish USH3 patients, 24 Dutch USH2a patients and 17 Dutch USH1b patients. Cross-sectional regression analyses of the functional acuity score (FAS), functional field score (FFS*) and functional vision score (FVS*) related to age were performed for all patients. The FFS* and FVS* were calculated using the isoptre V-4 test target instead of the usual III-4 target. Statistical tests relating to regression lines and Student's t-test were used to compare between USH3 patients and the other genetic subtypes of Usher syndrome.

RESULTS

Cross-sectional analyses revealed significant deterioration in the FAS (1.3% per year), FFS* (1.4% per year) and FVS* (1.8% per year) with advancing age in the USH3 patient group. At a given age the USH3 patients showed significantly poorer visual field function than the USH2a patients.

CONCLUSIONS

The rate of deterioration in visual function in Finnish USH3 patients was fairly similar to that in Dutch USH1b or USH2a patients. At a given age, visual field impairment in USH3 patients was similar to that in USH1b patients but poorer than in USH2a patients.

Impact factors on intraocular pressure measurements in healthy subjects

AIM

To evaluate whether intraocular pressure (IOP) calculation by applanation tonometry is determined more essentially by the subject's neck position or by neck constriction.

METHODS

23 right eyes of 23 healthy subjects (12 male, 11 female) were included. IOP was measured by applanation tonometry with the TonoPen on sitting participants under four different conditions: with open collar upright (A) or with the head in the headrest of a slit lamp (B), with a tight necktie upright (C) or in slit lamp position (D). All measurements with neck constriction were performed 3 minutes after placing the necktie.

RESULTS

Mean IOP was 16.9 (SD 2.3) mm Hg (range 11-21 mm Hg) (A), 18.1 (SD 2.2) mm Hg (range 14-22 mm Hg) (B), 17.9 (SD 2.9) mm Hg (range 12-25 mm Hg) (C) and 18.7 (SD 2.7) mm Hg (range 13-24 mm Hg) (D). Mean IOP increased by 1.3 (SD 2.6) mm Hg (p = 0.028, paired t test, range +0.2 to +2.4 mm Hg) if subjects changed position from A to B. There was no statistically significant difference between measurements with or without neck constriction.

CONCLUSION

Applanation tonometry may be inaccurate if performed in slit lamp position. In contrast, tight neckties do not significantly affect IOP evaluation in healthy subjects.

The spectrum of retinal phenotypes caused by mutations in the ABCA4 gene

BACKGROUND

The majority of studies on the retina-specific ATP-binding cassette transporter (ABCA4) gene have focussed on molecular genetic analysis; comparatively few studies have described the clinical aspects of ABCA4-associated retinal disorders. In this study, we demonstrate the spectrum of retinal dystrophies associated with ABCA4 gene mutations.

METHODS

Nine well-documented patients representing distinct phenotypes in the continuum of ABCA4-related disorders were selected. All patients received an extensive ophthalmologic evaluation, including kinetic perimetry, fluorescein angiography, and electroretinography (ERG). Mutation analysis had been performed previously with the genotyping microarray (ABCR400 chip) and/or single-strand conformation polymorphism analysis in combination with direct DNA sequencing.

RESULTS

In all patients, at least one pathologic ABCA4 mutation was identified. Patient 10034 represented the mild end of the phenotypic spectrum, demonstrating exudative age-related macular degeneration (AMD). Patient 24481 received the diagnosis of late-onset fundus flavimaculatus (FFM), patient 15168 demonstrated the typical FFM phenotype, and patient 19504 had autosomal recessive Stargardt disease (STGD1). Patients 11302 and 7608 exhibited progression from FFM/STGD1 to cone-rod dystrophy (CRD). A more typical CRD phenotype was found in patients 15680 and 12608. Finally, the most severe ABCA4-associated phenotype was retinitis pigmentosa (RP) in patient 11366. This phenotype was characterised by extensive atrophy with almost complete loss of peripheral and central retinal functions.

