Non-exudative macular neovascularization in pseudoxanthoma elasticum

Pseudoxanthoma elasticum - Genetics, pathophysiology, and clinical presentation

Pseudoxanthoma elasticum (PXE) is an autosomal-recessively inherited multisystem disease. Mutations in the ABCC6-gene are causative, coding for a transmembrane transporter mainly expressed in hepatocytes, which promotes the efflux of adenosine triphosphate (ATP). This results in low levels of plasma inorganic pyrophosphate (PPi), a critical anti-mineralization factor. The clinical phenotype of PXE is characterized by the effects of elastic fiber calcification in the skin, the cardiovascular system, and the eyes. In the eyes, calcification of Bruch's membrane results in clinically visible lesions, including peau d'orange, angioid streaks, and comet tail lesions. Frequently, patients must be treated for secondary macular neovascularization. No effective therapy is available for treating the cause of PXE, but several promising approaches are emerging. Finding appropriate outcome measures remains a significant challenge for clinical trials in this slowly progressive disease. This review article provides an in-depth summary of the current understanding of PXE and its multi-systemic manifestations. The article offers a detailed overview of the ocular manifestations, including their morphological and functional consequences, as well as potential complications. Lastly, previous and future clinical trials of causative treatments for PXE are discussed.

Prevalence, Features, and Outcomes of Type 1 Neovascularization in Eyes with Angioid Streaks

PURPOSE

This study aimed to delineate the characteristics, prevalence, and outcomes of neovascularization (NV), particularly aneurysmal type 1 NV, in patients with angioid streaks (AS) secondary to pseudoxanthoma elasticum (PXE), and to introduce a clinical classification based on multimodal imaging.

DESIGN

Retrospective longitudinal cohort study.

PARTICIPANTS

Eighty-five patients (168 eyes) with AS secondary to PXE at 2 tertiary referral centers.

METHODS

Data collection included demographic, medical, and ocular histories. Diagnostic methods comprised fundus photography, autofluorescence, indocyanine green angiography, OCT, and OCT angiography.

MAIN OUTCOME MEASURES

Prevalence of type 1 NV, visual acuity (VA), risk of exudation.

RESULTS

Type 1 NV was identified in 127 eyes (76%), with 85 of these (67%) showing exclusively type 1 NV. These lesions often originated around the disc, at sites of Bruch membrane dehiscences, and followed the path of AS, extending to the macula in 101 eyes (80%). Despite 65% of type 1 NV remaining nonexudative, 35% evolved into exudative over 5 years, and 11 eyes experienced midperipheral subretinal hemorrhages. Aneurysmal dilations, observed in 57% of eyes, substantially increased exudation risk (hazard ratio = 3.86, P = 0.02). Despite treatment, VA significantly deteriorated in exudative type 1 NV (P = 0.02). Type 2 NV, detected in 42 eyes (33%), often coexisted with type 1 NV and was associated with poorer visual outcomes and higher rates of macular atrophy. A classification of AS was developed, ranging from empty AS (stage 0, no NV) to advanced NV (stage 3, both type 1 and type 2 NV).

CONCLUSIONS

Type 1 NV predominates in AS. Although predominantly nonexudative, its progression correlates with substantial visual impairment, similar to the deficits observed with type 2 NV. Aneurysmal type 1 NV poses a significant exudation risk, underscoring the need for vigilant monitoring.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Comprehensive analysis of pseudoxanthoma elasticum: epidemiological, genetic, and clinical findings from the leading Italian center

BACKGROUND

Pseudoxanthoma elasticum (PXE) is a rare genetic autosomal recessive metabolic disease characterized by progressive mineralization and fragmentation of elastic fibers from soft connective tissues. The objective of our study was to analyze the epidemiological, genetic, cutaneous, and extracutaneous clinical data from the largest Italian monocentric cohort of PXE patients.

