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Wyględowska-Promieńska D, Świerczyńska M, Śpiewak D, Pojda-Wilczek D, Tronina A, Dorecka M, Smędowski A. Aland Island Eye Disease with Retinoschisis in the Clinical Spectrum of CACNA1F-Associated Retinopathy-A Case Report. Int J Mol Sci 2024; 25:2928. [PMID: 38474172 DOI: 10.3390/ijms25052928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Revised: 02/26/2024] [Accepted: 02/29/2024] [Indexed: 03/14/2024] Open
Abstract
Aland island eye disease (AIED), an incomplete form of X-linked congenital stationary night blindness (CSNB2A), and X-linked cone-rod dystrophy type 3 (CORDX3) display many overlapping clinical findings. They result from mutations in the CACNA1F gene encoding the α1F subunit of the Cav1.4 channel, which plays a key role in neurotransmission from rod and cone photoreceptors to bipolar cells. Case report: A 57-year-old Caucasian man who had suffered since his early childhood from nystagmus, nyctalopia, low visual acuity and high myopia in both eyes (OU) presented to expand the diagnostic process, because similar symptoms had occurred in his 2-month-old grandson. Additionally, the patient was diagnosed with protanomalous color vision deficiency, diffuse thinning, and moderate hypopigmentation of the retina. Optical coherence tomography of the macula revealed retinoschisis in the right eye and foveal hypoplasia in the left eye. Dark-adapted (DA) 3.0 flash full-field electroretinography (ffERG) amplitudes of a-waves were attenuated, and the amplitudes of b-waves were abolished, which resulted in a negative pattern of the ERG. Moreover, the light-adapted 3.0 and 3.0 flicker ffERG as well as the DA 0.01 ffERG were consistent with severely reduced responses OU. Genetic testing revealed a hemizygous form of a stop-gained mutation (c.4051C>T) in exon 35 of the CACNA1F gene. This pathogenic variant has so far been described in combination with a phenotype corresponding to CSNB2A and CORDX3. This report contributes to expanding the knowledge of the clinical spectrum of CACNA1F-related disease. Wide variability and the overlapping clinical manifestations observed within AIED and its allelic disorders may not be explained solely by the consequences of different mutations on proteins. The lack of distinct genotype-phenotype correlations indicates the presence of additional, not yet identified, disease-modifying factors.
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Affiliation(s)
- Dorota Wyględowska-Promieńska
- Department of Ophthalmology, Faculty of Medical Sciences in Katowice, Medical University of Silesia, 40-514 Katowice, Poland
- Kornel Gibiński University Clinical Center, 40-514 Katowice, Poland
| | - Marta Świerczyńska
- Department of Ophthalmology, Faculty of Medical Sciences in Katowice, Medical University of Silesia, 40-514 Katowice, Poland
- Kornel Gibiński University Clinical Center, 40-514 Katowice, Poland
| | - Dorota Śpiewak
- Kornel Gibiński University Clinical Center, 40-514 Katowice, Poland
| | - Dorota Pojda-Wilczek
- Department of Ophthalmology, Faculty of Medical Sciences in Katowice, Medical University of Silesia, 40-514 Katowice, Poland
- Kornel Gibiński University Clinical Center, 40-514 Katowice, Poland
| | - Agnieszka Tronina
- Kornel Gibiński University Clinical Center, 40-514 Katowice, Poland
- Department of Pediatric Ophthalmology, Faculty of Medical Sciences in Katowice, Medical University of Silesia, 40-514 Katowice, Poland
| | - Mariola Dorecka
- Department of Ophthalmology, Faculty of Medical Sciences in Katowice, Medical University of Silesia, 40-514 Katowice, Poland
- Kornel Gibiński University Clinical Center, 40-514 Katowice, Poland
| | - Adrian Smędowski
- Department of Ophthalmology, Faculty of Medical Sciences in Katowice, Medical University of Silesia, 40-514 Katowice, Poland
- Kornel Gibiński University Clinical Center, 40-514 Katowice, Poland
- GlaucoTech Co., 40-282 Katowice, Poland
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A Novel Splice-Site Variant in CACNA1F Causes a Phenotype Synonymous with Åland Island Eye Disease and Incomplete Congenital Stationary Night Blindness. Genes (Basel) 2021; 12:genes12020171. [PMID: 33513752 PMCID: PMC7911795 DOI: 10.3390/genes12020171] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/22/2021] [Accepted: 01/25/2021] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND CACNA1F-related disorders encompass progressive and non-progressive disorders, including Åland island eye disease and incomplete congenital stationary night blindness. These two X-linked disorders are characterized by nystagmus, color vision defect, myopia, and electroretinography (ERG) abnormalities. Ocular hypopigmentation and iris transillumination are reported only in patients with Åland island eye disease. Around 260 variants were reported to be associated with these two non-progressive disorders, with 19 specific to Åland island eye disease and 14 associated with both Åland island eye disease and incomplete congenital stationary night blindness. CACNA1F variants spread on the gene and further analysis are needed to reveal phenotype-genotype correlation. CASE REPORT A complete ocular exam and genetic testing were performed on a 13-year-old boy. A novel splice-site variant, c.4294-11C>G in intron 36 in CACNA1F, was identified at hemizygous state in the patient and at heterozygous state in his asymptomatic mother and explained the phenotype synonymous with Åland island eye disease and incomplete congenital stationary night blindness observed in the patient. CONCLUSION We present a novel variant in the CACNA1F gene causing phenotypic and electrophysiologic findings indistinguishable from those of AIED/CSNB2A disease. This finding further expands the mutational spectrum and our knowledge of CACNA1F-related disease.