CONCLUSION

We describe nine patients during different stages of disease progression; together, these patients form a continuum of ABCA4-associated phenotypes. Besides characteristic disorders such as FFM/STGD1, CRD and RP, intermediate phenotypes may be encountered. Moreover, as the disease progresses, marked differences may be observed between initially comparable phenotypes. In contrast, distinctly different phenotypes may converge to a similar final stage, characterised by extensive chorioretinal atrophy and very low visual functions. The identified ABCA4 mutations in most, but not all, patients were compatible with the resulting phenotypes, as predicted by the genotype-phenotype model for ABCA4-associated disorders. With the advent of therapeutic options, recognition by the general ophthalmologist of the various retinal phenotypes associated with ABCA4 mutations is becoming increasingly important.

Variable clinical features in patients with CDH23 mutations (USH1D-DFNB12)

OBJECTIVE

To describe the findings of audiovestibular and ophthalmologic examinations in four families with mutations in the CDH23 gene.

STUDY DESIGN

Family study.

SETTING

Tertiary referral center.

PATIENTS

Four DFNB12 patients from a large consanguineous Dutch family and six patients from three different Usher syndrome Type ID families were examined. All were identified by at least one pathogenic mutation in the CDH23 gene.

METHODS

Audiovestibular examinations consisted of standard pure-tone audiometry, vestibulo-ocular reflex, optokinetic nystagmus, and in some cases the cervico-ocular reflex. Linear regression analysis was used to evaluate progression of hearing impairment, and the degree of hearing impairment of DFNB12 was compared with that found for USH1D. Ophthalmologic examinations consisted of best-corrected visual acuity, Goldmann perimetry, slit-lamp examinations, color vision testing, dark adaptation, electroretinography, electro-oculography, funduscopy and photography of the retina, and sometimes fluorescein angiography.

RESULTS

The USH1D patients had significantly worse hearing impairment than the DFNB12 patients. The DFNB12 patients, identified by missense mutations in CDH23, had normal retinal and vestibular function. All USH1D patients had splice-site mutations in CDH23 and a typical Usher syndrome Type I phenotype. One DFNB12 patient had slightly abnormal yellowish flecks in the posterior poles of both eyes.

CONCLUSION

Recessive missense mutations in CDH23 lead to a milder phenotype (DFNB12) than splice-site mutations (USH1D); however, abnormal bilateral flecks, suggestive for lipofuscin accumulation, can be observed in DFNB12 patients.

USH2A mutation analysis in 70 Dutch families with Usher syndrome type II

Usher syndrome type II (USH2) is characterised by moderate to severe high-frequency hearing impairment, progressive visual loss due to retinitis pigmentosa and intact vestibular responses. Three loci are known for USH2, however, only the gene for USH2a (USH2A) has been identified. Mutation analysis of USH2A was performed in 70 Dutch USH2 families. Ten mutations in USH2A were detected, of which three are novel, c.949C>A, c.2242C>T (p.Gln748X) and c.4405C>T (p.Gln1468X). Including 9 previously published Dutch USH2a families, estimates of the prevalence of USH2a in the Dutch USH2 population were made. Mutations were identified in 62% of the families. In 28% both mutated alleles were identified, whereas in 34% the mutation in only one allele was found. It is estimated that about 28% of the Dutch USH2 families have a different causative gene. Analysis of deduced haplotypes suggests that c.1256G>T (p.Cys419Phe) is a Dutch ancestral mutation, occurring in 16% of the alleles.

Autosomal dominant rhegmatogenous retinal detachment--clinical appearance and surgical outcome

PURPOSE

To study the clinical appearance and surgical results of autosomal dominantly inherited rhegmatogenous retinal detachments (RRDs).

