Early Onset Neovascular Inflammatory Vitreoretinopathy Due to a De Novo CAPN5 Mutation: Report of a Case

Treatment and Visual Outcomes in Pediatric Patients with Autosomal Dominant Neovascular Inflammatory Vitreoretinopathy: A Cohort Study

BACKGROUND

Autosomal dominant neovascular inflammatory vitreoretinopathy (NIV), formerly called "ADNIV," is a rare autoinflammatory condition mainly of adulthood caused by mutations in calcium-activated calpain-5 protease (CAPN5). Our aim is to report the treatment and visual outcomes of children newly diagnosed with NIV after systemic treatment.

METHODS

We reviewed charts of patients ≤18 years old with CAPN5 gene mutation, ocular findings consistent with NIV, and treated with systemic immunosuppression for a minimum of 6 months. Treatment response was based on ophthalmic examination, ultra-widefield fluorescein-angiography (UWFFA), and optical coherence tomography (OCT).

RESULTS

Eight children (16 eyes) were diagnosed with NIV at a median age of 14 (Range [R] 9-16) years, with a median follow-up of 18 months (R6-20). At diagnosis, one patient had impaired visual acuity (VA > 0.4), eight had vascular leakage, two had neovascularization, and three had macular edema. All responded to oral or local glucocorticoids but was not sustained. Systemic immunosuppression was started in seven patients with methotrexate and infliximab after a median time from diagnosis of 1.5 months (R0.5-2) and 3.2 months (R2.5-3.1), respectively. Infliximab was discontinued in all after a median time of 7 months (R3.5-10) for ineffectiveness, and 5/7 switched to tocilizumab and 1 to adalimumab. Five failed to respond (4 tocilizumab, 1 adalimumab) and one had a minimal response to tocilizumab.

CONCLUSIONS

We report on the systemic treatment response of seven children with ADNIV treated with methotrexate, infliximab, and tocilizumab. None were able to control disease. Further studies are needed to understand long-term outcomes and the utility of systemic immunosuppression.

Autosomal dominant neovascular inflammatory vitreoretinopathy with CAPN5 c.731T > C gene mutation; clinical management of a family cohort and review of the literature

BACKGROUND

To report a cohort of patients with clinically and genetically diagnosed autosomal dominant neovascular inflammatory vitreoretinopathy (ADNIV) and showcase the spectrum of the disease utilizing multimodal imaging and genetic testing. Additionally, the utility of multimodal imaging in guiding treatment will also be illustrated.

MATERIALS/METHODS

Five patients from a single-family pedigree in Ohio with clinical signs of ADNIV were evaluated. Medical history, family history, and complete ocular examinations were obtained during regular clinic visits. Multimodal imaging including ocular coherence tomography, fluorescein angiography, wide-field fundus photographs, and Humphrey visual field testing was obtained for all five patients. Additionally, genetic testing for the Calpain-5 (CAPN5) gene was conducted on all patients.

RESULTS

All five patients were noted to have a CAPN5 c.731T > C (p.L244P) mutation on genetic testing. Using multimodal imaging to supplement the clinical examination, pathologic changes such as retinal vascular inflammation, macular edema, and tractional retinal membranes were well illustrated and monitored over time. This allowed for earlier intervention when appropriate such as with intraocular steroid or systemic anti-inflammatory treatments.

CONCLUSION

Phenotypic presentation varied among patients in this series, but is consistent with the spectrum of pathologic changes previously described in patients with other CAPN5 gene mutations. Monitoring of patients with ADNIV utilizing multimodal imaging can help better assess progression of this disease and guide treatment decisions. Additionally, increased genetic testing in patients with inherited retinal diseases may reveal novel gene mutations that could serve as potential targets for future genetic treatment regimens.

Early-onset Neovascular Inflammatory Vitreoretinopathy Due to Two de Novo CAPN5 Mutations in Chinese Patients: A Case Series

PURPOSE

To explore the clinical and molecular characteristics, diagnosis, and treatment of early-onset autosomal dominant neovascular inflammatory vitreoretinopathy (ADNIV) in Chinese patients.

METHODS

A retrospective, interventional case series was assembled from three ADNIV patients.

RESULTS

The three ADNIV cases harbored de novo CAPN5 mutations (p.Arg289Trp and p.Leu73Val). The ages of onset ranged from 11 months to 2 years. All the cases presented with vitreous opacity and subretinal inflammatory exudations. During the postoperative follow-up, all the patients manifested with exaggerated postoperative inflammatory responses. An intravitreal Ozurdex injection could not effectively control ocular inflammation in ADNIV. Laser spots after panretinal photocoagulation were partly visible.

CONCLUSIONS

Two de novo CAPN5 mutations (p.Leu73Val and p.Arg289Trp) could cause early-onset ADNIV. Panretinal photocoagulation during vitrectomy and an intravitreal Ozurdex injection could not significantly stop the progression of subretinal exudations and ocular inflammation in early-onset ADNIV patients.

