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The prenatal diagnosis of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) by mutation analysis.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an important cause of hereditary stroke. Mutations in the Notch3 gene are clearly causally linked to this progressive vascular disorder. Cerebral ischemic attacks, cognitive decline, strokes, and vascular dementia constitute the major manifestations of this disorder. This report details the prenatal detection of a Notch3 mutation in the fetus of a couple where the father had a known mutation in this gene. This is the first report of a prenatal diagnosis of CADASIL, and another example of a serious, highly penetrant, and relentlessly progressive degenerative genetic disorder presenting decades after birth and for which prenatal diagnosis is an option.

Abortion, Eugenic↗

Mutation analysis of the leucine-rich, glioma inactivated 1 gene (LGI1) in Japanese febrile seizure patients.

Mutations in the leucine-rich, glioma inactivated 1 gene (LGI1) were recently identified in some families with autosomal dominant lateral temporal epilepsy (ADLTE). To investigate whether the LGI1 gene is a susceptibility gene for febrile seizures (FS), we performed a systematic search for mutations in 94 unrelated Japanese patients with FS. We detected two intronic polymorphisms (IVS2 + 19 A/G and IVS6 - 18 T/C). No non-synonymous mutation was detected. We genotyped these polymorphisms and performed a case-control study and transmission disequilibrium testing (TDT) of 62 FS families (n = 230) and 105 control subjects. None of the polymorphisms was significantly associated with FS. Our results indicate that genomic variations in the LGI1 gene are not likely to be substantially involved in the etiology of FS in the Japanese population.

Alleles↗

Mutational analysis of polar amino acid residues within predicted transmembrane helices 10 and 16 of multidrug resistance protein 1 (ABCC1): effect on substrate specificity.

Human multidrug resistance protein 1 (MRP1) has a total of 17 transmembrane (TM) helices arranged in three membrane-spanning domains, MSD0, MSD1, and MSD2, with a 5 + 6 + 6 TM configuration. Photolabeling studies indicate that TMs 10 and 11 in MSD1 and 16 and 17 in MSD2 contribute to the substrate binding pocket of the protein. Previous mutational analyses of charged and polar amino acids in predicted TM helices 11, 16, and 17 support this suggestion. Mutation of Trp(553) in TM10 also affects substrate specificity. To extend this analysis, we mutated six additional polar residues within TM10 and the remaining uncharacterized polar residue in TM16, Asn(1208). Although mutation of Asn(1208) was without effect, two of six mutations in TM10, T550A and T556A, modulated the drug resistance profile of MRP1 without affecting transport of leukotriene C4, 17beta-estradiol 17-(beta-d-glucuronide) (E(2)17betaG), and glutathione. Mutation T550A increased vincristine resistance but decreased doxorubicin resistance, whereas mutation T556A decreased resistance to etoposide (VP-16) and doxorubicin. Although conservative mutation of Tyr(568) in TM10 to Phe or Trp had no apparent effect on substrate specificity, substitution with Ala decreased the affinity of MRP1 for E(2)17betaG without affecting drug resistance or the transport of other substrates tested. These analyses confirm that several amino acids in TM10 selectively alter the substrate specificity of MRP1, suggesting that they interact directly with certain substrates. The location of these and other functionally important residues in TM helices 11, 16, and 17 is discussed in the context of an energy-minimized model of the membrane-spanning domains of MRP1.

Antineoplastic Agents↗

Statistical and mutational analysis of chronic granulomatous disease in Japan with special reference to gp91-phox and p22-phox deficiency.