METHODS

After prospective examination of all but two family members, the medical records of 16 affected patients (21 eyes) of two families from the Netherlands with autosomal dominantly inherited RRD were retrospectively evaluated. Special attention was paid to the age at onset, the ocular morphology and the clinical appearance of the RRD. The type and number of the various surgical procedures were analyzed with respect to preoperative appearance of the RRD, postoperative results and final visual acuity.

RESULTS

The mean age at onset of RRD of affected individuals in families A and B was 37 +/- 18 years and 19 +/- 10 years, respectively. The mean ocular axial length in the two families was 24.7 mm and 26.7 mm. The mean number of retinal defects preoperatively found was 2.2 in family A and 7.1 in family B. Round, atrophic retinal holes predominated. Two of 21 affected eyes showed significant preoperative proliferative vitreoretinopathy. Pars plana vitrectomy was the primary procedure in 4 cases; extra ocular buckling was the initial procedure in 15 cases. One eye received scleral folding with diathermy as primary surgery. Redetachment following surgery occurred in 5 of 10 cases in family A and 4 of 10 eyes in family B. Anatomical success could be achieved in 9 of 10 and 8 of 10 eyes in families A and B, respectively.

CONCLUSIONS

In these families the prevalence of RRD is high. Most patients were affected at a relatively young age compared with non-genetically linked forms of RRD. Because of the low success rate of surgical intervention and, subsequently, the high number of operations necessary to achieve reattachment of the retina, the use of diagnostic genetic techniques to identify individuals at risk would be advisable. In these subjects measures to prevent RRD are an option, even when anatomical substrates of precursors of RRD are absent.

Evaluation of visual impairment in Usher syndrome 1b and Usher syndrome 2a

PURPOSE

To evaluate visual impairment in Usher syndrome 1b (USH1b) and Usher syndrome 2a (USH2a).

METHODS

We carried out a retrospective study of 19 USH1b patients and 40 USH2a patients. Cross-sectional regression analyses of the functional acuity score (FAS), functional field score (FFS) and functional vision score (FVS) related to age were performed. Statistical tests relating to regression lines and Student's t-test were used to compare between (sub)groups of patients. Parts of the available individual longitudinal data were used to obtain individual estimates of progressive deterioration and compare these to those obtained with cross-sectional analysis. Results were compared between subgroups of USH2a patients pertaining to combinations of different types of mutations.

RESULTS

Cross-sectional analyses revealed significant deterioration of the FAS (0.7% per year), FFS (1.0% per year) and FVS (1.5% per year) with advancing age in both patient groups, without a significant difference between the USH1b and USH2a patients. Individual estimates of the deterioration rates were substantially and significantly higher than the cross-sectional estimates in some USH2a cases, including values of about 5% per year (or even higher) for the FAS (age 35-50 years), 3-4% per year for the FFS and 4-5% per year for the FVS (age > 20 years). There was no difference in functional vision score behaviour detected between subgroups of patients pertaining to different biallelic combinations of specific types of mutations.

CONCLUSIONS

The FAS, FFS and FVS deteriorated significantly by 0.7-1.5% per year according to cross-sectional linear regression analysis in both USH1b and USH2a patients. Higher deterioration rates (3-5% per year) in any of these scores were attained, according to longitudinal data collected from individual USH2a patients. Score behaviour was similar across the patient groups and across different biallelic combinations of various types of mutations. However, more elaborate studies, preferably covering longitudinal data, are needed to obtain conclusive evidence.

The benign concentric annular macular dystrophy locus maps to 6p12.3-q16

PURPOSE

To describe the clinical findings and to identify the genetic locus in a Dutch family with autosomal dominant benign concentric annular macular dystrophy (BCAMD).

METHODS

All family members underwent ophthalmic examination. Linkage analysis of candidate retinal dystrophy loci and a whole genome scan were performed. Five candidate genes from the linked locus were analyzed for mutations by direct sequencing.