METHODS

We included all patients diagnosed with PXE and referred to Neurocutaneous Rare Diseases at Umberto I Polyclinic Hospital (Rome, Italy) between January 1983 and February 2024. A retrospective analysis of their data was performed.

RESULTS

We enrolled 86 patients (77.9% women), revealing compound heterozygosity in 19.8% of cases and homozygosity in 5.8%. Missense (34.9%), non-sense (5.8%), splice-site (5.8%), deletion (4.7%), and frameshift (2.3%) mutations were disclosed. Cutaneous alterations were noted in the neck (69.7%), axilla (33.7%), inguinal (17.5%), and cubital folds (11.7%). The most common ocular findings were angioid streaks (64.0%) and choroidal neovascularization (18.6%), with blindness reported in 5.8% of cases. Thicker intima-media was observed around the mid-fifties in the supra-aortic trunks (40.7%), lower limb arteries (32.6%), and renal arteries (4.7%). Regurgitation was more common in atrioventricular valves (48.8%) than in semilunar ones (10.5% and 9.3%). Dyslipidemia (19.8%), hypertension (18.8%), and fatty liver disease (12.8%) were prevalent, with calcifications found in the kidneys (25.6%), liver (15.1%), spleen (11.6%), and testicles (8.1% of males). Autoimmune diseases and depression were observed in 11.6% and 4.7% of cases, respectively.

CONCLUSIONS

Enhanced understanding of PXE can improve patients' quality of life and facilitate the development of more effective therapeutic strategies.

Long-term functional, anatomical outcome, and qualitative analysis by OCTA, as a predictor of disease recurrences in patients with choroidal neovascularization secondary to angioid streaks

BACKGROUND

To report the risk of exudation recurrence and long-term outcomes in patients with choroidal neovascularization secondary to angioid streaks, according to its morphology and characteristics by optical coherence tomography angiography.

METHODS

Retrospective analysis of electronic medical records from three hospitals. We enrolled patients with a clinical diagnosis of angioid streaks choroidal neovascularization that had a minimum follow-up of 12 months. From each record, we extracted general demographic data, best corrected visual acuity (baseline, before and after each disease recurrence and last on file), type of treatment, time between last intravitreal injection and disease recurrence, and classification of the neovascular lesion morphology by optical coherence tomography, and optical coherence tomography angiography. Patients with myopic choroidal neovascularization were used as controls. Interobserver agreement was assessed with a Cohen-Kappa test. The Odds ratio was calculated with a chi2 test for significance. Visual acuity change through time was evaluated with an ANOVA for repeated measurements with an alpha value of 0.05 for statistical significance.

RESULTS

We enrolled 30 patients in the study group and 14 in the control group. In the study group, the baseline and final BCVA were 0.861 ± 0.59 and 1.095 ± 0.61 logMAR (p = 0.1) respectively.

CONTROL GROUP

1.045 ± 0.57 and 0.617 ± 0.53 logMAR (p < 0.05). In the study group, the predominant CNV type by OCTA was mixed (37%), and interlacing (57%) in the control group. Mixed and cog-wheel patterns at baseline had increased Odds for recurrence in the study group (p = 0.09). Patients in the study group required more intravitreal injections on each recurrence episode to achieve disease control (3.5 ± 1.5 vs.1.4 ± 0.2, p < 0.01).

CONCLUSIONS

The benefits of anti-VEGF treatment are lost over time in patients with angioid streaks and CNV. Lesion characteristics by optical coherence tomography angiography could help physicians predict the risk of recurrence.

TRIAL REGISTRATION

Retrospective registered, and IRB approved.

EXTENSIVE SUBRETINAL FIBROSIS ASSOCIATED WITH PSEUDOXANTHOMA ELASTICUM

PURPOSE

The purpose of this study was to report an unusual case of pseudoxanthoma elasticum presenting with an inflammatory phenotype associated with atypical and rapidly progressive subretinal fibrosis.

METHODS

This was an observational case report.