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Kruijt CC, de Wit GC, Bergen AA, Florijn RJ, Schalij-Delfos NE, van Genderen MM. The Phenotypic Spectrum of Albinism. Ophthalmology 2018; 125:1953-1960. [DOI: 10.1016/j.ophtha.2018.08.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 07/30/2018] [Accepted: 08/02/2018] [Indexed: 11/28/2022] Open
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Smirnov VM, Zeitz C, Soumittra N, Audo I, Defoort-Dhellemmes S. Retinal findings in a patient of French ancestry with CABP4-related retinal disease. Doc Ophthalmol 2018. [PMID: 29525873 DOI: 10.1007/s10633-018-9629-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
INTRODUCTION CABP4-related retinal dysfunction is a cone-rod synaptic transmission disorder with electronegative electroretinogram (ERG) waveform. It is a rare retinal dysfunction that can be classified into the incomplete form of congenital stationary night blindness. Absent foveal reflex and overall foveal thinning were previously reported, but in most cases the fundus appearance was described as nearly normal. We report here peculiar macular changes in a patient of French ancestry harbouring CABP4 mutations. METHODS Complete ocular examination and full-field ERG were performed at the initial presentation and follow-up. Multimodal fundus imagining, including spectral-domain optical coherence tomography, colour, infrared reflectance and short-wavelength autofluorescence photographs, was performed during follow-up visits. RESULTS A 7-month-old infant was addressed to our department for visual unresponsiveness and nystagmus. ERG had an electronegative waveform, even for light-adapted stimuli, thus supporting the diagnosis of photoreceptor-bipolar cell transmission disorder. Genetic investigations discovered a compound heterozygous mutation in CABP4: c.646C > T, p.Arg216*/c.673C > T, p.Arg225*. Multimodal fundus imaging, performed at follow-up visits, showed fine radial folds at the vitreomacular interface and dark foveal dots in both eyes. Optic coherence tomography revealed a focal foveal ellipsoid zone gap. DISCUSSION Initial presentation was misleading with Leber congenital amaurosis. The electronegative ERG waveform reoriented the genetic investigations and thus establishing a correct diagnosis. To the best of our knowledge, the peculiar fundus changes observed in our patient were never reported before. We hypothesized that a foveal ellipsoid zone interruption discovered in our patient could reflect mostly a cone dysfunction. It was unclear whether the fine radial folds in both maculae were linked with high hyperopia or were an intrinsic feature of the retinal disease. CONCLUSION CABP4-related retinal disease is a cone-rod system disorder with possible foveal abnormalities.
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Affiliation(s)
- Vasily Mikhaïlovitch Smirnov
- Exploration of Vision and Neuro-Ophthalmology Department, Lille University Hospital, Rue Emilie Laine, 59037, Lille Cedex, France. .,Faculté de Médecine, Université de Lille, 1, Place de Verdun, 59000, Lille Cedex, France.
