Genotypes and phenotypes of hereditary eye diseases associated with early-onset high myopia / 中华实验眼科杂志

Objective:To analyze the genotype of hereditary eye diseases with early-onset high myopia (eoHM) and its relationship with phenotype.Methods:The families with eoHM were collected in Ningxia Eye Hospital from January 2019 to June 2020.The medical records of the probands and their family members were inquired and recorded in detail, and the relevant ocular examinations were performed.Peripheral venous blood samples were collected from patients and their family members, and whole-genome DNA was extracted.Sequence capture sequencing technology was applied to screen for disease-causing gene mutations in probands.The detected suspected pathogenic variants were verified by Sanger sequencing and were analyzed by family cosegregation analysis.According to ACMG guidelines, the pathogenicity of novel variants was evaluated.The original literature about hereditary eye diseases with eoHM was searched to analyze the relationship between mutated genes and clinical phenotype.This study protocol adhered to the Declaration of Helsinki.All subjects or their guardians were informed of the purpose and procedure of the study and signed the informed consent form.The study protocol was approved by the Ethics Committee of the People's Hospital of Ningxia Hui Autonomous Region (No.2016018).Results:A total of 20 eoHM families were collected, among which pathogenic variants associated with inherited eye diseases were detected in 8 families.Of the 8 probands, two were diagnosed with familial exudative vitreoretinopathy, one with X-linked retinitis pigmentosa, one with congenital stationary nightblindness, one with Stickler syndrome, one with achromatopsia, one with Leber congenital amaurosis, and one with gyrate atrophy of the choroid and retina.The first diagnosis age of the 8 probands was 4-7 years old, and they were all diagnosed as high myopia, with a refractive status ≤-6.00 DS.Genetic tests showed that the 8 probands carried a heterozygous variant c. 313A>G (p.M105Val) in FZD4 gene, a heterozygous variant c. 14_15insAAGA (p.Asp5fs *) in TSPAN12 gene, a heterozygous frameshift variant c. 2234_2237del (p.Arg745fs) in RPGR gene, a compound heterozygous variant of c. 481C>T (p.Gln161Ter *) and c. 355>T (p.Arg119Cys *) in GPR179 gene, a frameshift variant c. 1659_1660insACGGTGACCCTGGCCGTCCTGG (p.Pro554fs *) in COL2A1 gene, a compound heterozygous variant of c. 1811C>T (p.Thr604Ile *) and c. 967G>A (p.Gly323Ser) in PDE6B gene, a compound heterozygous variant of c. 604_619delTCCACGGCACTCAGGG (p.Ser202fs *) and c. 995G>C (p.Arg332Pro) in GUCY2D gene, a homozygous variant c. 772C>T (p.Pro241Leu) in OAT gene.Seven of them were novel variants.Compared with the previous literature, the clinical and gene phenotypes of the 8 families were analyzed in detail in this study, which provided the basis for the diagnosis of hereditary eye diseases with eoHM. Conclusions:EoHM is closely related to some hereditary eye diseases, which may be the reason for the early diagnosis of children and an important clue for clinicians to detect potential hereditary eye diseases.Further clinical evaluations of ocular structure and function as well as genetic screening in children with eoHM are recommended.

Cross-sectional observational analysis of the genetic referral practices across pediatric ophthalmology outpatient departments in an urban setting

Purpose: To analyze the genetic referral practices of pediatric ophthalmologists in an urban setting. Methods: (1) The first limb of the study: cross?sectional, observational study among children visiting the outpatient department of pediatric ophthalmology across five centers in Mumbai. All pediatric patients were screened separately by pediatric ophthalmologists and a clinical geneticist for their ophthalmic and systemic complaints. Children were marked for referral to genetics (RTG) by both the specialists based on identification of distinctive features (red flag) and were requested to meet a local geneticist. (2a) Twenty?three months later, patients who had been marked for RTG were contacted telephonically to follow?up if they had met the geneticist. (2b) Additionally, the last 20 proformas from each center were checked retrospectively to note the RTG marked by the ophthalmologist alone. Results: (1) In the first aspect of the study, 126 patients (male: female = 1.2:1) were included. Forty?nine (38.3%) patients were referred for genetic evaluation, of which three (6.1%), 31 (63.26%), and 15 (30.6%) cases were referred by the ophthalmologist alone, geneticist alone, and by both the specialists, respectively. Glaucoma (100%), nystagmus (86%), and leukocoria (83%) were the most prominent ocular diagnoses in cases referred for genetic evaluation. Facial dysmorphism (55.1%) and neurodevelopmental delays (51%) were among the most common systemic red flags found in patients referred to genetics. (2a) Twenty?three months later, on contacting the 49 patients marked for RTG, only one family had met the geneticist. (2b) Retrospective evaluation of 100 proformas: only three patients were marked for RTG by ophthalmologist alone. Conclusion: This study found that the genetic referrals by pediatric ophthalmologist were far lesser than those by geneticist. The study highlights an area of knowledge gap among pediatric ophthalmologists, prompting a need for heightened awareness in this area.

Applications of CRISPR/Cas9 genome editing technology in gene therapy for hereditary eye diseases / 中华实验眼科杂志

Clustered regulatory interspaced short palindromic repeat (CRISPR)/CRISPR associated nuclease (Cas) system is an adaptive immune system that confers resistance to exogenous virus or plasmid in bacteria and archaea,over the 30 years since its discovery,researchers have a better understanding of its immune processes in vivo and the mechanisms of gene editing by using its function. Researches found that CRISPR/Cas9 system modified from typeⅡCRISPR/Cas may edit genome accurately and effectively. In recent years,with the progress and development of gene sequencing technology,it is more explicit to make genetic diagnosis of a variety of hereditary eye diseases,and with the improvement of specificity for Cas9 in eukaryotic cells,gene editing is showing a great potential in the field of treating hereditary eye diseases. At present,the application of CRISPR/Cas9 gene editing technology has extended to the gene therapy of some hereditary eye diseases, such as congenital cataract, congenital glaucoma, retinitis pigmentosa (RP),congenital corneal dystrophy,Leber congenital amaurosis (LCA) and Usher syndrome. Besides,the combination of CRISPR/Cas9 gene editing technology with adeno-associated virus vectors (AAV) and induced pluripotent stem cells (iPSCs) research offers more possibilities and new approaches for the treatment of hereditary diseases. This article reviewed the mechanism of CRISPR/Cas9 and its applications in gene therapy for hereditary eye diseases.