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Phenotypic and genotypic risk factors for uveal melanoma in a high ambient UV radiation environment.

BACKGROUND: Most evidence regarding risk factors for uveal melanoma (UM) derives from case-control studies prone to recall bias, and its rarity has limited prospective research. To address these gaps, we applied a population-based case-control design incorporating polygenic risk scores and Mendelian randomization to explore genetic and phenotypic determinants of UM risk. METHODS: The study was conducted in Queensland, Australia. Incident UM cases diagnosed between 2011 and 2022 were recruited through specialist ocular oncology clinics. Controls were participants in the QSkin Sun and Health Study, a prospective cohort of 43,794 adults aged 40-69 at baseline (2010-2011). Demographic, phenotypic, and sun exposure factors were harmonized across studies. Polygenic risk scores were calculated for pigmentation traits and nevi characteristics using genome-wide association study datasets, and Mendelian randomization was used to assess potential causal relationships with UM risk. RESULTS: Among 485 UM cases and 43,724 controls, several phenotypic traits were strongly associated with UM risk: male sex, blue or light eye color, inability to tan, freckling, and high nevus density. A family history of cutaneous melanoma and a personal history of keratinocyte cancer were also associated with higher risk. Polygenic risk score analyses confirmed significant associations for eye color and freckling. Mendelian randomization analyses supported causal relationships between lighter eye color, freckling propensity, reduced tanning ability and UM risk. CONCLUSIONS: These findings provide genetic evidence supporting a causal role for pigmentation-related traits in UM susceptibility. IMPACT: This evidence may help refine risk assessment and inform counselling for individuals with suspicious ocular lesions.

Journal Article

OCA2 splice site variant in German Spitz dogs with oculocutaneous albinism.

We investigated a German Spitz family where the mating of a black male to a white female had yielded three puppies with an unexpected light brown coat color, lightly pigmented lips and noses, and blue eyes. Combined linkage and homozygosity analysis based on a fully penetrant monogenic autosomal recessive mode of inheritance identified a critical interval of 15 Mb on chromosome 3. We obtained whole genome sequence data from one affected dog, three wolves, and 188 control dogs. Filtering for private variants revealed a single variant with predicted high impact in the critical interval in LOC100855460 (XM_005618224.1:c.377+2T>G LT844587.1:c.-45+2T>G). The variant perfectly co-segregated with the phenotype in the family. We genotyped 181 control dogs with normal pigmentation from diverse breeds including 22 unrelated German Spitz dogs, which were all homozygous wildtype. Comparative sequence analyses revealed that LOC100855460 actually represents the 5'-end of the canine OCA2 gene. The CanFam 3.1 reference genome assembly is incorrect and separates the first two exons from the remaining exons of the OCA2 gene. We amplified a canine OCA2 cDNA fragment by RT-PCR and determined the correct full-length mRNA sequence (LT844587.1). Variants in the OCA2 gene cause oculocutaneous albinism type 2 (OCA2) in humans, pink-eyed dilution in mice, and similar phenotypes in corn snakes, medaka and Mexican cave tetra fish. We therefore conclude that the observed oculocutaneous albinism in German Spitz is most likely caused by the identified variant in the 5'-splice site of the first intron of the canine OCA2 gene.

Albinism, Oculocutaneous

Additional PAX3 Variants for Dominant Blue Eyes in Cats.

Since the recent publication of the first feline variant of the PAX3 (Paired Box 3) gene associated with blue eyes and minimal white spotting (DBE, Dominant Blue Eyes), three further variants of PAX3 have been reported in felines. However, these four variants do not account for all the different feline lines that exhibit DBE. Whole-genome sequencing using short-read and long-read technologies identified a large complex structural variant involving two deletions and an inversion in a purebred line of British shorthair and longhair cats. All 39 British cats with a BDE phenotype were heterozygous for the variant, that was absent in 47 non-DBE cats and 16 DBE cats from other breeding lines. The purebred British shorthair founder female named Nadeya was also heterozygous for the variant, and the segregation of the variant is consistent with dominant inheritance. We named this NC_058375.1:g.[205097674_207411974del;207411975_211290497inv;211290498_211387174del] variant the DBENAD (Nadeya Dominant Blue Eyes) allele. In addition, a candidate gene approach identified a nonsense variant, XM_019838731.3:c.784C>T, in the fifth exon of PAX3 in a second breeding line originating from a female named Marusya. The segregation of this nonsense variant is consistent with dominant inheritance, and a perfect genotype-phenotype correlation was observed in the 16 cats from this line, so we propose that this sixth variant of PAX3 represents the DBEMARU (Marusya Dominant Blue Eyes) allele in the domestic cat. Our study has identified two further variants of the PAX3 gene associated with DBE in domestic cats, which will help to improve genotyping of the breeding stock.

