Dominant Cone Rod Dystrophy, Previously Assigned to a Missense Variant in RIMS1, Is Fully Explained by Co-Inheritance of a Dominant Allele of PROM1

Enhanced Learning and Memory in Patients with CRB1 Retinopathy

Mutations in the CRB1 gene are associated with a diverse spectrum of retinopathies with phenotypic variability causing severe visual impairment. The CRB1 gene has a role in retinal development and is expressed in the cerebral cortex and hippocampus, but its role in cognition has not been described before. This study compares cognitive function in CRB1 retinopathy individuals with subjects with other retinopathies and the normal population.

METHODS

Neuropsychological tests of cognitive function were used to test individuals with CRB1 and non-CRB1 retinopathies and compare results with a standardised normative dataset.

RESULTS

CRB1 retinopathy subjects significantly outperformed those with non-CRB1 retinopathy in list learning tasks of immediate (p = 0.001) and delayed memory (p = 0.007), tests of semantic verbal fluency (p = 0.017), verbal IQ digit span subtest (p = 0.037), and estimation test of higher execution function (p = 0.020) but not in the remaining tests of cognitive function (p > 0.05). CRB1 retinopathy subjects scored significantly higher than the normal population in all areas of memory testing (p < 0.05) and overall verbal IQ tests (p = 0.0012). Non-CRB1 retinopathy subjects scored significantly higher than the normal population in story recall, verbal fluency, and overall verbal IQ tests (p = 0.0016).

CONCLUSIONS

Subjects with CRB1 retinopathy may have enhanced cognitive function in areas of memory and learning. Further work is required to understand the role of CRB1 in cognition.

Phenotyping and genotyping inherited retinal diseases: Molecular genetics, clinical and imaging features, and therapeutics of macular dystrophies, cone and cone-rod dystrophies, rod-cone dystrophies, Leber congenital amaurosis, and cone dysfunction syndromes

Inherited retinal diseases (IRD) are a leading cause of blindness in the working age population and in children. The scope of this review is to familiarise clinicians and scientists with the current landscape of molecular genetics, clinical phenotype, retinal imaging and therapeutic prospects/completed trials in IRD. Herein we present in a comprehensive and concise manner: (i) macular dystrophies (Stargardt disease (ABCA4), X-linked retinoschisis (RS1), Best disease (BEST1), PRPH2-associated pattern dystrophy, Sorsby fundus dystrophy (TIMP3), and autosomal dominant drusen (EFEMP1)), (ii) cone and cone-rod dystrophies (GUCA1A, PRPH2, ABCA4, KCNV2 and RPGR), (iii) predominant rod or rod-cone dystrophies (retinitis pigmentosa, enhanced S-Cone syndrome (NR2E3), Bietti crystalline corneoretinal dystrophy (CYP4V2)), (iv) Leber congenital amaurosis/early-onset severe retinal dystrophy (GUCY2D, CEP290, CRB1, RDH12, RPE65, TULP1, AIPL1 and NMNAT1), (v) cone dysfunction syndromes (achromatopsia (CNGA3, CNGB3, PDE6C, PDE6H, GNAT2, ATF6), X-linked cone dysfunction with myopia and dichromacy (Bornholm Eye disease; OPN1LW/OPN1MW array), oligocone trichromacy, and blue-cone monochromatism (OPN1LW/OPN1MW array)). Whilst we use the aforementioned classical phenotypic groupings, a key feature of IRD is that it is characterised by tremendous heterogeneity and variable expressivity, with several of the above genes associated with a range of phenotypes.

Progressive Keratoconus in a Patient With Severe Pectus Excavatum and a Cartilage Oligomeric Matrix Protein Gene Mutation: A Case Report

INTRODUCTION

Keratoconus is a progressive ocular disorder associated with numerous systemic diseases, many of which affect the musculoskeletal system. Although the etiology and pathophysiology of the disorder remain elusive, recent studies suggest a significant role of genetic predisposition in the pathogenesis of keratoconus. This case report aims to elucidate a potential genetic association in a patient presenting with keratoconus, severe pectus excavatum, generalized muscular weakness, and skeletal deformities.

CASE DESCRIPTION

A 31-year-old Iranian man presented with progressively diminishing vision in both eyes over the years, eventually diagnosed with keratoconus. The patient's history and further examination indicated generalized muscular weakness, skeletal deformities, and severe pectus excavatum with cardiac and large vessel displacement. Whole-exome sequencing identified two heterozygous gene variants: one in the Cartilage Oligomeric Matrix Protein (COMP) gene and another in the Regulating Synaptic Membrane Exocytosis 1 gene. The patient's systemic and ocular symptoms, combined with the gene variants identified, suggested a connective tissue systemic disorder, potentially within the clinical spectrum of COMPopathies.

CONCLUSION

This is the first documented case of bilateral progressive keratoconus associated with severe pectus excavatum, generalized musculoskeletal dystrophy, and a COMP gene mutation. It highlights the necessity of continued search into the pathogenic genes of keratoconus, particularly in cases with coexisting systemic manifestations, to further our understanding of the etiology and pathogenesis of this complex disease.