Chronic granulomatous disease (CGD) is a group of inherited disorders of host defense caused by a mutation in any of the four components of phagocyte NADPH oxidase, namely gp91-, p22-, p47-, and p67-phox. We have made a precise statistical analysis of 229 registered patients from 195 families in Japan and mutation analysis of 28 and 5 independent patients, respectively, with gp91- and p22-phox deficiency. The gp91- and p22-phox proteins form the membrane cytochrome b558, which plays important roles in the assembly of the active oxidase and electron-transfer reaction, and the lesions in either subunit account for more than 80% of cases. The ratio of male to female patients was 6.6/1, the incidence was calculated to be about 1 out of 220,000 birth, and the life expectancy of the patients born in the 1970s was estimated to be 25-30 years old. For the X-linked gp91-phox deficiency, we found five missense and nine nonsense mutations, seven deletions, three insertions, and four splice site mutations, which included the following novel mutations: four missense, five nonsense, six deletions, one insertion, and two splice site abnormalities. With regard to p22-phox deficiency, two homozygous nonsense mutations and one homozygous deletion, a missense mutation together with a splice site mutation, and two different missense mutations were found. These mutations have not been reported before. Based on the present and reported data from Japan, we discuss the molecular defects of the disease and the difference in statistics between western countries and Japan.

Base Sequence↗

Fibroblast growth factor receptor-2 mutation analysis in human prostate cancer.

OBJECTIVE: To assess whether mutations in the hot-spots of the fibroblast growth factor (FGF) receptor-2 gene (FGFR2, exons encoding the IIIa, IIIb, IIIc and transmembrane domain, TMD) are associated with the development of prostate cancer, as the IIIb variant is the specific receptor for FGF7/KGF, an androgen-inducible paracrine factor regulating prostatic growth. Materials and methods Single-strand conformational polymorphism-polymerase chain reaction (SSCP-PCR) and cycle-sequencing analysis were used to screen FGFR2 mutations in 30 patients with prostate cancer; corresponding blood samples were analysed from 11 of the patients. The human prostate cell lines, LNCaP, PC3, DU145, PNT1A and PNT1B were also examined. In addition, 10 foci of invasive cancer from three patients who underwent radical prostatectomy were also assessed. RESULTS: Positive controls containing FGFR2 mutations (Crouzon disease and Pfieffer syndrome) were confirmed by SSCP-PCR and sequencing. Analysis of all prostate tumour samples and prostate-derived cell lines revealed no polymorphisms or mutations in the IIIa, IIIb, IIIc and TMD regions of FGFR2. CONCLUSION: FGFR2 mutations in the-FGF binding domain and the TMD are not frequent events in human prostate cancer.

Cohort Studies↗

P53 mutation analysis of colorectal liver metastases: relation to actual survival, angiogenic status, and p53 overexpression.

PURPOSE: To correlate TP53 mutations with angiogenic status of the tumor and prognosis after liver surgery in patients with colorectal liver metastases and to correlate immunohistochemical staining of p53 protein with TP53 gene mutations. EXPERIMENTAL DESIGN: Tumors of 44 patients with surgically treated colorectal liver metastases were analyzed for (a) TP53 mutations using denaturing gradient gel electrophoresis followed by sequencing, (b) microvessel density using the hot spot overlap technique, (c) apoptotic rate in tumor cells and endothelial cells of tumor microvessels using double immunostaining for anti-cleaved caspase 3 and anti-CD34, and (d) expression of p53 protein using immunohistochemistry. RESULTS: TP53 mutations were detected in 36% of the metastases and occurred more frequently in liver metastases from left-sided colon tumors than from right-sided colon tumors (P = 0.04). In metastases with TP53 mutations, microvessel density was higher compared with tumors with wild-type p53. Endothelial cell apoptosis was not different in tumor microvessels from TP53-mutated versus nonmutated tumors. The 5-year actual survival was not influenced by TP53 mutational status, microvessel density, or endothelial cell apoptotic rate of the tumors. Based on immunohistochemical p53 overexpression, the positive and negative predictive values of TP53 mutations were 61% and 82%. CONCLUSIONS: In patients with surgically treated colorectal liver metastases, TP53 mutations and angiogenic status did not influence prognosis. Immunohistochemistry is not a reliable technique for detecting TP53 mutations.

Aged↗

Loss of heterozygosity and mutational analysis of the PTEN/MMAC1 gene in synchronous endometrial and ovarian carcinomas.