Animals

Clinical characterizations and molecular genetic study of two co-segregating variants in PDZD7 and PDE6C genes leading simultaneously to non-syndromic hearing loss and achromatopsia.

BACKGROUND: Autosomal recessive non-syndromic hearing loss (NSHL) and cone dystrophies (CODs) are highly genetically and phenotypically heterogeneous disorders. In this study, we applied the whole exome sequencing (WES) to find the cause of HL and COD in an Iranian consanguineous family with three affected individuals. METHODS: Three members from an Iranian consanguineous family who were suffering from NSHL and visual impairment were ascertained in this study. Comprehensive clinical evaluations and genetic analysis followed by bioinformatic and co-segregation studies were performed to diagnose the cause of these phenotypes. Data were collected from 2020 to 2022. RESULTS: All cases showed congenital bilateral NSHL, decreased visual acuity, poor color discrimination, photophobia and macular atrophy. Moreover, cornea, iris and anterior vitreous were within normal limit in both eyes, decreased foveal sensitivity, central scotoma and generalized depression of visual field were seen in three cases. WES results showed two variants, a novel null variant (p.Trp548Ter) in the PDE6C gene causing COD type 4 (Achromatopsia) and a previously reported variant (p.Ile84Thr) in the PDZD7 gene causing NSHL. Both variants were found in the cis configuration on chromosome 10 with a genetic distance of about 8.3 cM, leading to their co-inheritance. However, two diseases could appear independently in subsequent generations due to crossover during meiosis. CONCLUSIONS: Here, we could successfully determine the etiology of a seemingly complex phenotype in two adjacent genes. We identified a novel variant in the PDE6C gene, related to achromatopsia. Interestingly, this variant could cooperatively cause visual disorders: cone dystrophy and cone-rod dystrophy.

Adult

Guidance (challenges and priorities) in the assessment of children with low vision: ERN-EYE clinical consensus statement.

Across Europe, children living with low vision often face inconsistent approaches to the assessment of their visual function, leading to delays in diagnosis and unequal access to care. To address this gap, a multidisciplinary group of experts from 8 European countries developed a clinical consensus statement (CCS), using a modified Delphi process. This CCS provides guidance on evaluation of primary visual functions in children with low vision, regardless of etiologies. Assessing visual function can be challenging and cannot be limited to testing visual acuity. It requires a comprehensive approach that takes into account the child's developmental age and necessary adjustments for vision loss. This consensus statement presents different validated tools to evaluate visual acuity, contrast sensitivity, visual field, and color vision. It provides practical guidance for their use across developmental stages, including infancy and in children with syndromic or neurodevelopmental conditions, and highlights the critical role of caregivers in ensuring reliable assessments. The recommendations emphasize the need for age-appropriate testing strategies, tailored adaptations for low vision and additional impairment, and the importance of early assessment to support timely habilitation and optimize developmental outcomes.

Assessment

Conserved function of medaka pink-eyed dilution in melanin synthesis and its divergent transcriptional regulation in gonads among vertebrates.

