We performed indirect immunofluorescence (IF) studies using 1 mol/l sodium chloride split skin to determine whether or not a positive IF is specific to patients with bullous lupus erythematosus (LE). We examined the sera from 21 patients with systemic LE (SLE), three of which were obtained from two SLE patients and one subacute cutaneous LE (SCLE) patient with bullous eruptions. As a comparison, we also studied the sera from patients with discoid LE (DLE, n = 7), SCLE (n = 1), systemic sclerosis (SSc, n = 20), bullous pemphigoid (n = 2) and normal individuals (n = 10). Sera from 16 SLE, four DLE and two SSc revealed a linear deposition of IgG isotype antibody at the epidermal side and/or the dermal side on indirect IF of split skin. The sera from three patients with bullous eruption and from 12 patients of SLE, SCLE, DLE without bullous eruption or SSc were further analysed by immunoblotting using five defined antigens, i.e. dermal extract, epidermal extract, three fusion proteins of 230 kDa bullous pemphigoid antigen (BPAG). 180 kDa BPAG, and human epidermolysis bullosa acquisita (EBA) antigen. Two SLE sera as well as one of the SCLE and the DLE serum reacted with 230 kDa BPAG in epidermal extract, and one of the SCLE and the DLE serum also reacted with the fusion protein of 180 kDa BPAG. No serum reacted with the dermal extract or the fusion protein of 230 kDa BPAG or EBA antigen. There was no consistent correlation between split-skin IF results and immunoblotting results. These results may suggest that even non-bullous LE patients often have autoantibodies to the basement membrane zone antigens, most of which are less pathogenic. Although we rarely examine the sera from non-bullous LE patients, we should keep this phenomenon in mind to avoid overestimating the results of split-skin test and immunoblotting.

We performed indirect immunofluorescence (IF) studies using 1 mol/l sodium chloride split skin to determine whether or not a positive IF is specific to patients with bullous lupus erythematosus (LE). We examined the sera from 21 patients with systemic LE (SLE), three of which were obtained from two SLE patients and one subacute cutaneous LE (SCLE) patient with bullous eruptions. As a comparison, we also studied the sera from patients with discoid LE (DLE, n = 7), SCLE (n = 1), systemic sclerosis (SSc, n = 20), bullous pemphigoid (n = 2) and normal individuals (n = 10). Sera from 16 SLE, four DLE and two SSc revealed a linear deposition of IgG isotype antibody at the epidermal side and/or the dermal side on indirect IF of split skin. The sera from three patients with bullous eruption and from 12 patients of SLE, SCLE, DLE without bullous eruption or SSc were further analysed by immunoblotting using five defined antigens, i.e. dermal extract, epidermal extract, three fusion proteins of 230 kDa bullous pemphigoid antigen (BPAG). 180 kDa BPAG, and human epidermolysis bullosa acquisita (EBA) antigen. Two SLE sera as well as one of the SCLE and the DLE serum reacted with 230 kDa BPAG in epidermal extract, and one of the SCLE and the DLE serum also reacted with the fusion protein of 180 kDa BPAG. No serum reacted with the dermal extract or the fusion protein of 230 kDa BPAG or EBA antigen. There was no consistent correlation between split-skin IF results and immunoblotting results. These results may suggest that even non-bullous LE patients often have autoantibodies to the basement membrane zone antigens, most of which are less pathogenic. Although we rarely examine the sera from non-bullous LE patients, we should keep this phenomenon in mind to avoid overestimating the results of split-skin test and immunoblotting.

Retinitis pigmentosa 11 (RP11) is caused by dominant mutations in PRPF31, however a significant proportion of mutation carriers do not develop retinopathy. Here, we investigated the relationship between CNOT3 polymorphism, MSR1 repeat copy number and disease penetrance in RP11 patients and non-penetrant carriers (NPCs). We further characterized PRPF31 and CNOT3 expression in fibroblasts from eight RP11 patients and one NPC from a family carrying the c.1205C>T variant. Retinal organoids (ROs) and retinal pigment epithelium (RPE) were differentiated from induced pluripotent stem cells derived from RP11 patients, an NPC and a control subject. All RP11 patients were homozygous for the 3-copy MSR1 repeat in the PRPF31 promoter, while 3/5 NPCs carried a 4-copy MSR1 repeat. The CNOT3 rs4806718 genotype did not correlate with disease penetrance. PRFP31 expression declined with age in adult cadaveric retina. PRPF31 and CNOT3 expression was reduced in RP11 fibroblasts, RO and RPE compared with controls. Both RP11 and NPC RPE displayed shortened primary cilia compared with controls, however a subpopulation of cells with normal cilia lengths was present in NPC RPE monolayers. Our results indicate that RP11 non-penetrance is associated with the inheritance of a 4-copy MSR1 repeat, but not with CNOT3 polymorphisms.

Usher syndrome (USH) is the most common form of deaf-blindness, with an estimated prevalence of 4.4 to 16.6 per 100,000 people worldwide. The most common form of USH is type IIA (USH2A), which is caused by homozygous or compound heterozygous mutations in the USH2A gene and accounts for around half of all USH cases. USH2A patients show moderate to severe hearing loss from birth, with diagnosis of retinitis pigmentosa in the second decade of life and variable vestibular involvement. Although hearing aids or cochlear implants can provide some mitigation of hearing deficits, there are currently no treatments aimed at preventing or restoring vision loss in USH2A patients. In this review, we first provide an overview of the molecular biology of the USH2A gene and its protein isoforms, which include a transmembrane protein (TM usherin) and an extracellular protein (EC usherin). The role of these proteins in the inner ear and retina and their impact on the pathogenesis of USH2A is discussed. We review animal cell-derived and patient cell-derived models currently used in USH2A research and conclude with an overview of potential treatment strategies currently in preclinical development and clinical trials.