<Emphasis Type="Italic">c-KIT</Emphasis> codon 816 mutation in a recurrent and metastatic dysgerminoma of a 14-year-old girl: case study

Dysgerminomas are rare female germ-cell tumors that correspond histologically and immunohistochemically to seminomas. Analogous to seminomas, most dysgerminomas respond very well to cisplatin- or carboplatin-based chemotherapy and to radiotherapy. KIT tyrosine kinase is crucial for normal germ-cell development, and its expression is observed in the majority of seminomas and dysgerminomas. Recently, activating KIT mutations were described in a panel of male germ-cell tumors [5, 10]. All mutations were localized in exon 17, encoding the second tyrosine kinase domain. Because receptor tyrosine kinase KIT might also be involved in the pathogenesis of dysgerminomas, we studied the expression and mutational status of a pure dysgerminoma, which was sent to our department for diagnostic reasons. The tumor revealed an exon 17 D816 V mutation in the c-KIT gene and strong KIT expression was found immunohistochemically. Clinically, the tumor was highly aggressive and resistant to carboplatin-based chemotherapy. Our case raises the question of whether exon 17 c-KIT mutations might be involved in the pathogenesis of dysgerminoma and whether exon 17 KIT mutations may predict aggressive and chemotherapy-resistant behavior of dysgerminomas.     

Repeat induced point mutation in two asexual fungi, <Emphasis Type="Italic">Aspergillus niger</Emphasis> and <Emphasis Type="Italic">Penicillium </Emphasis><Emphasis Type="Italic">chrysogenum</Emphasis>

Repeat induced point mutation (RIP) is a gene silencing mechanism present in fungal genomes. During RIP, duplicated sequences are efficiently and irreversibly mutated by transitions from C:G to T:A. For the first time, we have identified traces of RIP in transposable elements of Aspergillus niger and Penicillium chrysogenum, two biotechnologically relevant fungi. We found that RIP in P. chrysogenum has affected a large set of sequences, which also contain other mutations. On the other hand, RIP in A. niger is limited to only few sequences, but literally all mutations are RIP-like. Surprisingly, RIP occurred only in transposon sequences that have disrupted open reading frames in A. niger, a phenomenon not yet reported for other fungi. In both fungal species, we identified two sequences with strong sequence similarity to Neurospora crassa RID. RID is a putative DNA methyltransferase and the only known enzyme involved in the RIP process. Our findings suggest that both A. niger and P. chrysogenum either had a sexual past or have a sexual potential. These findings have important implications for future strain development of these fungi.     

Tracing origin of serrated adenomas with <Emphasis Type="Italic">BRAF</Emphasis> and <Emphasis Type="Italic">KRAS</Emphasis> mutations

Serrated neoplasm of the colorectum raised many as-yet unanswered issues. To characterize serrated neoplasia pathway, we investigated BRAF and KRAS mutations in 35 traditional serrated adenomas. BRAF exons 11 and 15, and KRAS exon 2 were amplified by polymerase chain reaction and directly sequenced. BRAF V599E mutation was found in 27 serrated adenomas (77.1%), and KRAS mutations were found in 3 (8.6%) of 35 traditional serrated adenomas. In 13 cases, mixed polyps composed of traditional serrated adenomas and hyperplastic (serrated) polyps were observed, and seven of them showed the same BRAF mutations in both components. Somatic mutations of BRAF and KRAS genes were mutually exclusive. These findings suggest that BRAF mutations are early and a critical event in the serrated adenomas, and most serrated adenomas in both sides of colon may progress from microvesicular hyperplastic polyps via BRAF mutations, and some left-sided serrated adenomas develop via KRAS mutations.     

Diffuse Large B Cell Lymphoma in Hyper-IgE Syndrome Due To <Emphasis Type="Italic">STAT3</Emphasis> Mutation

The Job or hyper-immunoglobulinemia E syndrome is a primary immunodeficiency that is usually inherited in an autosomal dominant fashion. With the discovery of mutations in the STAT3 gene in the majority of autosomal dominant cases, it is now possible to make a molecular diagnosis of hyper-IgE syndrome. Both primary and secondary immunodeficiencies, including hyper-IgE syndrome, may predispose for malignancies, especially lymphomas, mainly mature B cell lymphomas, and classical Hodgkin lymphoma. Here, we report of a 48-year-old male with hyper-IgE syndrome who developed a primary parotid gland diffuse large B cell lymphoma. Analysis for STAT3 mutations demonstrated that the causal mutation of hyper-IgE syndrome, R382Q, arose de novo in the patient and it was transmitted to three of his five children, all three of whom are clinically affected. We review the literature regarding lymphoma in hyper-IgE syndrome and the possible etiologic relationship with STAT3 mutations.     