| | - Christina Zeitz
- UPMC Univ Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, Sorbonne Universités, Paris, France
| | - Nagasamy Soumittra
- SN ONGC Department of Genetics and Molecular Biology, Vision Research Foundation, Chennai, India
| | - Isabelle Audo
- UPMC Univ Paris 06, INSERM U968, CNRS UMR 7210, Institut de la Vision, Sorbonne Universités, Paris, France.,DHU ViewMaintain, INSERM-DHOS CIC 1423, Centre Hospitalier National d'Ophtalmologie des Quinze-Vingts, Paris, France.,University College London Institute of Ophthalmology, London, UK
| | - Sabine Defoort-Dhellemmes
- Exploration of Vision and Neuro-Ophthalmology Department, Lille University Hospital, Rue Emilie Laine, 59037, Lille Cedex, France
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Hove MN, Kilic-Biyik KZ, Trotter A, Grønskov K, Sander B, Larsen M, Carroll J, Bech-Hansen T, Rosenberg T. Clinical Characteristics, Mutation Spectrum, and Prevalence of Åland Eye Disease/Incomplete Congenital Stationary Night Blindness in Denmark. Invest Ophthalmol Vis Sci 2017; 57:6861-6869. [PMID: 28002560 PMCID: PMC5215230 DOI: 10.1167/iovs.16-19445] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To assess clinical characteristics, foveal structure, mutation spectrum, and prevalence rate of Åland eye disease (AED)/incomplete congenital stationary night blindness (iCSNB). Methods A retrospective survey included individuals diagnosed with AED at a national low-vision center from 1980 to 2014. A subset of affected males underwent ophthalmologic examinations including psychophysical tests, full-field electroretinography, and spectral-domain optical coherence tomography. Results Over the 34-year period, 74 individuals from 35 families were diagnosed with AED. Sixty individuals from 29 families participated in a follow-up study of whom 59 harbored a CACNA1F mutation and 1 harbored a CABP4 mutation. Among the subjects with a CACNA1F mutation, subnormal visual acuity was present in all, nystagmus was present in 63%, and foveal hypoplasia was observed in 25/43 subjects. Foveal pit volume was significantly reduced as compared to normal (P < 0.0001). Additionally, outer segment length at the fovea was measured in 46 subjects and found to be significantly reduced as compared to normal (P < 0.001). Twenty-nine CACNA1F variations were detected among 34 families in the total cohort, and a novel CABP4 variation was identified in one family. The estimated mean birth prevalence rate was 1 per 22,000 live-born males. Conclusions Our data support the viewpoint that AED, iCSNB, and X-linked cone–rod dystrophy 3 are designations that refer to a broad, continuous spectrum of clinical appearances caused in the majority by a variety of mutations in CACNA1F. We argue that the original designation AED should be used for this entity.
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Affiliation(s)
- Marianne N Hove
- Department of Ophthalmology, National Eye Clinic for the Visually Impaired and Kennedy Center, Rigshospitalet, Glostrup, Denmark 2Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark
| | - Kevser Z Kilic-Biyik
- Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark 3Institute of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Alana Trotter
- Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Karen Grønskov
- Clinical Genetic Clinic, Kennedy Center, Rigshospitalet, Copenhagen, Denmark
| | - Birgit Sander
- Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark 3Institute of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Michael Larsen
- Department of Ophthalmology, National Eye Clinic for the Visually Impaired and Kennedy Center, Rigshospitalet, Glostrup, Denmark 2Department of Ophthalmology, Rigshospitalet, Glostrup, Denmark 3Institute of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Joseph Carroll
- Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Torben Bech-Hansen
- Department of Medical Genetics, Cumming School of Medicine, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada
| | - Thomas Rosenberg
- Department of Ophthalmology, National Eye Clinic for the Visually Impaired and Kennedy Center, Rigshospitalet, Glostrup, Denmark 3Institute of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Congenital stationary night blindness: An analysis and update of genotype–phenotype correlations and pathogenic mechanisms. Prog Retin Eye Res 2015; 45:58-110. [DOI: 10.1016/j.preteyeres.2014.09.001] [Citation(s) in RCA: 207] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 09/25/2014] [Accepted: 09/30/2014] [Indexed: 01/18/2023]
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A novel large in-frame deletion within the CACNA1F gene associates with a cone-rod dystrophy 3-like phenotype. PLoS One 2013; 8:e76414. [PMID: 24124559 PMCID: PMC3790679 DOI: 10.1371/journal.pone.0076414] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Accepted: 08/25/2013] [Indexed: 01/18/2023] Open
Abstract
Cone-rod dystrophies (CORDs) represent a heterogeneous group of monogenic diseases leading to early impairment of vision. The majority of CORD entities show autosomal modes of inheritance and X-linked traits are comparably rare. So far, three X-chromosomal entities were reported (CORDX1, -X2 and -X3). In this study, we analysed a large family of German origin with solely affected males over three generations showing a CORDX-like phenotype. Due to the heterogeneity of cone-rod dystrophies, we performed a combined linkage and X-exome sequencing approach and identified a novel large intragenic in-frame deletion encompassing exons 18 to 26 within the CACNA1F gene. CACNA1F is described causative for CORDX3 in a single family originating from Finland and alterations in this gene have not yet been reported in other CORDX pedigrees. Our data independently confirm CACNA1F as the causative gene for CORDX3-like phenotypes and detailed clinical characterization of the family expands the knowledge about the phenotypic spectrum of deleterious CACNA1F alterations.