RESULTS

The BCAMD phenotype is initially characterized by parafoveal hypopigmentation and good visual acuity, but progresses to a retinitis pigmentosa-like phenotype. Linkage analysis established complete segregation of the BCAMD phenotype (maximum multipoint LOD score, 3.8) with DNA markers at chromosome 6, region p12.3-q16. Recombination events defined a critical interval spanning 30.7 cM at the long arm of chromosome 6 between markers D6S269 and D6S300. This interval encompasses several retinal dystrophy loci, including the ELOVL4 gene, mutated in autosomal dominant Stargardt disease, and the RIM1 gene, mutated in autosomal dominant cone-rod dystrophy, as well as the retinally expressed GABRR1 and -2 genes. Mutation screening of these four genes revealed no mutations. Sequence analysis of the interphotoreceptor matrix proteoglycan 1 gene IMPG1, also residing in the BCAMD locus, revealed a single base-pair change (T-->C) of nucleotide 1866 in exon 13, resulting in a Leu579Pro amino acid substitution. This mutation was absent in 190 control individuals.

CONCLUSIONS

Significant linkage was found for the BCAMD defect with chromosomal 6, region p12.3-q16. A Leu579Pro mutation in the IMPG1 gene may play a causal role.

Endogenous endophthalmitis after otitis media

PURPOSE

To report a case of bacterial endophthalmitis after otitis media in a healthy adult.

DESIGN

Interventional case report.

METHODS

A healthy 49-year-old Caucasian woman developed acute otitis media of the right ear. Three weeks after the first onset there was a recurrence of the otitis media, with perforation of the tympanic membrane. Two days after this, the woman presented at our clinic with endophthalmitis of the right eye.

RESULTS

A culture of vitreous material grew Streptococcus pyogenes (Streptococcus Lancefield group A). The same strain was found in a smear from the perforated ear. Despite aggressive treatment, the affected eye had to be eviscerated.

CONCLUSIONS

Otitis media can result in a bacteremia. This may, even in a healthy adult, lead to a devastating endogenous bacterial endophthalmitis.

A Peculiar Autosomal Dominant Macular Dystrophy Caused by an Asparagine Deletion at Codon 169 in the Peripherin/RDS Gene

OBJECTIVE

To describe the clinical and genetic findings in a family with a peculiar autosomal dominant macular dystrophy with peripheral deposits.

METHODS

All family members underwent an ophthalmic examination, and their genomic DNA was screened for mutations in the human retinal degeneration slow (peripherin/RDS) and rhodopsin genes. In selected cases, fluorescein angiography and electrophysiologic testing were performed.

RESULTS

The age at onset of the disease was between the third and fourth decades of life, starting with mild visual acuity loss and periods of metamorphopsia. Clinical signs included subretinal yellowish macular deposits evolving into geographic atrophy and retinal hypopigmentation and hyperpigmentation. Electroretinography demonstrated rod dysfunction, and electro-oculograms were mildly to severely disturbed. All affected members were found to carry a 3-base pair deletion affecting codon 169 of the peripherin/RDS gene. This mutation resulted in an asparagine (Asn) deletion in the peripherin/RDS protein and was not found in 155 control individuals.

CONCLUSION

A deletion of Asn169 in the peripherin/RDS protein causes a peculiar form of autosomal dominant macular dystrophy in a large family from the Netherlands.

CLINICAL RELEVANCE

Characterizing the phenotype and genotype in this family may, in the long term, result in a better understanding of the precise mechanism underlying this retinal degeneration.

Bilateral detachment of the macular neuroepithelium in a patient with Klinefelter syndrome

PURPOSE

To describe the occurrence of atypical, bilateral detachment of the macular neuroepithelium and Klinefelter syndrome in a young patient.

METHODS

Case report.

RESULTS

A 20-year-old male of Chinese origin with karyotype 47,XXY presented with bilateral central neurosensory retinal detachment. There was spontaneous improvement.