No variation in the prevalence of point mutations in the <Emphasis Type="Italic">Pfcrt</Emphasis> and <Emphasis Type="Italic">Pfmdr1</Emphasis> genes in isolates from Gabonese patients with uncomplicated or severe <Emphasis Type="Italic">Plasmodium falciparum</Emphasis> malaria

In Lambaréné (Gabon), where a high level of Plasmodium falciparum resistance to chloroquine has been reported, we assessed the relationship between polymorphisms in the P. falciparum chloroquine resistance transporter (Pfcrt) and multidrug resistance-1 (Pfmdr1) genes and the clinical severity of malaria. Ninety-one and 60 P. falciparum isolates from children with uncomplicated or severe malaria were collected in 1996 and 2002, respectively. Single nucleotide mutations at codon 76 in the Pfcrt gene and at codons 86, 184, 1034, 1042, and 1246 in the Pfmdr1 gene were assessed by PCR-RFLP. All P. falciparum isolates presented the Pfcrt K76T mutation, whatever the clinical status. A high prevalence (>80%) of the Pfmdr1 86Tyr and 184Phe mutations was detected at both time points and in both clinical groups. We did not identify any specific mutation in the Pfmdr1 gene associated with the severity of disease, and the multiplicity of P. falciparum infection was also similar in both groups. Our results showed no change in the polymorphism of Pfcrt and Pfmdr1 genes in P. falciparum isolates collected in 1996 and 2002, and the severity of the disease was not associated with specific mutations neither in the Pfcrt nor in the Pfmdr1 genes in the study site.     

High prevalence of germline <Emphasis Type="Italic">STK11</Emphasis>mutations in Hungarian Peutz-Jeghers Syndrome patients

Background  

Peutz-Jeghers syndrome (PJS) is a rare autosomal dominantly inherited disease characterized by gastrointestinal hamartomatous polyposis and mucocutaneous pigmentation. The genetic predisposition for PJS has been shown to be associated with germline mutations in the STK11/LKB1 tumor suppressor gene. The aim of the present study was to characterize Hungarian PJS patients with respect to germline mutation in STK11/LKB1 and their association to disease phenotype.     

The impact of CFNS-causing <Emphasis Type="Italic">EFNB1</Emphasis> mutations on ephrin-B1 function

Background  

Mutations of EFNB1 cause the X-linked malformation syndrome craniofrontonasal syndrome (CFNS). CFNS is characterized by an unusual phenotypic pattern of inheritance, because it affects heterozygous females more severely than hemizygous males. This sex-dependent inheritance has been explained by random X-inactivation in heterozygous females and the consequences of cellular interference of wild type and mutant EFNB1 -expressing cell populations. EFNB1 encodes the transmembrane protein ephrin-B1, that forms bi-directional signalling complexes with Eph receptor tyrosine kinases expressed on complementary cells. Here, we studied the effects of patient-derived EFNB1 mutations predicted to give rise to truncated ephrin-B1 protein or to disturb Eph/ephrin-B1 reverse ephrin-B1 signalling. Five mutations are investigated in this work: nonsense mutation c.196C > T/p.R66X, frameshift mutation c.614_615delCT, splice-site mutation c.406 + 2T > C and two missense mutations p.P54L and p.T111I. Both missense mutations are located in the extracellular ephrin domain involved in Eph-ephrin-B1 recognition and higher order complex formation.     