Mutations of the human putative protein tyrosine phosphatase (PTEN/MMAC1) gene at chromosome 10q23 have been found frequently in type I endometrial carcinomas. Endometrioid adenocarcinoma is the most frequent histology seen in patients with clinically determined synchronous endometrial and ovarian carcinomas. We report a high incidence of PTEN/MMAC1 mutations and 10q23 loss of heterozygosity (LOH) in patients with synchronous endometrial and ovarian carcinomas. Paraffin-embedded precision microdissected tumors were analyzed for 10 matched synchronous endometrial and ovarian cancers and 11 matched control metastatic endometrial cancers. Single-stranded conformation polymorphism analysis was used to screen for mutations in all tumors and corresponding normal lymphocyte DNA. LOH was determined using a panel of four microsatellite markers within the PTEN/MMAC1 locus. PTEN/MMAC1 mutations were found in 43% (9 of 21) of the endometrial cancers studied, similarly represented in the clinically synchronous group (5 of 10 or 50%) and the advanced metastatic group (4 of 11; 36%; P = 0.53). In two of the five cases of clinically synchronous cancers, identical or progressive PTEN mutations were found in both the endometrial and ovarian cancers, suggesting that the ovarian tumor is a metastasis from the endometrial primary. PTEN/MMAC1 mutations in the advanced endometrial cancers were similar in the corresponding metastases. In one case, the mutation was seen in only one of two metastatic lymph nodes. The LOH analysis demonstrated 55% LOH in at least one PTEN/MMAC1 marker. These findings suggest that the putative tumor suppressor gene PTEN/MMAC1 may be a viable molecular marker to differentiate synchronous versus metastatic disease in a subset of clinically synchronous endometrial and ovarian carcinomas.

Adult↗

[Mutation analysis of SRD5A2 gene in patients with hypospadias].

OBJECTIVE: To explore possible molecular mechanism of hypospadias and relationship of the mutation of SRD5A2 gene to hypospadias. METHODS: 96 blood samples from the patients with hypospadias were obtained and DNA was extracted from blood leukocytes. Polymerase chain reaction and direct sequencing were performed to analyze the coding regions of SRD5A2 gene. RESULTS: 8 mutations were detected from 14 cases, including 5 missense mutations, 1 synonymous mutation, 1 nonsense mutation and 1 frameshift mutation. The mutations are in 1st, 4th and 5th exon. Gln6stop, His232His, Phe234Leu and frameshift mutations are novel. CONCLUSIONS: Exon 4 is a hot spot region of mutation within SRD5A2 gene, and about 10 percent of hypospadiac patients complicated with SRD5A2 dysfunction or deficiency.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗

Linkage disequilibrium, mutational analysis and natural selection in the repetitive region of the clock gene, period, in Drosophila melanogaster.

We have used the method of disequilibrium pattern analysis to examine associations between the threonine-glycine (Thr-Gly) encoding repeat region of the clock gene period (per) of Drosophila melanogaster, and polymorphic sites both upstream and downstream of the repeat, in a number of European fly populations. The results are consistent with the view that selection may be operating on various haplotypes which share the Thr-Gly length alleles encoding 17, 20 and 23 dipeptide pairs, and that the repeat itself may be the focus for selection. These conclusions lend support to a number of other population and behavioural investigations which have provided evidence that selection is acting on the Thr-Gly region. The linkage analysis was also used to infer an approximate mutation rate (mu) for the repeat, of 10(-5) < mu < 4 x 10(-5) per gamete per generation. Direct measurements of the mutation rate using the polymerase chain reaction in a pedigree analysis of tens of thousands of individuals do not contradict this value. Consequently, the Thr-Gly repeat does not have a mutation rate that is as high as some of the non-coding minisatellites, but it is several orders of magnitude higher than the nucleotide substitution rate. The implications of this elevated mutation rate for linkage disequilibria and selection are discussed.

Alleles↗

Detection of cancerous endobronchial lesions by autofluorescence bronchoscopy combined with mutation analysis of p53.

