Objective To review the research progress in relationship between hereditary diffuse gastric cancer (HDGC) and CDH1 gene. Methods Literatures on HDGC which were published in recent years were collected and analyzed. Results Aberrant CDH1 gene is significantly correlated with HDGC: mutations of CDH1 exons play the most important role in pathogenesis of HDGC. Screening CDH1 gene mutation is useful for diagnosis of HDGC as well as the treatments. Alterations of CDH1 other than exon mutation, such as intron mutation, gene promoter methylation and single nucleotide polymorphism may result in downregulation of the gene expression. Further study should be done to confirm the roles of these alterations. Conclusions Alterations of CDH1 gene are significantly associated with the pathogenesis of HDGC. Detecting alterations of CDH1 gene are important for diagnosis and management of HDGC as well as to get insights of the pathogenesis of the disease.
ObjectiveTo study the characteristics of the genotype and phenotypic in a family with X-linked retinoschisis (XLRS) due to RS1 mutation. MethodsA retrospective clinical study. An XLRS family of 4 generations of 26 people were included in the study. Among them, 8 participants were males and 7 participants were females. Routine ophthalmologic examination was performed on 3 patients in the family including the proband and 12 patients with normal phenotype. Optical coherence tomography was performed in 2 of the 3 patients. Peripheral venous blood was extracted from all participants, whole-genome DNA was extracted, and potential pathogenic genes were screened by Panel sequencing. Conservative analysis, pathogenicity analysis and protein structure prediction were carried out by software tools. The pathogenicity of gene mutations was analyzed according to the American Society of Medical Genetics and Genomics (ACMG) guidelines. ResultsThe proband was 3 years old. Optical coherence tomography (OCT) examination showed that the retinal core layer in the macular area of both eyes had a cystic change, which was segmented by vertical or oblique bridging tissue. The proband's uncle was 32 years old. OCT examination showed atrophy in the macular area of the left eye. The macular area of the right eye was cystoid, segmented by vertical or oblique bridging tissue. No abnormality was found in the fundus examination of the proband's parents and 10 members of his family. Panel sequencing showed that c.361C>T/ p.Q121X hemizygous mutation was found in the fifth exon of RS1 gene in the proband (Ⅳ3) and 2 patients (Ⅱ1, Ⅲ8). The mother was a heterozygous mutation carrier of the gene, while the father had no mutation. The mutant gene causes premature termination of RS1, a truncated protein encoding 224 amino acids to 120 amino acids. Of the 10 patients with normal fundus examination, 6 participants were normal. The mutation was carried by four people, which were women. Homology analysis of the protein sequence showed that the mutant site was highly conserved in 12 mammals. Three-dimensional structural analysis of RS1 protein showed that the c-terminal amino acid sequence of the mutant protein was more than 50% missing. Analysis of ACMG guidelines indicated that the mutation was pathogenic. ConclusionThe RS1 mutation site c.361C>T/p.Q121X is a new mutation site of XLRS.
Objective To screen and analyze NR2E3 gene mutations in rentinitis pigmentosa (RP) patients from Ningxia area of China. Method 120 RP patients were enrolled in this study. The patients include 33 autosomal dominant RP (ADRP) patients from 18 families, 20 autosomal recessive RP (ARRP) patients from 15 families, and 67 simplex RP (SRP) patients.100 healthy people were collected as the control group. PCR and direct DNA sequencing were used to screen the entire coding region and splice sites of NR2E3 gene. Multiple analysis was used to study the effects of NR2E3 gene on RP. ResultsA total of 12 different sequence variants in the NR2E3 gene were identified, including 6 novel sequence variants. 5 variants were detected in non-coding regions; 7 variants were detected on the 4th, 6th, 7th exon which including 3 synonymous mutations and 4 missense mutations. All of them were NR2E3 gene polymorphisms and showed no positive correlation with the RP confirmed by the multivariate logistic regression analysis. The missense mutation of p.Glu121Lys was first found in 1 ADRP proband, 2 SRP patients and 2 control subjects. Among other 8 affected individuals in this ADRP family, 5 patients also had the p.Glu121Lys variant. Notably, the 6 affected individuals with p.Glu121Lys showed more serious ophthalmic findings (early onset and early central visual impairment) than other 3 affected individuals without p.Glu121Lys.Conclusion The mutation frequency of NR2E3 and p.Glu121Lys variant in NR2E3 gene in Ningxia RP patients were lower than previous reports in other populations.
