Epigenetic modifications such as DNA methylation, histone post-translational modifications, non-coding RNA are reversible, heritable alterations which are induced by environmental stimuli. Major risk factors of diabetes and diabetic complications including hyperglycemia, oxidative stress and advanced glycation end products, can lead to abnormal epigenetic modifications in retinal vascular endothelial cells and retinal pigment epithelium cells. Epigenetic mechanisms are involved in the pathogenesis of macular edema and neovascularization of diabetic retinopathy (DR), as well as diabetic metabolic memory. The heritable nature of epigenetic marks also playsakey role in familial diabetes mellitus. Further elucidation of epigenetic mechanisms in DR can open the way for the discovery of novel therapeutic targets to prevent DR progression.
Inherited retinal degenerations (IRD) are a group of diseases with high genetic heterogeneity and differences in inheritance patterns, age of onset and severity of visual dysfunction. It is one of the leading causes of blindness. In recent years, gene therapy becomes a popular research area in the treatment of genetic diseases due to the rapid development of gene diagnosis technology. Several clinical trials worldwide have proved the safety and effectiveness of gene therapies in IRD. Clinical application of adeno-associated virus -mediated gene therapies for Leber congenital amaurosis and choroideremia clinical trials indicate that patients' retinal functions were improved at different levels after treatment. There are a number of other IRD clinical trials ongoing currently, which bring new possibilities to treat IRD. This article reviews the pathogenesis of IRD, gene vectors and clinical trials in IRD.
Objective To investigate the relationship between diabetic retinopathy (DR) and insertion/deletion (a/b) polymorphism of a 27 base pair variable number tandem repeat (VNTR) in intron 4 of the endothelial nitric oxide synthase (eNOS) gene. Methods 321 patients of type 2 diabetes mellitus with over 10 years duration (case group) and 146 normal subjects (control group) were enrolled in this study. All the clients are Han Chinese. The case group was divided into DR subgroup (154 patients) and non-DR (NDR) subgroup (167 patients) according to the results of indirect ophthalmoscope and fundus fluorescent angiography. The VNTR polymorphism in eNOS gene was determined by polymerase chain reaction (PCR) combined with 8% agarose gel electrophoresis. Then the b, a allele frequency and b/b, a/a, b/a allele frequency of two groups were compared, and its correlation with diseases were analyzed. Results The b allele frequency of the VNTR in intron 4 of eNOS gene in the DR group was significantly higher than that in the NDR group（chi;2=4.745，P=0.029；OR=1.685，95%CI=1.050-3.905）and control group（chi;2=6.958，P=0.008；OR=1.891，95%CI=1.172-4.437）; b/b allele frequency in the DR group was also significantly higher than that in the NDR group（chi;2=4.811，P=0.028；OR=1.790，95%CI=1.060-4.645）and control group（chi;2= 5.203，P=0.023；OR=1.859，95%CI=1.087-4.952）. Conclusions The b allele and b/b genotype in intron 4 of eNOS gene in the Han Chinese are closely related to DR.
ObjectiveTo investigate the association of high density lipoprotein cholesterol (HDL-C) and cholesterol ester transfer protein (CETP) TaqIB mutation with non-arteritic anterior ischemic optic neuropathy (NA-AION) in the Shaanxi Han ethnic population.
MethodsThe study cohort consisted of 45 individuals that had been diagnosed with NA-AION and 45 healthy controls (matched for age, gender). None of the cases or controls had a history of diabetes, serious cardio-cerebral vascular diseases, liver and kidney dysfunction that might influence plasma lipid levels. Plasma HDL-C was detected by enzyme-linked immunosorbent one-step, through the Toshiba TBA-40FR automatic biochemical analyzer. CETP TaqIB gene polymorphism was determined by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) techniques for analysis. B2B2 genotype was only a fluorescence band with 535 bp; B1B1 genotype was 2 fluorescence bands with 361, 174 bp; B1B2 genotype was 3 fluorescence bands with 535, 361, 174 bp. The relative risk of genotype, HDL-C and disease occurrence was analyzed by logistics regression analysis.
ResultsThere have no significant difference between NA-AION patients and controls about plasma total cholesterol level and triglyceride level (t=1.907, 1.877; P > 0.05). The plasma HDL-C levels were significantly lower in NA-AION patients than in controls (t=2.367, P=0.022). Compared with controls, the prevalence of B1B1 genotype and B1 allele was higher (χ2=17.289, P=0.001), the prevalence of B2 allele (χ2=15.648, P=0.000) was lower in NA-AION patients. The lower concentration of HDL-C was risk factor of NA-AION (odds ratio=6.143, 95% confidence interval 1.262-29.895, χ2=27.676;P=0.013). The proportion of B1B1 genotype was significantly higher in NA-AION patients than in controls (odds ratio=2.24, 95% confidence interval 2.427-36.323, χ2=10.526; P=0.001).
ConclusionsThe low plasma HDL-C is independent risk factor for NA-AION and is associated with the development of NA-AION in the Shaanxi Han ethnic population. CETP TaqIB mutation is associated with low plasma HDL-C in NA-AION in the Shaanxi Han ethnic population.