A novel nuclear marker,Pm-int9, for phylogenetic studies of <Emphasis Type="Italic">Opisthorchis felineus</Emphasis>, <Emphasis Type="Italic">Opisthorchis viverrini</Emphasis>, and <Emphasis Type="Italic">Clonorchis sinensis</Emphasis> (Opisthorchiidae,Trematoda)

Opisthorchis felineus, O. viverrini, and Clonorchis sinensis, the trematodes of the family Opisthorchiidae, are important human parasites. Two previous studies (Kang et al. Parasitol Int 57:191–197, 2008; Katokhin et al. Dokl Biochem Biophys 421:214–217, 2008) have provided evidence using ribosomal and mitochondrial sequences that O. viverrini, O. felineus, and C. sinensis are closely related. We developed a novel nuclear marker, Pm-int9, which included the ninth intron of the paramyosin gene and flanking exon sequences. Samples of O. felineus from four localities of West Siberia, C. sinensis from the Russian Far East, and O. viverrini from Thailand were genotyped by Pm-int9. Little variation was detected in exon sequences, however, intron sequences turned out to be more variable than ribosomal internal transcribed spacers. We can conclude that Pm-int9 is valuable for interspecific variation studies. Phylogenetic analysis based on Pm-int9 revealed that O. viverrini and C. sinensis were closer to each other than either of them to O. felineus, supporting the opinion that C. sinensis should be considered the sister species of Opisthorchis spp.     

Mutational analysis of<Emphasis Type="Italic"> BRAF</Emphasis> in gallbladder carcinomas in association with<Emphasis Type="Italic"> K-ras</Emphasis> and<Emphasis Type="Italic"> p53</Emphasis> mutations and microsatellite instability

Background Little is known about the genetic changes involved in the pathogenesis of gallbladder cancer. The aim of this study was to examine the presence of mutations in exon 15 of the B-raf gene to investigate its role in gallbladder carcinogenesis.Materials and methods We examined the mutational status in exon 15 of B-raf gene in 21 gallbladder carcinoma specimens and investigated its association with the presence of K-ras and p53 alterations, microsatellite instability and the clinicopathological features of tumors.Results B-raf mutations were observed in 7 of 21 (33%) gallbladder carcinomas examined, and all were located at the hot spot codon 599 of exon 15. K-ras and B-raf mutations were never in the same specimens.Conclusions B-raf gene mutations seem to be a quite common event in gallbladder carcinomas, implying that B-raf may play an important role in the pathogenesis of this tumor.     

Liver cancer with concomitant <Emphasis Type="Italic">TP53</Emphasis> and <Emphasis Type="Italic">CTNNB1</Emphasis> mutations: a case report

Background

In the spectrum of molecular alterations found in hepatocellular carcinoma (HCC), somatic mutations in the WNT/β-catenin pathway and the p53/cell cycle control pathway are among the most frequent ones. It has been suggested that both mutations occur in a mutually exclusive manner and they are used as molecular classifiers in HCC classification proposals.

Case presentation

Here, we report the case of a treatment-naïve mixed hepatocellular/cholangiocellular carcinoma (HCC/CCC) with morphological and genetic intratumor heterogeneity. Within the predominant part of the tumor with hepatocellular differentiation, a p.D32V mutation in exon 3 of the CTNNB1 gene occurred concomitantly with a TP53 intron 7/exon 8 splice site mutation.

Conclusion

Intratumor heterogeneity challenges the concept of CTNNB1 and TP53 gene mutations being mutually exclusive molecular classifiers in HCC, which has implications for HCC classification approaches.

     

Clinical and genetic analysis of <Emphasis Type="Italic">HLXB9</Emphasis> gene in Korean patients with Currarino syndrome

Currarino syndrome (CS) is a rare autosomal dominant disease that has been described as a triad of partial sacral agenesis, anorectal anomalies, and a presacral mass. Mutations in the HLXB9 gene have been suggested to be the genetic background of CS. In this study, sequence analysis of the HLXB9 gene was performed in two familial and two sporadic Korean patients showing the clinical features of CS, and two mutations in the HLXB9 gene were identified only in the two familial cases. One mutation (R295W) has been reported previously, and the other (H260_Q261delinsLELLELE) is novel. Consistent with previous observations, the phenotypic expression of the mutation carriers in the CS families varies from mild to severe, including the complete triad. This study confirms that familial CS patients in Korea have the same genetic background as other ethnicities and reaffirms the phenotype variability among CS patients with the same mutation.     