CONCLUSIONS

An atypical form of detachment of the macular neuroepithelium was seen in a young patient with Klinefelter syndrome. The pathophysiological mechanism is not clear. The possibility of a hormonal imbalance is discussed. A differential diagnostic consideration is central serous chorioretinopathy and a mild form of Vogt-Koyanagi-Harada syndrome. This case is of interest because of the rarity of association between Klinefelter syndrome and chorioretinal abnormalities.

Usher syndrome type III can mimic other types of Usher syndrome

Clinical and genetic characteristics are presented of 2 patients from a Dutch Usher syndrome type III family who have a new homozygous USH3 gene mutation: 149-152delCAGG + insTGTCCAAT. One individual (IV:1) is profoundly hearing impaired and has normal vestibular function and retinitis punctata albescens (RPA). The other individual is also profoundly hearing impaired, but has well-developed speech, vestibular areflexia, and retinitis pigmentosa sine pigmento (RPSP). These findings suggest that Usher syndrome type III can be clinically misdiagnosed as either Usher type I or II; that Usher syndrome patients who are profoundly hearing impaired and have normal vestibular function should be tested for USH3 mutations; and that RPA and RPSP can occur as fundoscopic manifestations of pigmentary retinopathy in Usher syndrome.

Genetic heterogeneity of butterfly-shaped pigment dystrophy of the fovea

PURPOSE

Butterfly-shaped macular dystrophy (BSMD) has so far only been associated with mutations in the peripherin/RDS gene. The initial aim of our study was to investigate the peripherin/RDS gene as the causative gene in a family with BSMD. Subsequently the putative involvement of the ROM-1 gene, 4 genes expressed in cone photoreceptors, all known non-syndromic macular, retinal pigment epithelium and choroidal dystrophy loci, all known Leber congenital amaurosis loci and all known non-syndromic congenital and stationary retinal disease loci was examined.

METHODS

Thirteen members from the original family with autosomal dominant BSMD were examined. The protein coding exons of the peripherin/RDS gene were screened for mutations by sequence analysis. Linkage analysis was performed using markers flanking the peripherin/RDS gene to rule out the presence of a heterozygous deletion. Likewise, involvement of the ROM-1 gene, four cone genes, 41 non-syndromic retinal disease loci and one syndromic retinal disease locus was investigated.

RESULTS

Sequence analysis of the peripherin/RDS gene revealed no mutations. In addition, the BSMD phenotype could not be genetically linked to the peripherin/RDS gene, the ROM-1 gene and the four cone genes nor to any of the 42 retinal disease loci.

CONCLUSIONS

This study reveals genetic heterogeneity for BSMD by the identification of a BSMD family, which is not associated with a mutation in the peripherin/RDS gene nor with any other known non-syndromic retinal disease gene.

Peripheral retinal nonperfusion associated with chronic myeloid leukemia

PURPOSE

To report a case of peripheral retinal nonperfusion and chronic myeloid leukemia in a 23-year-old woman.

DESIGN

Observational case report.

METHODS

A complete ophthalmic and systemic evaluation was performed.

RESULTS

Ophthalmic examination revealed peripheral retinal nonperfusion with retinal neovascularization in both eyes. Fluorescein angiography of both eyes showed a marked midperipheral and peripheral avascular retina temporally with arteriovenous anastomosis and seafan neovascularizations. Blood work showed no abnormalities, although marked leucocytosis (up to 750 x 10(9)/l) and thrombocytosis (646 x 10(9)/l) were present in 1998 when the patient was diagnosed with leukemia. Following treatment, the patient has been in remission.

CONCLUSIONS

Peripheral retinal nonperfusion with retinal neovascularization may occur as a complication of chronic myeloid leukemia. In contrast to other studies describing this association, our patient had a bilateral peripheral retinal nonperfusion with seafan neovascularizations without relapse of the myeloid leukemia and without any of the other retinal signs associated with chronic myeloid leukemia, such as tortuosity of veins, intraretinal or preretinal hemorrhages, and cotton-wool exudates.