ObjectiveTo observe and analyze the pathogenic gene types and clinical phenotypes of Leber congenital amaurosis (LCA).MethodsA retrospective clinical study. Six patients with LCA confirmed by genetic testing and 18 family members were included in the study. The patients came from six unrelated families. The family was investigated with a specific hereditary eye disease enrichment panel which contained 463 known pathogenic genes and based on targeted exome capture technology first to indentify the potential pathogenic genes and mutations. Then the TULP1, RPGRIP1, GUCY2D pathogenic mutations were conformed by Sanger sequencing. The pathogenicity of the gene variation was searched through relevant databases and PubMed literature, and its function was explained by protein prediction software.ResultsOf the 6 patients, 3 were males and 3 were females; the age was from 3 to 33 years. Nystagmus, finger pressing eyes, photophobia, and night blindness were seen in 5 cases; electroretinogram showed 3 cases of extinction or near extinction; and 4 cases of retinopathy. The results showed patients with compound heterozygous mutation of c.1318C＞T and c.1142T＞G, homozygous mutation ofc.1318C＞T and compound heterozygous mutation of c.1153G＞A and c.1561C＞T of TULP1 in Family 1, Family 2 and Family 5, respectively. There were compound heterozygous mutations of RPGRIP1 c.391delG and c.1468-2A＞G in Family 3 and c.715delA and c.1765C＞T in Family 6, respectively. Homozygous mutation of c.3177_3178delAC of GUCY2D was found in Family 4.The parents of all six patients were carriers of corresponding heterozygous mutations.TULP1 gene c.1142T＞G, RPGRIP1 gene c.391delG, c.715delA and c.1765C＞T and GUCY2D gene c.3177_3178delAC mutations were novel mutations and unreported. The 381th amino acid locus of product protein of TULP1 gene was highly conserved among species. The protein prediction software predicted that the mutation pathogenic. The c.391delG, c.715delA and c.1765C＞T mutations of RPGRIP1 gene and c.3177_3178delAC mutation of GUCY2D gene can lead to early translation termination of their product proteins, which are pathogenic variants.ConclusionThe pathogenic mutations of TULP1, RPGRIP1 and GUCY2D genes led to LCA 15, LCA 6 and LCA 1 in six families.
ObjectiveTo identify SCN9A gene mutation in a family with severe primary erythermalgia. MethodsClinical data of family were collected and the encoding exons and their flanking sequences of SCN9A gene were amplified and sequenced from genomic DNA samples. ResultsA heterozygous c.1185C→G was found in exon 9 of the proband, which resulted in N395K amino acid substitution. The mutation was not detected in the proband’s healthy mother or 50 unrelated healthy controls. ConclusionThe missense mutation of SCN9A gene is the underlying cause of the patient’s clinical phenotype.
ObjectiveTo explore the genotype and phenotype of PCDH19 gene related epilepsy.Methods41 probands, including 39 girls and 2 boys collected from pediatric department of the Peking University and Neurology Department of Wuhan Children's Hospital from February 2005 to April 2017, were diagnosed as PCDH19 gene related epilepsy. The clinical features of the probands and affected relatives were retrospectively analyzed. PCDH19 mutations were detected by Sanger sequencing or targeted next generation sequencing (NGS) and multiple ligation-dependent probe amplification (MLPA).Results40 in 41 probands with PCDH19 mutations were detected by sequencing and one was detected by MLPA.Two male epilepsy patients with mosaic PCDH19 mutations were detected by NGS with the mutant allele fraction of 85% and 33%. Among 39 female probands, 19 were with inherited mutations and 20 were de novo mutations. The penetrance of females with PCDH19 mutation was estimated as 90% (53/59). Twelve hemizygous fathers and one mosaic father were asymptomatic.The clinical phenotypes of female mutation carriers included epilepsy with mental retardation, Dravet syndrome, febrile seizures, or even asymptomatic. The phenotypic heterogeneity was noticed in females with identical mutations even in members from the same family. The median seizure onset age of 46 patients (including 41 probands and 5 affected relatives) were 11 months (range 4~42months).During the course, 87% (40/46) patients experienced generalized tonic clonic seizures (GTCSs) and 69.6% (32/46) experienced focal seizures. Other rare seizures types included myoclonic seizures (6/46), absence seizures (3/46) and atonic seizures (1/46). Seizures in clusters were observed in all patients, fever sensitivity in 80.4% (37/46), and status epilepticusin only three, cognitive impairment in 76% (35/46) and 7 with autistic features.ConclusionMutations in PCDH19 can be inherited or de novo. Most patients are females, rare mosaic males can be affected or asymptomatic. PCDH19 gene related epilepsy shows incomplete penetrance and variable expressivity.Seizures occurring in clusters and sensitive to fever are the major features.
