The Phenotypic Spectrum of Albinism

Kruijt, Charlotte C.; Wit, Gerard C. de; Bergen, Arthur A. B.; Florijn, Ralph J.; Schalij‐Delfos, Nicoline E.; Genderen, Maria M. van

doi:10.1016/j.ophtha.2018.08.003

Cited by 96 publications

(138 citation statements)

References 27 publications

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“…Recent studies showed that albinism is a much more heterogeneous disorder than previously thought. 1,[19][20][21] Accurate assessment of chiasmal misrouting may greatly aid in the diagnosis of mildly affected albinism subjects. The aim of our study was to compare multichannel VEPs of a phenotypically heterogeneous group of albinism subjects to controls with and without ocular pathology, in order to optimize VEP procedures and to investigate if previous recommendations are still appropriate for clinical use.…”

Section: Discussionmentioning

confidence: 99%

“…For all other albinism features, including foveal hypoplasia and ocular hypopigmentation, there are (genetically confirmed) albinism patients lacking these features. 1 It may, therefore, very well be that also misrouting is absent in some patients. A further confirmation of normal routing proved to be the good stereoacuity that we measured in some of our patients.…”

Section: Discussionmentioning

confidence: 99%

“…All albinism subjects met the previously described diagnostic criteria. 1 The diagnoses in the control group are described in Table 1. We divided albino subjects and controls in three age groups according to the recommendations of Apkarian 4 : younger than 3 years (albinism, n ¼ 55; controls, n ¼ 51), 3 to 6 years (toddlers) (albinism, n ¼ 32; controls, n ¼ 34), and 6 years of age and older (albinism, n ¼ 93; controls, n ¼ 102).…”

Section: Subjectsmentioning

confidence: 99%

“…Therefore, major and minor diagnostic criteria were recently introduced. 1 Major criteria are ocular hypopigmentation, foveal hypoplasia grade 2 or more, and misrouting. Misrouting in albinism is characterized by a majority of the optic nerve fibers crossing at the chiasm and projecting to the contralateral hemisphere, resulting in a reduced or delayed signal in the ipsilateral hemisphere.…”

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confidence: 99%

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The Detection Of Misrouting In Albinism: Evaluation of Different VEP Procedures in a Heterogeneous Cohort

Kruijt

Wit

Talsma

et al. 2019

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. To investigate the optimal procedures for multichannel visually evoked potentials (VEPs) to detect misrouting in albinism subjects. METHODS. Investigations were done in a phenotypically heterogeneous group of 180 albinism subjects and 187 controls with and without ocular pathology. We retrospectively compared standard flash VEP (fVEP), high-frequency fVEP with a handheld device (hh fVEP), patternonset VEP (poVEP), and short-onset acuity sweep VEP. The diagnostic power of these stimuli were estimated by calculating the area under the curve (AUC). Subjects were divided in three age groups (<3, 3-6 [toddler], and ‡6 years). Subjects ‡6 years of age were further divided in two visual acuity groups (0.3 logMAR and >0.3 logMAR). RESULTS. The optimal stimulus was hh fVEP, standard fVEP, and poVEP 60 0 for subjects <3, 3-6, and ‡6 years of age, respectively. In subjects ‡6 years old with poor visual acuity, the area under the curve of fVEP was almost equal to that of poVEP 60 0. CONCLUSIONS. For the optimal detection of misrouting with multichannel VEP recordings, we recommend using a high-frequency hh fVEP in children <3 years of age, standard fVEP in toddlers, and poVEP 60 0 in subjects ‡6 years of age. fVEP can also be used in the oldest age group for subjects with visual acuity of >0.3 logMAR. Remarkably, some albinism subjects showed misrouting on full-field stimulation but normal routing of the central retina, suggesting that not the whole line of decussation is shifted temporally.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Subjectsmentioning

confidence: 99%

mentioning

confidence: 99%

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The Detection Of Misrouting In Albinism: Evaluation of Different VEP Procedures in a Heterogeneous Cohort

Kruijt

Wit

Talsma

et al. 2019

Invest. Ophthalmol. Vis. Sci.

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“…Phenotypical characteristics of foveal hypoplasia (FH) and abnormalities of optic nerve decussation have previously been described in association with albinism and albinism syndromes due to disruption of the melanin biosynthesis pathway ( 1 ). Al-Araimi et al.…”

Section: Introductionmentioning

confidence: 99%

SLC38A8 mutations result in arrested retinal development with loss of cone photoreceptor specialization

Kuht

Han

Maconachie

et al. 2020

Human Molecular Genetics

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FHONDA (foveal hypoplasia, optic nerve decussation defects and anterior segment dysgenesis) is an autosomal recessive disorder arising from SLC38A8 mutations. SLC38A8 is a putative glutamine transporter with strong expression within the photoreceptor layer in the retina. Previous studies have been limited due to lack of quantitative data on retinal development and nystagmus characteristics. In this multi-centre study, custom-targeted next generation sequencing (NGS) gene panel was used to identify SLC38A8 mutations from a cohort of 511 nystagmus patients. We report sixteen novel SLC38A8 mutations. The sixth transmembrane domain is most frequently disrupted by missense SLC38A8 mutations. 90% of our cases were initially misdiagnosed as PAX6-related phenotype or ocular albinism prior to NGS. We characterised the retinal development in vivo in patients with SLC38A8 mutations using high resolution optical coherence tomography. All patients had severe grades of arrested retinal development with lack of a foveal pit and no cone photoreceptor outer segment lengthening. Loss of foveal specialisation features such as outer segment lengthening implies reduced foveal cone density which contributes to reduced visual acuity. Unlike other disorders (such as albinism or PAX6 mutations) which exhibit a spectrum of foveal hypoplasia, SLC38A8 mutations have arrest of retinal development at an earlier stage resulting in a more under-developed retina and severe phenotype.

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Genetic Disorders of Pigmentation

Morice‐Picard,

Taïeb

2024

Rook's Textbook of Dermatology

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Differences in skin and hair colour are principally the result of differences in the melanin content of skin. The synthesis of melanin takes place in melanocytes within specialised vesicles known as melanosomes, then distributed to surrounding keratinocytes. Development of skin pigmentation is a complex multistep process that is tightly regulated. Mutations in genes involved in any one of these steps may lead to pigmentary manifestations. Genetic pigmentary disorders provide a way to improve understanding of the development and the regulation of pigmentation.

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The Phenotypic Spectrum of Albinism

Cited by 96 publications

References 27 publications

The Detection Of Misrouting In Albinism: Evaluation of Different VEP Procedures in a Heterogeneous Cohort

The Detection Of Misrouting In Albinism: Evaluation of Different VEP Procedures in a Heterogeneous Cohort

SLC38A8 mutations result in arrested retinal development with loss of cone photoreceptor specialization

Genetic Disorders of Pigmentation

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