Autoimmune retinopathy in a patient with autoimmune polyendocrine syndrome type I

Retinopathy as an initial sign of hereditary immunological diseases: report of six families and challenges in eye clinic

Introduction

Retinal degenerative or inflammatory changes may occur with hereditary immunological disorders (HID) due to variants in approximately 20 genes. This study aimed to investigate if such retinopathy may present as an initial sign of immunological disorders in eye clinic.

Methods

The variants in the 20 genes were selected from in-house exome sequencing data from 10,530 individuals with different eye conditions. Potential pathogenic variants were assessed by multistep bioinformatic analysis. Pathogenic variants were defined according to the ACMG/AMP criteria and confirmed by Sanger sequencing, co-segregation analysis, and consistency with related phenotypes. Ocular clinical data were thoroughly reviewed, especially fundus changes.

Results

A total of seven pathogenic variants in four of the 20 genes were detected in six probands from six families, including three with hemizygous nonsense variants p.(Q308*), p.(Q416*), and p.(R550*) in MSN, one with homozygous nonsense variants p.(R257*) in AIRE, one with compound heterozygous nonsense variants p.(R176*) and p.(T902*) in LAMB2, and one with a known c.1222T>C (p.W408R) heterozygous variant in CBL. Ocular presentation, as the initial signs of the diseases, was mainly retinopathy mimicking other forms of hereditary retinal degeneration, including exudative vitreoretinopathy in the three patients with MSN variants or tapetoretinal degeneration in the other three patients. Neither extraocular symptoms nor extraocular manifestations were recorded at the time of visit to our eye clinic. However, of the 19 families in the literature with retinopathy caused by variants in these four genes, only one family with an AIRE homozygous variant had retinopathy as an initial symptom, while the other 18 families had systemic abnormalities that preceded retinopathy.

Discussion

This study, for the first time, identified six unrelated patients with retinopathy as their initial and only presenting sign of HID, contrary to the previous reports where retinopathy was the accompanying sign of systemic HID. Recognizing such phenotype of HID may facilitate the clinical care of these patients. Follow-up visits to such patients and additional studies are expected to validate and confirm our findings.

Cone dystrophy associated with autoimmune polyglandular syndrome type 1

To report the association of autoimmune polyglandular syndrome type 1 (APS1) with cone dystrophy in a large Saudi family. This is a Retrospective chart review and prospective genetic testing and ophthalmic examination of a large multiplex consanguineous family. Genetic testing was performed on 14 family members, seven of whom had detailed ophthalmic examinations. Medical history, ocular history and evaluation, visual field testing, full-field electroretinogram (ERG), and Whole Exome Sequencing (WES) results were analyzed. Three family members were homozygous for c.205_208dupCAGG;p.(Asp70Alafs*148) in AIRE and homozygous for c.481-1G>A in PDE6C. One additional family member was homozygous for only the AIRE variant and another additional family member was homozygous for only the PDE6C variant. All patients with homozygosity for the PDE6C variant had cone dystrophy, and all patients with homozygosity for the AIRE variant had APS1. In addition, two of the family members who were homozygous for the PDE6C and AIRE variants had reduced rod function on ERG. We report the co-inheritance for APS1 and PDE6C-related cone dystrophy, an unusual example of two seemingly independent recessive conditions coinciding within a family. Dual molecular diagnosis must be taken into account by ophthalmologists facing unusual constellations of findings, especially in consanguineous families.

Detection of circulating anti-retinal antibodies in dogs with sudden acquired retinal degeneration syndrome using indirect immunofluorescence: A case-control study

Sudden acquired retinal degeneration syndrome (SARDS) in dogs is proposed to have an immune-mediated etiology. However, there is conflicting evidence regarding the presence of antiretinal antibodies, as assessed by western blotting, in the serum of SARDS patients. Because of the possibility that antibodies recognize only conformational epitopes, we hypothesized that a more sensitive method to investigate circulating retinal autoantibodies in SARDS is immunofluorescence. Sera from 14 dogs with early SARDS, and 14 age- and breed-matched healthy control dogs were screened for circulating antiretinal IgG, IgM, IgE and IgA using indirect immunofluorescence on lightly fixed frozen sections of normal canine retina. Controls without canine serum were also performed. A nuclear counterstain was used to identify cellular retinal layers. Images were obtained using a fluorescence microscope, and 2-3 separate masked observers graded retinal layers for fluorescence staining intensity using a 0-3 scale. Total circulating IgG and IgM was assessed by radial immunodiffusion. Statistical analysis was performed using 2-way ANOVA, paired 2-tailed student's t-test and correlation analysis. Intensity of IgG staining of photoreceptor outer segments was significantly higher using serum from dogs with SARDS compared with healthy controls in 2/3 observers (P < 0.05). Intensity of IgM staining throughout the retina was higher in SARDS dogs compared to matched healthy controls (P < 0.0001), although no specific retinal layer was statistically significant. There were no differences in staining intensity for IgE or IgA. Dogs with SARDS had a comparably lower circulating IgG and higher IgM than healthy controls (P = 0.01 and 0.001 respectively) and IgG and IgM were negatively correlated (r = -0.69, P = 0.007). Despite having decreased serum IgG compared with healthy controls, circulating IgG in dogs with SARDS binds photoreceptor outer segments to a greater extent. Dogs with SARDS have a relatively higher circulating IgM than matched healthy controls. The pathogenic nature of these antibodies is unknown.

Lymphopenia-induced proliferation in aire-deficient mice helps to explain their autoimmunity and differences from human patients

Studies on autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) and its mouse model – both caused by mutant AIRE – have greatly advanced the understanding of thymic processes that generate a self-tolerant T-cell repertoire. Much is now known about the molecular mechanisms by which AIRE induces tissue-specific antigen expression in thymic epithelium, and how this leads to negative selection of auto-reactive thymocytes. However, we still do not understand the processes that lead to the activation of any infrequent naïve auto-reactive T-cells exported by AIRE-deficient thymi. Also, the striking phenotypic differences between APECED and its mouse models have puzzled researchers for years. The aim of this review is to suggest explanations for some of these unanswered questions, based on a fresh view of published experiments. We review evidence that auto-reactive T-cells can be activated by the prolonged neonatal lymphopenia that naturally develops in young Aire-deficient mice due to delayed export of mature thymocytes. Lymphopenia-induced proliferation (LIP) helps to fill the empty space; by favoring auto-reactive T-cells, it also leads to lymphocyte infiltration in the same tissues as in day 3 thymectomized animals. The LIP becomes uncontrolled when loss of Aire is combined with defects in genes responsible for anergy induction and Treg responsiveness, or in signaling from the T-cell receptor and homeostatic cytokines. In APECED patients, LIP is much less likely to be involved in activation of naïve auto-reactive T-cells, as humans are born with a more mature immune system than in neonatal mice. We suggest that human AIRE-deficiency presents with different phenotypes because of additional precipitating factors that compound the defective negative selection of potentially autoaggressive tissue-specific thymocytes.