Mutations in the calcium-binding motifs of CDH23 and the 35delG mutation in GJB2 cause hearing loss in one family

We have ascertained a multi-generation family with apparent autosomal recessive non-syndromic childhood hearing loss (DFNB). Failure to demonstrate linkage in a genome-wide scan with 300 polymorphic markers has suggested genetic heterogeneity for the hearing loss in this family. This heterogeneity could be demonstrated by analysis of candidate loci and genes for DFNB. Patients in one branch of the family (branch C) are homozygous for the 35delG mutation in the GJB2 gene (DFNB1). Patients in two other branches (A and B) carry two new mutations in the cadherin 23 ( CDH23) gene (DFNB12). A homozygous CDH23 c.6442G-->A (D2148N) mutation is present in branch A. Patients in branch B are compound heterozygous for this mutation and the c.4021G-->A (D1341N) mutation. The substituted aspartic acid residues are highly conserved and are part of the calcium-binding sites of the extracellular cadherin (EC) domains. Molecular modeling of the mutated EC domains of CDH23 based on the structure of E-cadherin indicates that calcium-binding is impaired. In addition, other aspartic and glutamic acid residue substitutions in the highly conserved calcium-binding sites reported to cause DFNB12 are also likely to result in a decreased affinity for calcium. Since calcium provides rigidity to the elongated structure of cadherin molecules enabling homophilic lateral interaction, these mutations are likely to impair interactions of CDH23 molecules either with CDH23 or with other proteins. DFNB12 is the first human disorder that can be attributed to inherited missense mutations in the highly conserved residues of the extracellular calcium-binding domain of a cadherin.

[From gene to disease; genetic causes of hearing loss and visual impairment sometimes accompanied by vestibular problems (Usher syndrome)]

Usher syndrome is an autosomal recessively inherited disease, characterised by sensorineural hearing loss, tapetoretinal degeneration and in some cases vestibular problems. Based on the clinical heterogeneity, the disease can be classified into three clinical types (I, II and III), which have their own genetic subtypes (Usher 1A-Usher IG, Usher 2A-Usher 2C and Usher 3). The majority of the Usher type I cases are caused by mutations in the MYO7A gene (Usher 1B) while mutations in the USH2A gene (Usher 2A) are the cause of most cases of type II. Usher syndrome type III, caused by mutations in the USH3 gene, is frequently seen only in Finland.

Side effects after radiotherapy of age-related macular degeneration with the Nijmegen technique

BACKGROUND

In a randomized trial concerning radiotherapy for age-related macular degeneration, fluorescein angiograms were taken of controls and patients. In this study the frequency of side effects in eyes receiving radiotherapy with the Nijmegen technique is compared with the findings in the eyes of controls.

METHODS

Patients receiving treatment were irradiated by two isocentric photon beams in four fractions of 6 Gy that were directed to the macular area at 30 degrees and -30 degrees with regard to the optical axis. The most recent fluorescein angiograms of the randomized eyes (32 treated and 31 control eyes) were scored by two independent researchers, using a scoring form with nine features of radiation retinopathy: nonperfusion, macular edema, microaneurysms, retinal hemorrhages, cotton-wool spots, perifoveal telangiectasis, vascular sheathing, retinal neovascularization, and radiation-associated choroidal neovasculopathy. The results were graded as: no retinopathy (grade 0), mild retinopathy (grade 1), moderate retinopathy (grade 2), and severe retinopathy (grade 3).

RESULTS

In the treated group 6 patients (18.8%) were grade 1, 10 patients (31.2%) were grade 2 and 7 patients (21.9%) were grade 3. In the control group 9 patients (29.0%) were grade 1, 11 patients (35.5%)were grade 2 and 2 patients (6.5%) were grade 3. There were no patients with retinal neovascularization.

