High-temperature requirement A1 (HtrA1) has been identified as a disease-susceptibility gene for age-related macular degeneration (AMD) including polypoidal choroidal neovasculopathy (PCV). We characterized the underlying phenotypic changes of transgenic (Tg) mice expressing ubiquitous CAG promoter (CAG-HtrA1 Tg). In vivo imaging modalities and histopathology were performed to investigate the possible neovascularization, drusen formation, and infiltration of macrophages. Subretinal white material deposition and scattered white-yellowish retinal foci were detected on CFP [(Tg—33% (20/60) and wild-type (WT)—7% (1/15), p < 0.05]. In 40% (4/10) of the CAG-HtrA1 Tg retina, ICGA showed punctate hyperfluorescent spots. There was no leakage on FFA and OCTA failed to confirm vascular flow signals from the subretinal materials. Increased macrophages and RPE cell migrations were noted from histopathological sections. Monocyte subpopulations were increased in peripheral blood in the CAG-HtrA1 Tg mice (p < 0.05). Laser induced CNV in the CAG-HtrA1 Tg mice and showed increased leakage from CNV compared to WT mice (p < 0.05). Finally, choroidal explants of the old CAG-HtrA1 Tg mice demonstrated an increased area of sprouting (p < 0.05). Signs of subclinical inflammation was observed in CAG-HtrA1 Tg mice. Such subclinical inflammation may have resulted in increased RPE cell activation and angiogenic potential.

The U4 small nuclear RNA (snRNA) forms a duplex with the U6 snRNA and, together with U5 and ∼30 proteins, is part of the U4/U6.U5 tri-snRNP complex, located at the core of the major spliceosome. Recently, recurrent de novo variants in the U4 RNA, transcribed from the RNU4-2 gene, and in at least two other RNU genes were discovered to cause neurodevelopmental disorder. We detected inherited and de novo heterozygous variants in RNU4-2 (n.18_19insA and n.56T>C) and in four out of the five RNU6 paralogues (n.55_56insG and n.56_57insG) in 135 individuals from 62 families with non-syndromic retinitis pigmentosa (RP), a rare form of hereditary blindness. We show that these variants are recurrent among RP families and invariably cluster in close proximity within the three-way junction (between stem-I, the 5’ stem-loop and stem-II) of the U4/U6 duplex, affecting its natural conformation. Interestingly, this region binds to numerous splicing factors of the tri-snRNP complex including PRPF3, PRPF8 and PRPF31, previously associated with RP as well. The U4 and U6 variants identified seem to affect snRNP biogenesis, namely the U4/U6 di-snRNP, which is an assembly intermediate of the tri-snRNP. Based on the number of positive cases observed, deleterious variants in RNU4-2 and in RNU6 paralogues could be a significant cause of isolated or dominant RP, accounting for up to 1.2% of all undiagnosed RP cases. This study highlights the role of non-coding genes in rare Mendelian disorders and uncovers pleiotropy in RNU4-2 , where different variants underlie neurodevelopmental disorder and RP.

Childhood glaucoma, a significant cause of global blindness, represents a heterogeneous group of disorders categorized into primary or secondary forms. Primary childhood glaucoma stands as the most prevalent subtype, comprising primary congenital glaucoma (PCG) and juvenile open-angle glaucoma (JOAG). Presently, multiple genes are implicated in inherited forms of primary childhood glaucoma. This comprehensive review delves into genetic investigations into primary childhood glaucoma, with a focus on identifying causative genes, understanding their inheritance patterns, exploring essential biological pathways in disease pathogenesis, and utilizing animal models to study these mechanisms. Specifically, attention is directed towards genes such as CYP1B1 (cytochrome P450 family 1 subfamily B member 1), LTBP2 (latent transforming growth factor beta binding protein 2), TEK (TEK receptor tyrosine kinase), ANGPT1 (angiopoietin 1), and FOXC1 (forkhead box C1), all associated with PCG; and MYOC (myocilin), associated with JOAG. Through exploring these genetic factors, this review aims to deepen our understanding of the intricate pathogenesis of primary childhood glaucoma, thereby facilitating the development of enhanced diagnostic and therapeutic strategies.

Retinal biopsies are rarely feasible, limiting direct studies of inherited retinal dystrophies (IRDs). We present a protocol modeling occult macular dystrophy, an autosomal-dominant IRD, using induced pluripotent stem cells (iPSCs) generated from patient blood cells. We describe steps to differentiate iPSCs into photoreceptor-like cells by transducing CRX and NEUROD1 via a tetracycline-inducible PiggyBac vector. We also detail procedures for the validation of photoreceptor markers to assess differentiation. This protocol enables mutation-focused investigation of IRD pathogenesis. For complete details on the use and execution of this protocol, please refer to Pan et al.¹.