Clinical and Molecular Aspects of C2orf71/PCARE in Retinal Diseases

PCARE-Associated Retinopathy - Genetics, Clinical Characteristics, and Natural History

Purpose

The purpose of this study was to describe the mutational landscape, clinical characteristics, and natural history of PCARE-associated retinopathy.

Methods

Retrospective cohort study including 28 patients (56 eyes) affected by an inherited retinal disease related to PCARE variants. The main outcome measures were best-corrected visual acuity (BCVA) and degree of vision impairment, kinetic visual field (KVF) area delimited with the V4e target, area of macular atrophy (MA) with definitely decreased autofluorescence (DDAF) on short-wavelength autofluorescence, total macular volume (TMV) and foveal sparing (FS) on optical coherence tomography.

Results

The median age at first examination was 40.7 years (Interquartile range [IQR] = 28.8-49.6), whereas the median follow-up time was 5.7 years (IQR = 3.6-7.1). The retinal phenotype was consistent with a severe generalized photoreceptor dystrophy with MA in all patients. DDAF lesions were observed in 85% of the eyes. Loss of FS (occurring at a median age of 45 years) was associated with a mean BCVA (logMAR) worsening by 1.1 (95% confidence interval [CI] = 0.6 to 1.5, P < 0.001). Low vision and blindness in the better-seeing eye occurred at median ages of 50 and 57 years, respectively. Longitudinal analysis revealed the following mean slopes of change: BCVA (logMAR) worsened by 0.06/year (95% CI = 0.03 to 0.09, P < 0.001), KVF area decreased by -23%/year (95% CI = -35% to -12%, P = 0.004), square root-transformed DDAF area expanded by 0.20 mm/year (95% CI = 0.16 to 0.23, P < 0.001), and TMV declined by -0.015 mm3/year (95% CI = -0.023 to -0.007, P = 0.003). Eleven novel PCARE variants were identified.

Conclusions

PCARE-associated retinopathy is a severe generalized photoreceptor dystrophy with MA. Although visual field loss occurs early, useful central vision is often retained into late adulthood because of FS. Based on the age of onset of legal blindness, the optimal therapeutic window appears to be before the fifth decade of life.

Mutational Profile and Retinal Phenotypes of PCARE-Related Cone-Rod Dystrophies in a Mexican Cohort

Purpose

The aim of the study is to describe the genotype and phenotype of a Mexican cohort with PCARE-related retinal disease.

Methods

The study included 14 patients from 11 unrelated pedigrees with retinal dystrophies who were demonstrated to carry biallelic pathogenic variants in PCARE. Visual assessment methods included best corrected visual acuity, color fundus photography, Goldmann visual field test, kinetic perimetry, dark/light adapted chromatic perimetry, full-field electroretinography, autofluorescence imaging, and spectral domain-optical coherence tomography imaging. Genetic screening was performed either by gene panel sequencing or by exome sequencing.

Results

According to the results of multimodal imaging and functional tests, all 14 patients were diagnosed with cone-rod dystrophy. Six different PCARE pathogenic alleles were identified in our cohort, including three novel mutations: c.3048_3049del (p.Tyr1016∗), c.3314_3315del (p.Ser1105∗), and c.551A > G (p.His184Arg). Notably, alleles p.His184Arg, p.Arg613∗, and p.Arg984∗ were present in 18 of the 22 (82%) PCARE alleles from probands in our cohort.

Conclusion

Our work expands the PCARE mutational profile by identifying three novel pathogenic variants causing retinal dystrophy. While phenotypic variations occurred among patients, a cone-rod dystrophy pattern was observed in all affected individuals.

Special Issue "The Molecular and Cellular Pathophysiologic Mechanisms Underlying Ocular Diseases and Emerging Therapies"

Visual impairment and ophthalmic diseases represent significant global public health concerns, and their prevalence continues to rise [...].

Posterior Polar Annular Choroidal Dystrophy: Genetic Insights and Differential Diagnosis in Inherited Retinal Diseases

Posterior polar annular choroidal dystrophy (PPACD) is a rare ocular disorder and presents as symmetric degeneration of the retinal pigment epithelium (RPE) and the underlying choriocapillaris, encircling the retinal vascular arcades and optic disc. This condition distinctively preserves the foveal region, optic disc, and the outermost regions of the retina. Despite its distinct clinical presentation, due to the infrequency of its occurrence and the limited number of reported cases, the pathophysiology, and the genetic foundations of PPACD are still largely uncharted. This review aims to bridge this knowledge gap by investigating potential genetic contributors to PPACD, assessing current findings, and identifying genes that warrant further study. Emphasis is also placed on the crucial role of multimodal imaging in diagnosing PPACD, highlighting its importance in understanding disease pathophysiology. By analyzing existing case reports and drawing comparisons with similar retinal disorders, this paper endeavors to delineate the possible genetic correlations in PPACD, providing a foundation for future genetic research and the development of targeted diagnostic strategies.