Early lung cancer screening failed to reduce lung cancer mortality. New techniques such as autofluorescence bronchoscopy (AF) and the identification of specific genetic alteration might change future outcomes of lung cancer screening. It was the aim of our study to combine p53 analysis with white-light bronchoscopy (WL) or WL and AF to improve the diagnostic yield in a series of 36 patients with histologically proven lung cancer, pulmonary metastasis or suspected lung cancer. - Endobronchial sites were analysed by WL (n = 71), AF (Storz) (n = 34), histopathology (n = 71) and p53 mutations were examined by SSCP analysis on additional biopsies (n = 69). The overall frequency of cancerous lesions was 19, of which 14 were macroscopically visible lesions. The addition of p53 and autofluorescence improved the yield to 17 of 19 cases. In 7 preinvasive lesions (dysplasia/metaplasia) 4 were identified macroscopically and 5 of 7 lesions by all 3 methods. In the WL/p53 group the diagnostic yield was 7 of 9 cancerous lesions compared to 10 of 10 cancerous lesions in the AF group. It should be noted that all methods were associated with false positive results. However, the combination of conventional with autofluorescence bronchoscopy and mutation analysis is a promising approach which is applicable to clinical routine and may be further enhanced by the inclusion of a panel of markers of tumour progression.

Bronchoscopy↗

Mutation analysis of the HFE gene in Brazilian populations.

We analyzed the frequency of the C282Y and H63D mutations in the HFE gene in 227 individuals from Brazil comprising 71 Caucasians, 91 racially mixed Caucasian African-derived Amerindians (both populations from Southeast Brazil), 85 African-derived subjects (from Northeast Brazil) and 75 Parakanã Indians. Allelic frequency of the mutation C. 845G(A (C282Y) was 1.4% in the Caucasian population, 1.1% in the African-derived population, 1.1% in the racially mixed normal controls and 0% in the Parakanã Indians. In the African-derived population, the C282Y mutation was present on chromosomes bearing the haplotype 6/1h according to Beutler and West (1997). Allelic frequency of the mutation C. 187C(G (H63D) was 16.3% in the Caucasian population, 7.5% in the African-derived population, 9.8% in the racially mixed controls and 0% in the Amerindians. The presence of these mutations in the African-derived population reflects the fact that these subjects may have undergone a non-identified racial admixture in their past history. The absence of both defects in the Amerindians suggests that these mutations have emerged after the migration of Polynesians to America, or that they may not have reached the Polynesian population until after the migration to America had occurred.

Africa↗

Mutation analysis of PTPN11 in Noonan syndrome by WAVE.

The chapter details the methodology for polymerase chain reaction amplification and WAVE denaturing high-performance liquid chromatography (DHPLC) analysis for all coding exons for the gene PTPNI1, which is mutated in approx 50% of cases of Noonan Syndrome. Although DNA sequencing is initially required to determine the mutation(s) detected by WAVE (sequencing methods are not described in this chapter), each mutation has its own DHPLC signature, and experienced operatives can determine known mutations on this basis. The new Navigator software has made this process more reliable.

Chromatography, High Pressure Liquid↗

Mutational analysis of gene families in human cancer.

The completion of the human genome project has marked a new beginning in biomedical sciences. Human cancer is a genetic disease and, accordingly, the field of oncology has been one of the first to be impacted by this historic revolution. Knowledge of the sequence and organization of the human genome facilitates the systematic analysis of the genetic alterations underlying the origin and evolution of tumors. Recent mutational analyses in colorectal and other cancers have focused on examination of gene families involved in signal transduction, such as kinases and phosphatases. This approach has been successful in identifying mutations in a variety of different genes, including the identification of PI3KCA as one of the most commonly mutated oncogenes in human cancer. Such genomic analyses have already demonstrated their utility in basic and clinical cancer research, and are expected to have an important impact on future diagnostic and therapeutic strategies.

Colorectal Neoplasms↗

[Mutational analysis of BRCA1 and BRCA2 genes in early-onset breast cancer patients in Shanghai].