A subset of colorectal carcinomas express c-KIT protein independently of <Emphasis Type="Italic">BRAF</Emphasis> and/or <Emphasis Type="Italic">KRAS</Emphasis> activation

c-KIT is a tyrosine kinase receptor found to be overexpressed in several tumours, namely, GISTs, breast, lung, prostate, ovarian and colorectal carcinomas (CRC). We aimed at determining the frequency of c-KIT expression and mutations in a series of 109 CRC cases (73 primary tumours and 36 lymph node metastases) characterised for KRAS and BRAF mutations. We also aimed at analysing the cellular effects of STI571/Gleevec in CRC-derived cell lines displaying c-KIT expression and KRAS or BRAF mutations. By immunohistochemistry, we found c-KIT overexpression in 15% (11/73) of primary tumours and in 14% (5/36) of metastasis; however, cases showing overexpression did not show c-kit mutations in hotspot regions. The majority (64%) of primary tumours with c-KIT overexpression had mutations at KRAS–BRAF genes. The same was true for 60% of the metastases. We treated CRC cell lines with STI571/Gleevec and verified that it inhibits proliferation and induces apoptosis in all cell lines. In conclusion, overexpression of c-KIT is observed in a subset of primary and CRC metastases in the absence of c-kit mutations. STI571/Gleevec increases apoptosis in CRC cell lines independently of its genetic profile, suggesting that STI571/Gleevec is likely to be an alternative drug for the clinical trials of CRC.     

Prevalence of the <Emphasis Type="Italic">GJB2</Emphasis> IVS1+1G >A mutation in Chinese hearing loss patients with monoallelic pathogenic mutation in the coding region of <Emphasis Type="Italic">GJB2</Emphasis>

Background  

Mutations in the GJB2 gene are the most common cause of nonsyndromic recessive hearing loss in China. In about 6% of Chinese patients with severe to profound sensorineural hearing impairment, only monoallelic GJB2 mutations known to be either recessive or of unclear pathogenicity have been identified. This paper reports the prevalence of the GJB2 IVS1+1G>A mutation in a population of Chinese hearing loss patients with monoallelic pathogenic mutation in the coding region of GJB2.     

<Emphasis Type="Italic">KNQ1</Emphasis>, a<Emphasis Type="Italic"> Kluyveromyces lactis</Emphasis> gene encoding a drug efflux permease

Several transport systems play an important role in conferring multiple drug resistance, presumably due to their catalysis of the energy-dependent extrusion of a large number of structurally and functionally unrelated compounds out of the cells. In the present work, the gene named KNQ1 (encoding Kluyveromyces lactis membrane permease) was cloned by functional complementation of the cycloheximide-hypersensitivity phenotype of the Saccharomyces cerevisiae mutant strain lacking a functional PDR5 gene. The isolated gene exhibited 48.9% identity with the S. cerevisiae ATR1 gene conferring resistance to aminotriazole and 4-nitroquinoline-N-oxide and encoded a protein of 553 amino acids. When present in multicopy, it efficiently complemented the phenotype associated with the pdr5 or pdr1pdr3 mutations in S. cerevisiae. Overexpression of the KNQ1 gene in K. lactis wild-type strains led to resistance against several cytotoxic compounds, like 4-nitroquinoline-N-oxide, 3-aminotriazole, bifonazole and ketoconazole. The gene was assigned to K. lactis chromosome III and its expression was found to be responsive to oxidative stress induced by hydrogen peroxide. Based on the phenotype of homologous and heterologous transformants, we propose that the gene encodes a membrane-associated component of the machinery responsible for decreasing the concentration of several toxic compounds in the cytoplasm of yeast cells.Communicated by K. Breunig     

Use of pyrosequencing to identify point mutations in domain V of 23S rRNA genes of linezolid-resistant <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> and <Emphasis Type="Italic">Staphylococcus epidermidis</Emphasis>

A pyrosequencing assay was used for the rapid characterization of linezolid-resistant isolates of Staphylococcus aureus and Staphylococcus epidermidis. The assay identified base substitutions in copies of the 23S rRNA gene and determined the percentage of alleles with the mutation. Modifications of the assay were necessary to identify all mutations in the 23S rRNA genes of S. epidermidis that were associated with linezolid resistance. A C2534T mutation was identified in S. epidermidis that was not previously reported in a linezolid-resistant isolate.     

