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.
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.
Epigenetics refers to the changes in gene expression level and function caused by non-genetic sequence changes. It can provide the time, location and mode of the genetic information for the execution of DNA sequences, including DNA methylation, histone modification, non-coding RNA and chromatin remodeling. Studies had shown that epigenetics plays an important role in the development of diabetic retinopathy (DR), and it had been found that epigenetic-related treatment regimens had a certain effect on the treatment of DR through animal experiments and in vitro experiments. It was benefit to regulate the development of diabetes and its complications by depth study of DNA methylation, histone modification, miRNA and metabolic memory. An understanding of changes in gene transcriptional mechanisms at the epigenetic level could help us to further study the prevention and control of diabetes and its complications, and to provide new ideas for treatment.
Mycobacterium tuberculosis is the causative agent of human tuberculosis. Through the genotyping of Mycobacterium tuberculosis, we can find the epidemic situation and characteristics of tuberculosis in time, analyze the transmission chain between patients in different jurisdictions, and formulate effective intervention measures in time, to provide a strong basis for clinical diagnosis and treatment. At present, several genotyping techniques for Mycobacterium tuberculosis have their advantages and disadvantages in application. This article reviews the genotyping technology, population genetics and genotyping naming rules of Mycobacterium tuberculosis.
X-linked retinoschisis (XLRS) is a rare X-linked inherited retinal disorder, caused by mutations in retinoschisin 1 (RS1) gene. Three XLRS mice were established, providing ideal systems to study the mechanism and treatment methods for XLRS. RS1 gene mutations can induce abnormal secretion or adhesion function of RS1 protein. In the past year, phase I clinical trials for XLRS has begun in USA, using adeno associated virus (AAV, AAV8 or AAV2)-mediated gene delivery. With the rapid development of new generation of AAV vector that can transduce more retinal cells through intravitreous delivery, gene therapy for XLRS will have a brighter future.
OBJECTIVE:The hereditary form of retinoblastoma(RB)is a monogenic disorder which is due to germinal mutation of RB susceptibility gene located on 13q14.The majority of hereditary RB cases transmit as a Mendelian autosomal dominant inheritance that 50% of the offspring of a carrier will inherit the disorder susceptibility gene and all carriers will develop the disorder.The authors report 3 hereditary RB families with incompleted penetrance and irregular transmission of RB phenotype. METHOD:RFLPsamp;VNTRs for analysis of haplotype and SSCPamp;direct DNA sequencing for determination of RB point mutation. RESULTS:The mosaicism of Rb gene point mutation resulted in the incompleted penetrance and irregular transmission of RB phentype. CONCLUSION:DAN-based diagnosis can be used to differentiate the hereditary and nonhereditary forms of retinblastoma but only is the direct detection of disease-causing mutation reliable for determnation of carrier and estimation of th e risk for retinoblastoma. （Chin J Ocul Fundus Dis,1996,12: 37- 40）
Objective To analyze the BEST1 gene mutations and clinical features in patients with multifocal vitelliform retinopathy (MVR). Methods This is a retrospective case series study. Five MVR families with MVR, including 9 patients and 10 healthy family members were recruited. Clinical evaluations were performed in all MVR patients and their family members, including best-corrected visual acuity (BCVA), intraocular pressure (IOP), refraction, slit-lamp examination, 90 D preset lens examination, gonioscopy, color fundus photography, optical coherence tomography (OCT), fundus autofluorescence (AF), ultrasound biomicroscopy (UBM) and axial length measurement. Electro-oculogram (EOG) was performed in 12 eyes and visual field were performed in 13 eyes. Peripheral blood samples were collected in all subjects to extract genomic DNA. Coding exons and flanking intronic regions of BEST1 were amplified by polymerase chain reaction and analyzed by Sanger sequencing. Results Among the 5 MVR families, 3 probands from three families had family history, including 1 family had autosomal dominant inheritance pattern. Two patients from 2 families were sporadic cases. Screening of BEST1 gene identified four mutations, including three missense mutations (c.140G>T, p.R47L; c.232A>T, p.I78F; c.698C>T, p.P233L) and 1 deletion mutation (c.910_912del, p.D304del). Two mutations (p.R47L and p.I78F) were novel. The BCVA of affected eyes ranged from hand motion to 1.0. The mean IOP was (30.39±11.86) mmHg (1 mmHg=0.133 kPa). The mean refractive diopter was (-0.33±1.68) D. Twelve eyes had angle-closure glaucoma (ACG) and 4 eyes had angle closure (AC). EOG Arden ratio was below 1.55 in all patients. The mean anterior chamber depth was (2.17±0.29) mm. Visual field showed defects varied from paracentral scotoma to diffuse defects. The mean axial length was (21.87±0.63) mm. All MVR patients had multifocal vitelliform lesions in the posterior poles of retina. ACG eyes demonstrated pale optic disc with increased cup-to-disc ratio. OCT showed retinal edema, extensive serous retinal detachment and subretinal hyper-reflective deposits which had high autofluorescence in AF. The genetic testing and clinical examination were normal in 10 family members. Conclusions MVR patients harbored heterozygous mutation in the BEST1 gene. Two novel mutations (p.R47L and p.I78F) were identified. These patients had clinical features of multifocal vitelliform retinopathy and abnormal EOG. Most patients suffered from AC/ACG.