OBJECTIVE: To investigate the prevalence of BRCA1 and BRCA2 mutations among early-onset breast cancer patients in Shanghai. METHODS: Fifty patients unselected for family history, who were diagnosed with breast cancer before the age of 40 years were analyzed. Among them, 13 patients have at least one first-degree relative affected with breast cancer. Mutation screening of BRCA1 and BRCA2 was performed in the whole coding sequence through Denaturing High Performance Liquid Chromatography (DHPLC) and subsequent DNA direct sequencing. RESULTS: Six deleterious mutations, including 2 novel frameshift mutations (3449insA, 5587-1del8) and 2 novel splice-site mutations (IVS17-1G > T, IVS21 + 1G > C) in BRCA1 were identified. Two deleterious mutations detected in BRCA2, including one frameshift mutation (5950delCT) and one novel missense mutation (5911G > C), all occurring on exon 11 adjacently. Additional 12 novel sequence variants were also detected including one unclassified variant and 7 intronic variants in BRCA1, and 4 novel intronic variants in BRCA2, all causing no alteration of amino acid coding. The prevalence of BRCA1 and BRCA2 mutations in the patients with early-onset breast cancer was 12% and 4%, respectively. CONCLUSION: Four novel mutations in BRCA1 and one novel mutation in BRCA2 may be mutations characterized of early-onset breast cancer in Chinese population. Germline mutations in BRCA2 may contribute less than mutations in BRCA1 to early-onset breast cancer in Shanghai. These data contribute to information on spectrum of BRCA gene in Chinese population and also offer a recommended screening mode for clinical genetic testing programme in China.

BRCA1 Protein↗

Mutational analysis of TSC1 and TSC2 in Korean patients with tuberous sclerosis complex.

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by a broad phenotypic spectrum that includes seizures, mental retardation, renal dysfunction and dermatological abnormalities. TSC is caused by mutations affecting either of the tumor-suppressor genes TSC1 and TSC2. At least 495 mutations of TSC1 and TSC2 have been reported. Twenty-two males and 22 females who were diagnosed with TSC at the Seoul National University Children's Hospital between 1982 and 2002 were enrolled in the study. Forty-four patients were from different families and included nine familial cases and 35 sporadic cases. Denaturing high performance liquid chromatography and DNA sequencing analysis of TSC1 and TSC2 revealed 13 types of mutations (30%). One novel mutation of TSC1 and nine novel mutations of TSC2 were identified. The TSC1 mutation and one of the nine TSC2 mutations were missense mutations and seven of the nine TSC2 mutations caused truncation of proteins. One novel single nucleotide substitution was identified at the consensus splicing donor site of exon 39 (c.5,069-1G>A). This mutation is predicted to cause a splicing error. Of the TSC2 mutation loci, the correlation with cardiac rhabdomyoma was more significant when the mutation was in the C-terminal part of tuberin than the N-terminal part. This is the first extensive mutational analysis of TSC1 and TSC2 in Korean TSC patients.

Child, Preschool↗

Mutation analysis of Jagged1 (JAG1) in Alagille syndrome patients.

Alagille syndrome (AGS) is an autosomal dominant disorder caused by mutations in Jagged1 (JAG1), a ligand in the evolutionarily conserved Notch signaling pathway. Previous studies have demonstrated that a wide spectrum of JAG1 mutations result in AGS. These include total gene deletions, protein truncating, splicing and missense mutations which are distributed across the coding region of the gene. Here we present results of JAG1 mutation screening by SSCP and FISH in 105 patients with AGS. For these studies, new primers were designed for 12 exons. Mutations were identified in 63/105 patients (60%). The spectrum of the JAG1 mutations presented here is consistent with previously reported results. Eighty three percent (52/63) of the mutations were protein truncating, 11% (7/63) were missense, 2% (1/63) were splice site, and 5% (3/63) were total gene deletions demonstrable by FISH. Six of the missense mutations are novel. As has been reported previously, there is no apparent relationship between genotype and clinical phenotype.

Alagille Syndrome↗