Impaired activity and membrane association of most calpain-5 mutants causal for neovascular inflammatory vitreoretinopathy

Neovascular inflammatory vitreoretinopathy (NIV) is a rare eye disease that ultimately leads to complete blindness and is caused by mutations in the gene encoding calpain-5 (CAPN5), with six pathogenic mutations identified. In transfected SH-SY5Y cells, five of the mutations resulted in decreased membrane association, diminished S-acylation, and reduced calcium-induced autoproteolysis of CAPN5. CAPN5 proteolysis of the autoimmune regulator AIRE was impacted by several NIV mutations. R243, L244, K250 and the adjacent V249 are on β-strands in the protease core 2 domain. Conformational changes induced by Ca2+binding result in these β-strands forming a β-sheet and a hydrophobic pocket which docks W286 side chain away from the catalytic cleft, enabling calpain activation based on comparison with the Ca2+-bound CAPN1 protease core. The pathologic variants R243L, L244P, K250N, and R289W are predicted to disrupt the β-strands, β-sheet, and hydrophobic pocket, impairing calpain activation. The mechanism by which these variants impair membrane association is unclear. G376S impacts a conserved residue in the CBSW domain and is predicted to disrupt a loop containing acidic residues which may contribute to membrane binding. G267S did not impair membrane association and resulted in a slight but significant increase in autoproteolytic and proteolytic activity. However, G267S is also identified in individuals without NIV. Combined with the autosomal dominant pattern of NIV inheritance and evidence that CAPN5 may dimerize, the results are consistent with a dominant negative mechanism for the five pathogenic variants which resulted in impaired CAPN5 activity and membrane association and a gain-of-function for the G267S variant.

Long-Term Outcomes and Risk Factors for Severe Vision Loss in Autosomal Dominant Neovascular Inflammatory Vitreoretinopathy (ADNIV)

Autosomal dominant neovascular inflammatory vitreoretinopathy (ADNIV) is a rare disorder characterized by uveitis, retinal neovascularization, and retinal degeneration. We sought to describe the course of treated and untreated ADNIV and to identify risk factors for severe vision loss.

DESIGN

Observational case series.

METHODS

Clinical data from ADNIV patients from 4 families seen from 1967 through 2019 at a single academic, tertiary referral center were reviewed. The main outcome measures were visual acuity at baseline and follow-up, as well as risk factors for vision loss.

RESULTS

A total of 130 eyes from 65 ADNIV patients (45 female, 20 male; mean age 40.8 years, range 6-77 years) were included. Mean best corrected visual acuity (BCVA) at presentation was LogMAR 0.59 (about Snellen 20/80). Longitudinal analysis included 84 eyes from 42 patients (31 female, 11 male), with mean follow-up of 17.3 years (range 2-43.6 years). Mean BCVA at last follow-up was LogMAR 1.48 (about Snellen 20/600). The disease accelerated in the fifth decade of life, during which the majority of eyes went from normal vision or mild vision loss to at least moderate vision loss (20/70 Snellen equivalent); 25 eyes from 16 patients (29.8%;) showed a steep trajectory of vision loss to no light perception. Tractional retinal detachment was the greatest risk factor for severe vision loss (BCVA <20/200) on multivariable analysis (P < .05).

CONCLUSIONS

Patients with ADNIV have a high lifetime risk of severe vision loss. Tractional retinal detachment is an important risk factor for poor vision.

Variable expressivity of BEST1-associated autosomal dominant vitreoretinochoroidopathy (ADVIRC) in a three-generation pedigree

Objective

Autosomal dominant vitreoretinochoroidopathy (ADVIRC) is associated with pathogenic variants in BEST1, which typically causes visual impairment in the late stage of disease. We present a pedigree with variable expressivity and the youngest case in the literature with visual impairment in early childhood.

Methods and analysis

This is a retrospective, observational, case series describing multigenerational members of one family affected with ADVIRC. Patients underwent examination, ultra-widefield fundus photography and angiography, optical coherence tomography, full-field electroretinography (ffERG) and full-field perimetry.

Results

Three affected members of the pedigree, one from each successive generation, were found to harbour a mutation, c.715G>A:p.Val239Met, in BEST1. The proband characterised in this report is, to our knowledge, the youngest documented case of ADVIRC in early childhood. Yet, this patient has the most severe retinal dysfunction compared with the father and paternal grandmother, whom exhibit classic characteristics of ADVIRC. Longitudinal data from the paternal grandmother showed that there was a rapid decline in ffERG responses (photopic decline worse than scotopic) from the fourth to fifth decade of life, which correlated with severe concentric constriction of visual fields.

Conclusion

This multigenerational case series provides new insights into the ADVIRC disease spectrum and rate of progression. While ADVIRC typically causes a slowly progressive disease, we show that variable phenotypic expressivity is possible among affected members of the same family with the same mutation in BEST1. Thus, ADVIRC must also be considered in the differential diagnosis of paediatric patients with severe retinal dystrophy in early childhood.

Structural Insights into the Unique Activation Mechanisms of a Non-classical Calpain and Its Disease-Causing Variants

Increased calpain activity is linked to neuroinflammation including a heritable retinal disease caused by hyper-activating mutations in the calcium-activated calpain-5 (CAPN5) protease. Although structures for classical calpains are known, the structure of CAPN5, a non-classical calpain, remains undetermined. Here we report the 2.8 Å crystal structure of the human CAPN5 protease core (CAPN5-PC). Compared to classical calpains, CAPN5-PC requires high calcium concentrations for maximal activity. Structure-based phylogenetic analysis and multiple sequence alignment reveal that CAPN5-PC contains three elongated flexible loops compared to its classical counterparts. The presence of a disease-causing mutation (c.799G>A, p.Gly267Ser) on the unique PC2L2 loop reveals a function in this region for regulating enzymatic activity. This mechanism could be transferred to distant calpains, using synthetic calpain hybrids, suggesting an evolutionary mechanism for fine-tuning calpain function by modifying flexible loops. Further, the open (inactive) conformation of CAPN5-PC provides structural insight into CAPN5-specific residues that can guide inhibitor design.