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Audo I, Robson AG, Holder GE, Moore AT. The negative ERG: clinical phenotypes and disease mechanisms of inner retinal dysfunction. Surv Ophthalmol 2008; 53:16-40. [PMID: 18191655 DOI: 10.1016/j.survophthal.2007.10.010] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Inner retinal dysfunction is encountered in a number of retinal disorders, either inherited or acquired, as a primary or predominant defect. Fundus examination is rarely diagnostic in these disorders, although some show characteristic features, and careful electrophysiological assessment of retinal function is needed for accurate diagnosis. The ERG in inner retinal dysfunction typically shows a negative waveform with a preserved a-wave and a selectively reduced b-wave. Advances in retinal physiology and molecular genetics have led to a greater understanding of the pathogenesis of these disorders. This review summarizes current knowledge on normal retinal physiology, the investigative techniques used and the range of clinical disorders in which there is predominantly inner retinal dysfunction.
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Hawksworth NR, Headland S, Good P, Thomas NS, Clarke A. Aland island eye disease: clinical and electrophysiological studies of a Welsh family. Br J Ophthalmol 1995; 79:424-30. [PMID: 7612552 PMCID: PMC505128 DOI: 10.1136/bjo.79.5.424] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
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.
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Affiliation(s)
- N R Hawksworth
- Department of Ophthalmology, University Hospital of Wales, Cardiff
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Glass IA, Good P, Coleman MP, Fullwood P, Giles MG, Lindsay S, Nemeth AH, Davies KE, Willshaw HA, Fielder A. Genetic mapping of a cone and rod dysfunction (Aland Island eye disease) to the proximal short arm of the human X chromosome. J Med Genet 1993; 30:1044-50. [PMID: 7907666 PMCID: PMC1016646 DOI: 10.1136/jmg.30.12.1044] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A five generation family with an X linked ocular disorder has been investigated. The major clinical features were reduced visual acuity, nystagmus, and myopia. Although impaired night vision was not a symptom, using psychophysical and electrophysiological testing both rod and cone function were found to be abnormal in all affected males. No abnormality was detected in carrier females. Gene location studies showed X linked transmission of a gene that maps to proximal Xp11. The findings observed in this cohort are similar to those previously reported in both congenital stationary night blindness type 2 (CSNB2) and Aland Island eye disease (AIED). This study addresses whether CSNB2 and AIED are a single entity or whether the latter is a subset of the former.
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Affiliation(s)
- I A Glass
- Department of Pediatrics, School of Medicine, University of California, San Francisco 94143
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Lindsay S, Inglehearn CF, Curtis A, Bhattacharya S. Molecular genetics of inherited retinal degenerations. Curr Opin Genet Dev 1992; 2:459-66. [PMID: 1504622 DOI: 10.1016/s0959-437x(05)80158-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
There has recently been substantial progress in categorizing the vast range of human retinal degeneration phenotypes. A molecular approach has assigned chromosomal locations for approximately a dozen such diseases and has identified four of the genes involved.
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Affiliation(s)
- S Lindsay
- Molecular Genetics Unit Division of Human Genetics, University of Newcastle upon Tyne, UK
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Rosenberg T, Schwartz M, Simonsen SE. Aland eye disease (Forsius-Eriksson-Miyake syndrome) with probability established in a Danish family. Acta Ophthalmol 1990; 68:281-91. [PMID: 2392903 DOI: 10.1111/j.1755-3768.1990.tb01923.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A reinvestigation of a Danish family with X-linked inherited congenital nystagmus through 6 generations revealed a congenital stationary retinal dysfunction syndrome with characteristics of both incomplete congenital stationary night blindness and Aland Eye Disease. In spite of rather uniform electrophysiological findings in our patients, this retinal disorder which affects both cones and rods demonstrated considerable intrafamilial diversity with respect to visual acuity, nystagmus, refractive state and fundus pigmentation.