RESULTS

A patient with a history of pseudoxanthoma elasticum presented with rapidly progressive subretinal fibrosis, particularly in the left eye, over the course of one year. The patient was noted at presentation to have intraocular inflammation, outer retinal attenuation, multifocal choroiditis-like lesions, and intraretinal fluid (in the absence of obvious clinical or angiographic signs of exudative choroidal neovascular membranes). An ocular inflammatory phenotype was diagnosed, and the patient was treated with a combination of local steroids and systemic corticosteroids/immunomodulatory agents. After initiation of these agents, the patient demonstrated functional and structural improvement, with partial outer retinal reconstitution, decreased intraretinal fluid, and lack of further progression of subretinal fibrosis.

CONCLUSION

This report describes an inflammatory phenotype of pseudoxanthoma elasticum associated with severe and atypical subretinal fibrosis. This case expands upon the currently known spectrum of inflammatory phenotypes associated with pseudoxanthoma elasticum. Treatment with corticosteroids or immunomodulatory treatment should be considered in similar cases.

Mutational spectrum and deep phenotyping in Pseudoxanthoma Elasticum: Findings from a Portuguese cohort

INTRODUCTION

Pseudoxanthoma Elasticum (PXE) is a rare autosomal recessive disorder originated by disease-causing variants in ABCC6 gene. The purpose of this study was to characterize the genetic landscape, phenotypic spectrum and genotype-phenotype correlations in a Portuguese cohort of PXE patients.

METHODS

Multicentric cross-sectional study conducted in patients with a clinical and genetic diagnosis of PXE. Patients were identified using the IRD-PT registry (www.retina.com.pt). Genotypes were classified into 3 groups: (1) two truncating variants, (2) two non-truncating variants, or (3) mixed variants. Deep phenotyping comprised a comprehensive ophthalmologic and systemic evaluation using the updated Phenodex Score (PS).

RESULTS

Twenty-seven patients (23 families) were included. Sixteen different ABCC6 variants were identified, 7 of which are novel. The most prevalent variant was the nonsense variant c.3421C > T p.(Arg1141*) with an allele frequency of 18.5%. All patients exhibited ocular manifestations. Cutaneous manifestations were present in most patients (88.9%, n = 24/27). A PS score > E2 was strongly associated with worse visual acuity (B = -29.02; p = 0.001). No association was found between genotypic groups and cutaneous, vascular or cardiac manifestations.

CONCLUSIONS

This study describes the genetic spectrum of patients with PXE for the first time in a Portuguese cohort. A total of 16 different variants in ABCC6 were found (7 of which are novel), thus highlighting the genotypic heterogeneity associated with this condition and expanding its mutational spectrum. Still, no major genotype-phenotype associations could be established.

Towards a better understanding of non-exudative choroidal and macular neovascularization

Non-exudative macular and choroidal neovascularization (MNV and CNV) usually refers to the entity of treatment-naïve type 1 neovascularization in the absence of associated signs of exudation. Histopathological studies, dating back in the early 70s, identified the presence of non-exudative MNV, but the first clinical report of this finding was in the late 90s using indocyanine green angiography in eyes with age-related macular degeneration (AMD). With more advanced retinal imaging, there has been an ever increasing appreciation of non-exudative MNV associated with AMD and CNV with other macular disorders. However, consensus regarding the exact definition and the clinical management of this entity is lacking. Furthermore, there may be variation in the imaging features and clinical course suggesting that a spectrum of disease may exist. Herein, we review the large body of published work that has provided a better understanding of non-exudative MNV and CNV in the last decade. The prevalence, multimodal imaging features, clinical course, and response to treatment are discussed to elucidate further key insights about this entity. Based on these observations, this review also proposes a new theory about the origin and course of different sub-types of non-exudative MNV/CNV which can have different etiologies and pathways according to the clinical context of disease.

A case of angioid streaks that produced choroidal neovascularization after the onset of unilateral acute retinopathy in pseudoxanthoma elasticum

Purpose

Observations

Conclusions and importance