CONCLUSION

With the Nijmegen technique a relatively high dose of radiation can be applied to a small retinal area. In only a minority of cases does some evidence of radiation retinopathy occur.

Autosomal recessive cerebellar ataxia with bull's-eye macular dystrophy

PURPOSE

In 1980, we published in the American Journal of Ophthalmology two siblings with hereditary ataxia and atrophic maculopathy. The report is cited in the literature as autosomal dominant cerebellar ataxia with retinal degeneration. The purpose of the present study is to document the progression of the neurodegenerative disorder and to review the diagnosis.

DESIGN

Observational case report.

METHODS

Twenty years after the original publication, the 52-year-old male patient had new ocular and neurologic examinations, fluorescein angiography, molecular genetic analysis, and biochemical testing.

RESULTS

Fluorescein angiography showed marked progression of the macular dystrophy to a bull's-eye configuration. Genetic analysis of the patient did not show CAG trinucleotide repeat expansion in the various spinocerebellar ataxia genes. This excludes the diagnosis of autosomal dominant cerebellar ataxia with macular degeneration (ADCA type II) with mutation of the spinocerebellar ataxia 7 gene. Major causes of autosomal recessive cerebellar ataxia with retinal degeneration, including Friedreich ataxia and congenital disorders of glycosylation, were also excluded.

CONCLUSION

The two patients, previously published in the American Journal of Ophthalmology by Eerola and coworkers, did not suffer from presently recognized disorders with cerebellar ataxia and retinal degeneration. The Eerola syndrome probably represents a separate neurodegenerative entity characterized by autosomal recessive cerebellar ataxia and progressive macular dystrophy with a bull's-eye pattern.

Clinical characterization, linkage analysis, and PRPC8 mutation analysis of a family with autosomal dominant retinitis pigmentosa type 13 (RP13)

A Dutch family with autosomal dominant retinitis pigmentosa (adRP) displayed a phenotype characterized by an early age of onset, a diffuse loss of rod and cone sensitivity, and constricted visual fields (type I). One male showed a mild progression of the disease. Linkage analysis showed cosegregation of the genetic defect with markers from chromosome 17p13.1-p13.3, a region overlapping the RP13 locus. The critical interval of the RP locus as defined in this family was flanked by D17S926 and D17S786, with a maximal lod score of 4.2 (theta = 0.00) for marker D17S1529. Soon after the mapping of the underlying defect to the 17p13 region, a missense mutation (6970G>A; R2310K) was identified in exon 42 of the splicing factor gene PRPC8 in one patient of this family. Diagnostic restriction enzyme digestion of exon 42 amplified from genomic DNA of all family members revealed that the R2310K mutation segregated fully with the disease. The type I phenotype observed in this family is similar to that described for three other RP13 families with mutations in PRPC8.

Central areolar choroidal dystrophy associated with dominantly inherited drusen

AIM

To describe the clinical and genetic aspects of a retinal dystrophy that combines central areolar choroidal dystrophy (CACD) and autosomal dominantly inherited drusen.

METHODS

The members of three unrelated families who demonstrated the rare combination of CACD and dominant drusen were clinically and angiographically investigated. In addition, DNA samples from the members of these families were screened for the Arg142Trp mutation in the peripherin/retinal degeneration slow (RDS) gene.

RESULTS

The severity of the CACD/dominant drusen maculopathy was age related and the expression of the phenotype varied. All affected individuals carried the Arg142Trp mutation in the peripherin/RDS gene. The clinical spectrum ranged from CACD without noticeable drusen in four individuals to the fully expressed phenotype of CACD with drusen in 14 individuals.

CONCLUSION

CACD macular dystrophy is associated with dominant drusen in most individuals carrying the Arg142Trp mutation in the peripherin/RDS gene in the three families described. There are no individuals with dominant drusen in the absence of the Arg142Trp mutation, suggesting that the Arg142Trp mutation is one of the factors predisposing to drusen development.