Dystrophia canthorum in Waardenburg syndrome with a novel MITF mutation

AIM:To reveal a novel MITF gene mutation in Waardenburg syndrome(WS),which is an autosomal dominant inherited neurogenic disorder that consists of various degrees of sensorineural deafness and pigmentary abnormalities in the eyes,hair and skin.METHODS:The genetic analysis of the Chinese family was conducted by whole-exome sequencing,then the results were confirmed by Sanger sequencing.RESULTS:WS is classified into type I to IV,which are identified by the W index,clinical characteristics and additional features.The MITF gene mostly accounts for WS type II.In this study,a de novo heterozygous mutation in the MITF gene,c.638 A>G in exon 7,was identified in the patient diagnosed with WS type I features,as the W index was 2.17(over 2.10),with dystrophia canthorum,congenital bilateral profound hearing loss,bilateral heterochromia irides,premature greying of the hair,and excessive freckling on the face at birth.She also underwent refractive errors and esotropia,reduced pigmentation of the choroid and visible choroid vessels.The mutation was not found in previous studies or mutation databases.CONCLUSION:The novel mutation in the MITF gene,which altered the protein in amino acids 213 from the glutamic acid to glycine,is the genetic pathological cause for WS features in the patient.Those characteristics of this family revealed a novel genetic heterogeneity of MITF in WS,which expanded the database of MITF mutations and offered a possible in correcting the W index value of WS in distinct ethnicities.Moreover,ocular symptoms should be emphasized in all types of WS patients.

The impact of GJA3 SNPs on susceptibility to age-related cataract

AIM: To determine the association of gap junction protein alpha 3(GJA3) gene tag single-nucleotide polymorphisms(SNPs) with susceptibility to age-related cataract(ARC).METHODS: In total, 486 ARC patients were matched with 500 healthy controls. All the participants underwent complete ophthalmic examinations. Haplotype-tagging SNPs of GJA3 gene were selected from the HapMap Beijing Han Chinese population. Genomic DNA was extracted from the peripheral blood leukocytes of all the subjects.Under three different genetic models: dominant, recessive,and additive, the association between SNPs and ARC was examined. After adjusting for age and sex, the genetic effects of the GJA3 SNPs were evaluated with logistic regression analysis.RESULTS: Four tag GJA3 SNPs(rs6490519, rs9506430,rs9509053, and rs9552089) were included in the present study. None of the SNPs showed a significant relationship with an altered risk of total ARC under the dominant,recessive, or additive models. In the subgroup analysis,rs9506430 had a significant effect on the formation of a posterior subcapsular cataract(P=0.002, OR: 0.227, 95%CI:0.088-0.590) under the recessive model.CONCLUSION: Our study indicates that GJA3 variants may influence the development of posterior subcapsular cataracts. Further studies need to be designed to confirm this possibility.

Association of IGF1R polymorphisms(rs1546713) with susceptibility to age-related cataract in a Han Chinese population

AIM:To explore the susceptible association between the insulin-like growth factor-1 receptor(IGF1 R)single nucleotide polymorphism(SNP)and age-related cataract(ARC),and investigate the underlying mechanisms in human lens epithelium(HLE)cells.METHODS:Totally 1190 unrelated participants,comprising 690 ARC patients and 500 healthy individuals in Han Chinese population were recruited and genotyped for target SNP.Theχ2-test was used to detect genotypic distribution between the patient and control groups and the logistic regression was performed to adjust the age and gender.Meanwhile,different biological experimental methods,such as cell counting kit 8(CCK-8)assay,flow cytometry,quantitative real time polymerase chain reaction(Q-PCR)and Western blot,were used to detect cell viability,cell cycle progression and apoptosis in HLE cells or IGF1 R knockdown HLE cells.RESULTS:The rs1546713 in IGF1 R gene was identified(P=0.046,OR:1.606,95%CI:1.245-2.071),which shown a significant relevance with ARC risk under the dominant model.The results demonstrated that IGF1 R knockdown inhibited cell proliferation by inducing cell cycle arrested at S phase and promoting apoptosis.Mechanistically,the cell cycle blocked at S phase was linked with the alterations of cyclin A,cyclin B,cyclin E and P21.The pro-apoptosis function of IGF1 R may related with stimulating the activation of Caspase-3 and altering the expression levels of apoptotic proteins,including Bcl-2,Bax and Caspase-3.CONCLUSION:This study first report that IGF1 R polymorphisms may affect susceptibility to ARCs in Han Chinese population and provide new clues to understand the pathogenic mechanism of ARCs.Notably,IGF1 R is likely a potential target for ARC prevention and treatment.

Hydrogen peroxide-induced apoptosis of human lens epithelial cells is inhibited by parthenolide

AIM： To explore the effect of parthenolide on hydrogen peroxide（H_2O_2）-induced apoptosis in human lens epithelial（HLE） cells. METHODS： The morphology and number of apoptotic HLE cells were assessed using light microscopy and flow cytometry. Cell viability was tested by MTS assay. In addition, the expression of related proteins was measured by Western blot assay. RESULTS： Apoptosis of HLE cells was induced by 200 μmol/L H_2O_2, and the viability of these cells was similar to the half maximal inhibitory concentration（IC50）, as examined by MTS assay. In addition, cells were treated with either different concentrations（6.25, 12.5, 25 and 50 mol/L） of parthenolide along with 200 μmol/L H_2O_2 or only 50 μmol/L parthenolide or 200 mol/L H_2O_2 for 24 h. Following treatment with higher concentrations of parthenolide（50 μmol/L）, fewer HLE cells underwent H_2O_2-induced apoptosis, and cell viability was increased. Further, Western blot assay showed that the parthenolide treatment reduced the expression of caspase-3 and caspase-9, which are considered core apoptotic proteins, and decreased the levels of phosphorylated nuclear factor-κB（NF-κB）, ERK1/2 [a member of the mitogen-activated protein kinase（MAPK） family], and Akt proteins in HLE cells. CONCLUSION： Parthenolide may suppress H_2O_2-induced apoptosis in HLE cells by interfering with NF-κB, MAPKs, and Akt signaling.