Objective To analyze the new primary mutation in Chinese people with Leberprime;s hereditary optic neuropathy (LHON). Methods Genomic DNA was collected from 260 suspected LHON patients and 100 normal healthy persons. The mitochondria DNA mutation at nucleotide position (NP) 15257 and the hot spot (14452-14601 bp) of ND6 gene which include the mutations at NP (14482, 14498, 14568, 14596, 14495, and 14459) were screened by using polymerase chain reaction (PCR), heteroduplex-single strand conformation polymorphism (HA-SSCP) and restriction fragment length polymorphism (RFLP) analysis and sequencing. Primary mutation spectrum of Chinese race was analyzed. Results Eight kinds of polymorphism of mitochondria DNA were found in 260 suspected LHON patients and 100 normal healthy persons, including NP 14488C, 14518G, and 14617G which hadnrsquo;t been reported (http://www.mitomap.org/). No mutation at NP 15257, 14482, 14498, 14568, 14596, 14495, and 14459 was found. Conclusion The NP 15257A may not be the primary mutation in Chinese. Because of the race difference, 14452-14601 bp in ND6 gene may not be the hot spot in Chinese patients with LHON, and other hot spots may exist. (Chin J Ocul Fundus Dis, 2006, 22: 82-85)
RNA can be labeled by more than 170 chemical modifications after transcription, and these chemical modifications are collectively referred to as RNA modifications. It opened a new chapter of epigenetic research and became a major research hotspot in recent years. RNA modification regulates the expression of genes from the transcriptome level by regulating the fate of RNA, thus participating in many biological processes and disease occurrence and development. With the deepening of research, the diversity and complexity of RNA modification, as well as its physiological significance and potential as a therapeutic target, can not be ignored.
ObjectiveTo reveal the pathogenic mutation in a three-generation Chinese family with autosomal dominant familial exudative vitreoretinopathy (FEVR). MethodsThree patients and a healthy spouse from the index family with FEVR were recruited. The proband was a 5 years old boy. His mother and grandpa were presented with typical FEVR presentations, while his father with normal ocular fundus. DNA was extracted from peripheral blood samples taken from all four participants. All coding and exon-intron boundary regions of five targeted genes, including NDP, FZD4, LRP5, TSPAN12 and ZNF408 were amplified with polymerase chain reaction and sequenced using direct sequencing. In silico analyses were applied to determine the conservation of the mutation site, pathogenic effect and the potential protein crystal structural changes caused by the mutation. ResultsFZD4 c.478G > A, a susceptible mutation was found after four high frequency mutation sites which MAF values were higher than 0.001 was filtered among 5 single nucleotide variations detected in four participants, leading to the residue 160 changing from glutamate to lysine (p.E160K). Co-segregation analysis between genotypes and phenotypes revealed FZD4 p.E160K as the disease-causing mutation for this family. Conservational analysis suggested that this mutation site was highly conserved among all tested species. Functional analysis predicated that this mutation may be a damaging mutation. Crystal structural analysis also indicated that this mutation could lead to the elimination of the hydrogen bond between residue 160 and asparagine at residue 152, thus altering the tertiary structure of the protein and further impairing the protein function. ConclusionOur study demonstrates FZD4 p.E160K as a novel pathogenic mutation for FEVR.