DNA repair and recombination functions in <Emphasis Type="Italic">Arabidopsis</Emphasis> telomere maintenance

In this review, we discuss recent advances in the knowledge of plant telomere maintenance, focusing on the model plant Arabidopsis thaliana and, in particular, on the roles of proteins involved in DNA repair and recombination. The question of the interrelationships between DNA repair and recombination pathways and proteins with telomere function and maintenance is of increasing interest and has been the subject of a number of recent reviews (Cech 2004, d’Adda di Fagagna et al. 2004, Hande 2004, Harrington 2004, Maser & DePinho 2004). Understanding of telomere biology, DNA repair and recombination in plants has rapidly progressed over the last decade, substantially due to genetic approaches in Arabidopsis, and we feel that this is an appropriate time to review current knowledge in this field. A number of recent reviews have dealt more generally with the subject of plant telomere structure and evolution (Riha et al. 2001, McKnight et al. 2002, Riha & Shippen 2003b, McKnight & Shippen 2004, Fajkus et al. 2005) and we thus focus specifically on plant telomere biology in the context of DNA repair and recombination in Arabidopsis.     

Impact of a mutation in the mitochondrial <Emphasis Type="Italic">LSU rRNA</Emphasis> gene from <Emphasis Type="Italic">Chlamydomonas reinhardtii</Emphasis> on the activity and the assembly of respiratory-chain complexes

Two substitutions A1090G and A1098C (together called the m mutation) located in the conserved GTPase domain of the mitochondrial LSU rRNA gene were recently shown to weakly compensate for the phenotypical effect of a –1T frameshift mutation in the mitochondrial cox1 gene of C. reinhardtii. In order to analyze the impact of the m mutation on the mitochondrial translational machinery, a strain carrying the m mutation but wild-type for the cox1 gene was isolated. We found that the growth and the respiratory rate of the m mutant were affected and that the activities of complexes I, III, and IV, all containing mitochondria-encoded subunits, were lowered. In contrast the activities of complex II and of the alternative oxidase, both encoded exclusively by the nuclear genome, were not modified. The steady-state levels of complex I enzyme and of several components of the respiratory complexes I, III, and IV were also reduced in the mutant. We moreover showed that m did not suppress other frameshift or UGA stop mutations which affect mitochondrial genes.     

An association study on contrasting cystic fibrosis endophenotypes recognizes <Emphasis Type="Italic">KRT8</Emphasis> but not <Emphasis Type="Italic">KRT18</Emphasis> as a modifier of cystic fibrosis disease severity and CFTR mediated residual chloride secretion

Background  

F508del-CFTR, the most frequent disease-causing mutation among Caucasian cystic fibrosis (CF) patients, has been characterised as a mutant defective in protein folding, processing and trafficking. We have investigated the two neighbouring cytokeratin genes KRT8 and KRT18 in a candidate gene approach to ask whether variants in KRT8 and/or KRT18 modify the impaired ion conductance known as the CF basic defect, and whether they are associated with correct trafficking of mutant CFTR and disease severity of CF.     

Description of <Emphasis Type="Italic">Sarcocystis anasi</Emphasis> sp. nov. and <Emphasis Type="Italic">Sarcocystis albifronsi</Emphasis> sp. nov. in birds of the order Anseriformes

On the basis of the already published morphological, 18S rDNA, 28S rDNA data (Kutkienė et al., Parasitol Res 99:562–565, 2006; Parasitol Res 102:691–696, 2008; Parasitol Res 104:329–336, 2009), and ITS-1 region investigation results of sarcocysts presented in this paper, Sarcocystis albifronsi sp. nov. from the white-fronted goose (Anser albifrons) and Sarcocystis anasi sp. nov. from the mallard duck (Anas platyrhynchos) are described.     

<Emphasis Type="Italic">SLC2A10</Emphasis> genetic polymorphism predicts development of peripheral arterial disease in patients with type 2 diabetes. <Emphasis Type="Italic">SLC2A10</Emphasis>and PAD in type 2 diabetes

Background  

Recent data indicate that loss-of-function mutation in the gene encoding the facilitative glucose transporter GLUT10 (SLC2A10) causes arterial tortuosity syndrome via upregulation of the TGF-β pathway in the arterial wall, a mechanism possibly causing vascular changes in diabetes.