CRB1 Gene Mutation Causing Different Phenotypes of Leber Congenital Amaurosis in Siblings

Voretigene Neparvovec and Gene Therapy for Leber's Congenital Amaurosis: Review of Evidence to Date

Gene therapy has now evolved as the upcoming modality for management of many disorders, both inheritable and non-inheritable. Knowledge of genetics pertaining to a disease has therefore become paramount for physicians across most specialities. Inheritable retinal dystrophies (IRDs) are notorious for progressive and relentless vision loss, frequently culminating in complete blindness in both eyes. Leber’s congenital amaurosis (LCA) is a typical example of an IRD that manifests very early in childhood. Research in gene therapy has led to the development and approval of voretigene neparvovec (VN) for use in patients of LCA with a deficient biallelic RPE65 gene. The procedure involves delivery of a recombinant virus vector that carries the RPE65 gene in the subretinal space. This comprehensive review reports the evidence thus far in support of gene therapy for LCA. We explore and compare the various gene targets including but not limited to RPE65, and discuss the choice of vector and method for ocular delivery. The review details the evolution of gene therapy with VN in a phased manner, concluding with the challenges that lie ahead for its translation for use in communities that differ much both genetically and economically.

CRB1-related retinopathy overlapping the ocular phenotype of S-adenosylhomocysteine hydrolase deficiency

BACKGROUND

S-adenosylhomocysteine hydrolase deficiency due to pathologic variants in AHCY gene is a rare neurometabolic disease for which no eye phenotype has been documented. Pathologic variants in CRB1 gene are known to cause a wide spectrum of autosomal recessive retinal diseases with Leber's congenital amaurosis as a most common. The aim of this study is to report co-inheritance of neurometabolic disease and eye disease in a pedigree.

MATERIALS AND METHODS

Comprehensive eye examination was performed in available family members together with color vision test, visual fields, fundus images, OCT, electroretinogram and visual evoked potentials. Genetic testing included whole-exome sequencing (WES), retinal dystrophy gene panel and segregation analysis.

RESULTS

Two children from a family not known to be consanguineous were affected with neurometabolic disease and one of them presented with reduced vision due to maculopathy. The mother had symptoms of retinal degeneration of unspecified cause. Clinical WES revealed homozygous missense pathologic variants in AHCY gene c.148G>A, p.(Ala50Thr) as a cause of S-adenosylhomocysteine hydrolase deficiency. Retinal dystrophy gene panel sequencing revealed two heterozygous missense pathologic variants in CRB1 gene c.1831T>C, p.(Ser611Pro) and c.3955T>C, p.(Phe1319Leu) in the proband and her mother. These variants segregated with disease phenotype in family members.

CONCLUSIONS

Establishing an ocular genetic diagnosis may be challenging with the co-existence of a rare systemic genetic disease with previously unknown eye involvement. Extensive phenotyping and genotyping of available family members showed that the proband and her mother shared a CRB1-related retinopathy at different stages while the brother did not.

Identification of an Individualized Prognostic Signature Based on the RWSR Model in Early-Stage Bladder Carcinoma

Bladder cancer (BLCA) is the fourth common cancer among males in the United States, which is also the fourth leading cause of cancer-related death in old males. BLCA has a high recurrence rate, with over 50% of patients which has at least one recurrence within five years. Due to the complexity of the molecular mechanisms and heterogeneous cancer feature, BLCA clinicians find it hard to make an efficient management decision as they lack reliable assessment of mortality risk. Meanwhile, there is currently no screening suitable prognostic signature or method recommended for early detection, which is significantly important to early-stage detection and prognosis. In this study, a novel model, named the risk-weighted sparse regression (RWSR) model, is constructed to identify a robust signature for patients of early-stage BLCA. The 17-gene signature is generated and then validated as an independent prognostic factor in BLCA cohorts from GSE13507 and TCGA_BLCA datasets. Meanwhile, a risk score model is developed and validated among the 17-gene signature. The risk score is also considered an independent factor for prognosis prediction, which is confirmed through prognosis analysis. The Kaplan-Meier with the log-rank test is used to assess survival difference. Furthermore, the predictive capacity of the signature is proved through stratification analysis. Finally, an effective patient classification is completed by a combination of the 17-gene signature and stage information, which is for better survival prediction and treatment decisions. Besides, 11 genes in the signature, such as coiled-coil domain containing 73 (CCDC73) and protein kinase, DNA-activated, and catalytic subunit (PRKDC), are proved to be prognosis marker genes or strongly associated with prognosis and progress of other types of cancer in published literature already. As a result, this paper would more accurately predict a patient's prognosis and improve surveillance in the clinical setting, which may provide a quantitative and reliable decision-making basis for the treatment plan.