Objective To compare the differences of chromosome aberration and Rb 1 gene mutation among 3 cloned cells of SO-Rb50 cell line of retinoblastoma. Methods 1.Three cell cloned strains named MC2, MC3, MC4 were isolated from SO-Rb50. 2. Gbanding and karyotype analysis were performed on the llth passage cells of the 3 cell strains.3.All exons and the promoter region of the Rb gene were detected by PCR-SSCP analysis in tumor cell DNA extracted from the 3 cell strains. Results 1.Both numerical and structural chromosomal aberrations could be observed in these 3 cell strains.Several kinds of structural chromosomal aberrations were observed.The chromosome aberrations in the same passage of different cell strains were different.Aberration of chromosome 13 was rare and the aberration feature was different in the 3 cell strains.Five marker chromosomes were identified.M1,t(1;1)qter-p35∷q24-ter could befound in all cell strains.Two of them M4 and M5,have not been reported in SO-Rb50 cell line previously.2.SSCP analysis of exon 24 showed that MC411 and MC3138 had abnormal band. Conclusions The characteristics of heterogeneity of the original tumor cell line SO-Rb50are still kept during a long-term culture in vitro and the cloned strains had dynamic changes during this period.Aberration of chromosome 13 is not the only cause of RB;aberration of chromosome 1,a commom event in some neoplasias as well as in SO-Rb50, plays a meaningful role in the immortalization of this cell line. (Chin J Ocul Fundus Dis, 1999, 15: 146-148)
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 investigate the mutations of the gene in Chinese patients with X linked juvenile retinoschisis (XLRS), and to provide the genetic diagnosis and consultation of heredity for the patients and their families. Methods Genomic DNA was isolated from leukocytes of 29 male patients with XLRS, 38 female carriers and 100 normal controls (the patients and the carriers were from 12 families). All 6 exons of XLRS1 gene were amplified by polhism (SSCP) assay. The positions and types of XLRS1 gene mutations were determined by direct sequencing. Results Eleven different XLRS1 mutations were identified in these 12 families, including one frameshift mutation due to base loss of the first exon: c.22delT（L9CfsX20）, one nonsense mutation due to base loss of the first exon (Trp163X), one splice donor site mutation(c.52+2 Trarr;C; IVS1+2T to C), and eight missense mutation due to base replacement（Ser73Pro, Arg102Gln, Asp145His, Arg156Gly, Arg200Cys, Arg209His, Arg213Gln, and Cys223Arg). No gene mutation was detected in the control group. Four new mutations included frmaeshift mutation（L9CfsX20）and mutations of Asp145His, Arg156Gly, and Trp163X at the fifth exon. A newly discovered non-disease-related polymorphism (NSP) was the c.576C to T (Pro192Pro) change at the sixth exon. Conclusion Eleven different XLRS1 mutations were detected, which is the cause of XLRS in Chinese people. The detection of gene mutations may provide the guidance of genetic diagnosis and the consultation of family heredity for the patients and their families. (Chin J Ocul Fundus Dis, 2006, 22: 77-81)
Objective To investigate the feasibility of detection of epidermal growth factor receptor ( EGFR) exon 19 deletions and exon 21 L858R mutations in pleural effusion fromnon-small-cell lung cancer ( NSCLC) patients by mutant enriched PCR assay. Methods The mutations of exon 19 and 21 of EGFR gene in pleural samples fromthirty NSCLC patients were analyzed using both the mutant-enriched PCR assay and the non-enriched PCR assay. Results Ten ( 33. 3% , 10/ 30) exon 19 deletions and five ( 16. 7% , 5/30) exon 21 L858R mutation were detected by the mutant-enriched PCR assay, while only 6 cases ( 20. 0% ) and 1 case ( 3. 3% ) were detected by the non-enriched PCR assay respectively. The difference of mutation detection rate of EGFR gene between the two methods was statistically significant ( P = 0. 032) . Mutations were detected in all of partial responders ( 2 /4) among the four patients who received gefitinib therapy. Conclusions Mutant-enriched PCR assay can detect EGFR exon 19 deletions and exon 21 L858R mutation in pleural effusion from NSCLC patients effectively, economically and accurately. It may be a valuable biomarker for gefitinib therapy in advanced NSCLC.