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Affiliation(s)
- T Rosenberg
- National Eye Clinic for the Visually Impaired, Copenhagen, Denmark
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Musarella MA, Weleber RG, Murphey WH, Young RS, Anson-Cartwright L, Mets M, Kraft SP, Polemeno R, Litt M, Worton RG. Assignment of the gene for complete X-linked congenital stationary night blindness (CSNB1) to Xp11.3. Genomics 1989; 5:727-37. [PMID: 2574143 DOI: 10.1016/0888-7543(89)90114-6] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
X-linked congenital stationary night blindness (CSNB) is a nonprogressive retinal disorder characterized by a presumptive defect of neurotransmission between the photoreceptor and bipolar cells. Carriers are not clinically detectable. A new classification for CSNB includes a complete type, which lacks rod function by electroretinography and dark adaptometry, and an incomplete type, which shows some rod function on scotopic testing. The refraction in the complete CSNB patients ranges from mild to severe myopia; the incomplete ranges from moderate hyperopia to moderate myopia. To map the gene responsible for this disease, we studied eight multigeneration families, seven with complete CSNB (CSNB1) and one with incomplete CSNB, by linkage analysis using 17 polymorphic X-chromosome markers. We found tight genetic linkage between CSNB1 and an Xp11.3 DNA polymorphic site, DXS7, in seven families with CSNB1 (LOD 7.35 at theta = 0). No recombinations to CSNB1 were found with marker loci DXS7 and DXS14. The result with DXS14 may be due to the small number of scored meioses (10). No linkage could be shown with Xq loci PGK, DXYS1, DXS52, and DXS15. Pairwise linkage analysis maps the gene for CSNB1 at Xp11.3 and suggests that the CSNB1 locus is distal to another Xp11 marker, TIMP, and proximal to the OTC locus. Five-point analysis on the eight families supported the order DXS7-CSNB1-TIMP-DXS225-DXS14. The odds in favor of this order were 9863:1. Removal of the family with incomplete CSNB (F21) revealed two most favored orders, DXS7-CSNB1-TIMP-DXS255-DXS14 and CSNB1-DXS7-TIMP-DXS255-DXS14. Heterogeneity testing using the CSNB1-M27 beta and CSNB1-TIMP linkage data (DXS7 was not informative in F21) was not significant to support evidence of genetic heterogeneity (P = 0.155 and 0.160, respectively).
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Affiliation(s)
- M A Musarella
- Department of Ophthalmology, Hospital for Sick Children, Toronto, Ontario, Canada
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Affiliation(s)
- C J Witkop
- Department of Oral Pathology and Genetics, University of Minnesota School of Dentistry, Minneapolis
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Abstract
UNLABELLED After a 4-year multidisciplinary study of albinism our findings will be presented here. Over a hundred albinos were examined, together with their heterozygote family members. Given this substantial patient and subject sample we were provided with the opportunity to: evaluate the results of standard diagnostic procedures, for example pedigree analysis, ocular and clinical examination; determine the diagnostic value of biochemical, and ultrastructural tests; and develop a new and viable albino diagnostic protocol, particularly for electrophysiological examination. In the conclusions the following subjects are in order: DIAGNOSIS Our most important finding up till now is that normally pigmented people who do not look like albinos can in fact be albinos. DIFFERENTIAL DIAGNOSIS It appears that patients with autosomal recessive albinism can be normally pigmented, and patients with X-linked albinism can be severely hypopigmented. We therefore propose to abandon the terms oculo-cutaneous albinism (OCA), and X-linked ocular albinism (XOA), and use the terms autosomal recessive albinism, and X-linked albinism instead. X-linked albinism Forsius-Eriksson type (XOAF): We assume that XOAF does not represent a true form of albinism. CLASSIFICATION Our results indicate that the phenotypical albino classification, which was a base for Witkop et al. (1978) to also obtain a genetical classification, supported by the hairbulb test, has not proved to be useful for the classification of tyrosinase negative (TNOCA), tyrosinase positive oculocutaneous albinism (TPOCA), and autosomal recessive ocular albinism (AROA) as genetically distinct forms. Prevalence: Our prevalence estimate for all forms of albinism is at least 1:15,000, about 10% of the albinos have X-linked albinism. DEFINITION We want to modify the albino definition as a hereditary and congenital inborn error of metabolism related to the pigment cell, and resulting in a systemic disorder that is characterized by anomalies of eyes, and hypopigmentation in most cases or absence of pigment in skin, hair, and eyes, and of which the neuro-anatomical consequences are the most characteristic.
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