Medaka is emerging as a model organism for the study of vertebrate development and genetics, and its effectiveness in forward genetics should prove equal to that of zebrafish. Here, we identify by positional cloning a gene responsible for the medaka i-3 albino mutant. i-3 larvae have weakly tyrosinase-positive cells but lack strongly positive and dendritic cells, suggesting loss of fully differentiated melanophores. The region surrounding the i-3 locus is syntenic to human 19p13, but a BAC clone covering the i-3 locus contained orthologs located at 15q11-13, including OCA2 (P). Medaka P consists of 842 amino acids and shares approximately 65% identity with mammalian P proteins. The i-3 mutation is a four-base deletion in exon 13, which causes a frameshift and truncation of the protein. We detected medaka P transcripts in melanin-producing eyeballs and (putative) skin melanophores on embryos and an alternatively spliced form in the non-melanin-producing ovary or oocytes. The mouse p is similarly expressed in gonads, but not alternatively spliced. This is the first isolation of nonmammalian P, the functional mechanism of action of which has not yet been elucidated, even in mammals. Further investigation of the functions of P proteins and the regulation of their expression will provide new insight into body color determination and gene evolution.

Amino Acid Sequence

Aflibercept With Versus Without Reduced-Fluence Photodynamic Therapy for Polypoidal Choroidal Vasculopathy: Optical Coherence Tomography Angiographic Changes From a Randomized Clinical Trial.

OBJECTIVES: To report the longitudinal optical coherence tomography angiography (OCTA) changes in polypoidal choroidal vasculopathy (PCV) treated with intravitreal aflibercept monotherapy or in combination with reduced-fluence PDT. DESIGN: Image analysis of a double-masked, sham-controlled, randomized clinical trial. SUBJECTS: 55 eyes of 55 treatment-na&#xef;ve participants with symptomatic macular PCV completing 52 weeks of follow-up. METHODS: Participants underwent protocolized, multimodal imaging, including OCT, OCTA, fluorescein angiography, and indocyanine green angiography at baseline, week 12, and week 52. Quantitative OCTA parameters included total lesion area, branching neovascular network (BNN) area, and BNN vessel density (VD). Qualitative features included trunk vessel presence and OCTA signal within the polypoidal lesion (PL). Eyes were categorized by treatment arm and PL closure at week 52. MAIN OUTCOME MEASURES: Longitudinal OCTA changes and predictors of PL closure at week 52. RESULTS: We included 55 eyes (28 combination therapy and 27 monotherapy). Total lesion area decreased at week 12 but returned toward baseline at week 52 (combination: 3.72 &#xb1; 3.01mm2 at baseline, 2.86 &#xb1; 2.50mm2 at week 12, 3.59 &#xb1; 3.26mm2 at week 52; monotherapy: 3.77 &#xb1; 2.23mm2 at baseline, 3.27 &#xb1; 2.36mm2 at week 12, and 3.47 &#xb1; 2.58mm2 at week 52). BNN area decreased at week 12 and remained reduced at week 52 in both treatment arms (combination: 2.29 &#xb1; 2.08 mm2 at baseline, 1.46 &#xb1; 1.36mm2 at week 12, and 1.53 &#xb1; 1.32mm2 at week 52; monotherapy: 2.39 &#xb1; 1.85mm2 at baseline, 1.87 &#xb1; 1.68mm2 at week 12, and 1.82 &#xb1; 1.38mm2 at week 52). BNN VD reduction was greater in the combination arm at week 12 (-10 &#xb1; 15% vs - 3 &#xb1; 12%, P = .02). The proportion of eyes with trunk vessels increased over time in both arms (combination: 35.7% at baseline, 59.3% at week 12, and 67.8% at week 52; monotherapy: 25.9% at baseline, 44.4% at week 12, and 71.4% at week 52). In multivariable analysis, baseline BCVA predicted BCVA change at week 52 (&#x3b2;=-0.96 [-1.21 to -0.72], P < .01), and baseline CST predicted CST change (&#x3b2;=0.93 [0.75 to 1.10], P < .01). Greater reduction in BNN VD at week 12 was independently associated with PL closure at week 52 (OR 0.62 [0.39 to 0.97], P = .03). CONCLUSIONS: Early reduction in BNN vessel density, rather than reduction in lesion size, was associated with subsequent PL closure. OCTA-derived vascular changes may serve as noninvasive biomarkers for predicting treatment response in PCV.

Humans