ObjectiveTo investigate the difference of DNA methylation before and after bariatric surgery.MethodThe relevant literatures of the research on the changes of DNA methylation level and gene expression regulation in blood and tissues before and after bariatric surgery were retrieved and reviewed.ResultsDNA methylation was an important method of epigenetic regulation in organisms and its role in bariatric surgery had been paid more and more attention in recent years. Existing studies had found that there were changes of DNA methylation in blood and tissues before and after bariatric surgery. The degree of methylation varies with different follow-up time after bariatric surgery and the same gene had different degrees of methylation in different tissues, and some even had the opposite results.ConclusionsDNA methylation levels before and after bariatric surgery are different in different tissues. And studies with larger sample size and longer follow-up time are needed, to further reveal relationship among DNA methylation, obesity, and bariatric surgery.
ObjectiveTo observe the transthyretin (TTR) gene mutation, protein and mRNA expression in patients with familial vitreous amyloidosis.
MethodsSubjects were divided into three groups: (1) illness group: seven patients with familial vitreous amyloidosis. (2) No-illness group: 9 unaffected family members. (3) Control group: 9 healthy individuals in same area. Subjects' peripheral venous blood were collected and DNA were extracted, 4 exons of TTR gene were amplified by reverse transcription polymerase chain reaction(RT-PCR), the gene fragments were sequencing by the fluorescence labelling method. Serum TTR protein expression was detected by Western blot, and TTR mRNA in leukocyte was assayed by RT-PCR.
Results4 exons of TTR gene of all samples were amplified, and DNA sequencing data showed that 7 patients and 3 subjects DNA from unaffected family members had mutated in the 3rd exon of 107th base, changing from G to C. Heterozygous mutation occurred in codon of the 83th amino acid in exon 3, namely, Gly83Arg, resulted in the change of GGC to CGC. The protein and mRNA expression of TTR was lower in illness group than no-illness group and control groups(P < 0.05). Compared with control group, TTR mRNA expression in unaffected family members groups was significant decreased(P < 0.05).
ConclusionHeterozygous mutation occurred in codon of the 83th amino acid in exon 3, namely Gly83Arg, and suggested that Gly83Arg is connected with the change of TTR mRNA and protein expression.
The rapid development of genetic diagnosis-related technologies has paved a wide road for gene therapy. Different gene therapy clinical trials for retinal disorders, including gene-replacement therapy, anti-neovascular gene therapy and opotogenetic gene therapy, have been developed and achieved fruitful results, which have gradually confirmed the efficacy and safety of adeno-associated virus (AAV)-mediated gene therapy for recessive retinal diseases. In recent years, novel gene editing technologies also shows great potential to treat dominant retinal disease, or recessive retinal disease when the therapeutic gene fragments are too long to fit into the AAV vectors. These results make it possible for most of the patients with inherited retinal diseases to be treated by the safe and effective AAV-mediated gene therapy, which will also benefit Chinese patients soon.
ObjectiveTo analyze the pathogenic gene types and phenotypic characteristics of 6 albinism families. Methods A retrospective series of case studies. Six probands of albinism and 20 family members were recruited for this study, 5 probands with clinical manifestations of oculocutaneous albinism (OCA) and 1 proband of ocular albinism (OA). Genomic DNA was extracted from peripheral venous blood which was collected from 6 probands and 20 family members. Genetic variations were screened by whole-exome sequencing or Sanger sequencing and then analyzed the relationship between genotypes and phenotypes. Results Genetic sequencing identified 6 potential pathogenic variants in 4 probands, including 2 compound heterozygous mutations in the 2 genes [TYR (c.1037-7T＞A, c.925_c.926insC), OCA2 (c.2359G＞A, c.587T＞C)] associated with OCA1 and OCA2, and 2 hemizygous mutations in the GPR143[GPR143 (c.11C＞G), GPR143 (c.333G＞A)] associated with OA1, respectively. In which, 5 were novel mutations and confirmed by Sanger sequencing. One case was accorded with OCA in clinical phenotype, but genetic diagnosis was OA1, the others were agreement between clinical diagnosis and genetic diagnosis. Conclusion There are 4 families with mutations in 6 families, representative of 3 type of albinism (OCA1, OCA2, OA1).
Epigenetics refers to heritable changes in gene expression independent of DNA nucleotide sequence itself, and the main mechanisms include DNA methylation, histone modifications, noncoding RNAs, and so on. Vascular disease is a chronic disease regulated by the interaction between environmental and genetic factors. In recent years, more and more studies have confirmed that epigenetic regulation plays an important role in the occurrence and development of vascular diseases. This article reviews recent advances in epigenetics in vascular disease.
Pulmonary arterial hypertension (PAH) is a fatal and complex disease characterized by multifactorial involvement in pulmonary vascular remodeling, leading to heart failure. It is difficult to treat and has a poor long-term prognosis. Recent studies highlight the significant role of epigenetic modulation in the pathophysiological progression of PAH, offering new therapeutic approaches to improve clinical outcomes. This article summarizes the role of epigenetic modulation in the development and progression of PAH, focusing on deoxyribonucleic acid methylation, ribonucleic acid methylation, histone modifications, and non-coding ribonucleic acid, in order to understand the role of epigenetic modulation in PAH and identifying new evaluation indexes and therapeutic targets, thereby improving the prognosis of PAH.
