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PubMed2006

Dissection of mitochondrial superhaplogroup H using coding region SNPs.

Haplogroup H (hg H) includes about 40-50% of the West Eurasian mitochondrial DNA (mtDNA) samples investigated so far. In order to enhance discrimination within this haplogroup we selected 45 coding region SNPs that allow to ascribe samples to the main phylogenetic branches of super hg HV (that embraces hg H) and, in particular, to H sublineages with a much finer resolution than previous studies. SNP selection was carried out using the most up-to-date available literature on population and forensic genetics and extended by means of phylogenetic analysis of complete or coding region genomes (<430) and control region sequences. A meticulous inspection of the H phylogeny led us to the observation of various but uncharacterized subclades of hg H. The selected SNPs were amplified in two PCR-multiplex reactions and subsequently targeted in three single-base extension multiplex reactions. A total of 2214 West Eurasian samples were screened for hg H specific loci 2706 and 7028, of which 859 fell in hg H and were further subjected to subhaplogroup typing. We observed 35 different subhaplogroups in total, 33 of which were found at frequencies below 5%. This assay can be used as a prescreening tool in forensic casework for rapid discrimination between divergent lineages (very effective for high-volume crime cases) or as discriminatory assay, when identical hg H haplotypes were obtained by control region sequencing.

Adolescent↗

PubMed2006

Evaluation of whole-genome amplification of low-copy-number DNA in chimerism analysis after allogeneic stem cell transplantation using STR marker typing.

Whole-genome DNA amplification (WGA) is a promising method that generates large amounts of DNA from samples of limited quantity. We investigated the accuracy of a multiplex PCR approach to WGA over STR loci. The amplification bias within a locus and over all analyzed loci was investigated in relation to the amount of template in the WGA reaction, the specific STR locus, and allele length. We observed reproducible error-free STR profiles with 10 ng down to 1 ng of DNA template. The amplification deviation at a locus and between loci was within the intra-method reproducibility. WGA is the method of choice for amplifying nanogram amounts of genomic DNA for different applications. We detected unbalanced STR amplifications at one locus and between loci, allelic drop-outs, and additional alleles after WGA of low-copy-number DNA. We found that the high number of drop-outs and drop-ins could be eradicated using pooled DNA from separate WGA reactions even with as little as 100 pg of starting template. Nevertheless, the quality of the results was still not sufficient for use in routine chimerism analysis of limited specific cell populations after allogeneic stem cell transplantation.

Chimerism↗

PubMed2003

Variability in human sensitivity to 1,3-butadiene: Influence of the allelic variants of the microsomal epoxide hydrolase gene.

The carcinogenic effects of 1,3-butadiene (BD), a chemical widely used in the rubber industry, are thought to be due to its epoxide metabolites. In humans, these epoxides are detoxified predominantly by hydrolysis, a reaction mediated by the microsomal epoxide hydrolase (mEH) enzyme. The mEH gene is polymorphic and the most common mEH coding-region variants detected in human populations are the two amino acid polymorphisms Tyr113His and His139Arg. Polymorphic amino acid substitutions at residues 113 and 139 in the human mEH protein can associate in four distinct combinations: Tyr113/His139, Tyr113/Arg139, His113/His139, and His113/Arg139. In vitro studies have shown that each of these genotypes has a unique mEH protein level that can affect net mEH enzymatic activity. In the current study, we examined the relationships among the genotypes involving these two polymorphisms and the mutagenic responses associated with occupational exposure to BD. We studied 49 nonsmoking workers from two styrene-butadiene rubber facilities in southeast Texas using the autoradiographic HPRT mutant lymphocyte assay as a biomarker of genotoxic effect. We genotyped the study participants simultaneously for both polymorphisms, using a multiplex PCR assay developed in our laboratory, and the subjects were assigned to a specific group based on the predicted mEH activity associated with their genotypes (low, intermediate, and high). In the study population, 67% were exposed to low BD levels of <150 ppb (measured by personal badge dosimeters) and 33% were exposed to >150 ppb (mean 2,244 ppb). In the BD low-exposure group, the mEH genotypes had no significant effect on the HPRT variant (mutant) frequency (Vf). In the high-exposure group (BD > 150 ppb), individuals with genotypes associated with low mEH activity had a significant (P < 0.05) 3-fold increase in HPRT Vf (Vf +/- SEM = 13.95 +/- 2.15 x 10(-6)) compared to high-activity individuals (4.41 +/- 1.19 x 10(-6)), and a 2-fold increase in Vf compared to intermediate-activity individuals (6.44 +/- 2.09 x 10(-6)). Our results indicate that mEH genotypes may play a significant role in human sensitivity to the genotoxic effects of exposure to BD.

Alleles↗

PubMed2001

Gene- and tissue-specificity of mutation in Big Blue rats treated with the hepatocarcinogen N-hydroxy-2-acetylaminofluorene.

In a previous study, we found that treating transgenic Big Blue rats with the hepatocarcinogen N-hydroxy-2-acetylaminofluorene (N-OH-AAF) produced the same major DNA adduct in the target liver and the nontarget spleen lymphocytes and bone marrow cells, induced lacI mutants in the liver, and induced much lower frequencies of lacI and hprt mutants in spleen lymphocytes. In the present study, sequence analysis was conducted on lacI DNA and hprt cDNA from the mutants, to determine the mutational specificity of N-OH-AAF in the rat. All the mutation spectra from N-OH-AAF-treated rats differed significantly from corresponding mutation profiles from untreated animals (P = 0.02 to P < 0.0001). Although there were similarities among the mutational patterns derived from N-OH-AAF-treated rats (e.g., G:C --> T:A transversion was the most common mutation in all mutation sets), there were significant differences in the patterns of basepair substitution and frameshift mutation between the liver and spleen lymphocyte lacI mutants (P = 0.02) and between the spleen lymphocyte lacI and hprt mutants (P = 0.04). Also, multiplex PCR analysis of genomic DNA from the hprt mutants indicated that 12% of mutants from treated rats had major deletions in the hprt gene; no corresponding incidence of large deletions was evident among lacI mutations. All the mutation profiles reflect the general mutational specificity of the major DNA adduct formed by N-OH-AAF. The differences between N-OH-AAF mutation in the endogenous gene and transgene can be partially explained by the structures of the two genes. The tissue-specificity of the mutation spectra may contribute to targeting tumor formation to the liver. Environ. Mol. Mutagen. 37:203-214, 2001. Published 2001 Wiley-Liss, Inc.

Animals↗

PubMed2001

Nitric oxide donors induce large-scale deletion mutations in human lymphoblastoid cells: implications for mutations in T-lymphocytes from arthritis patients.

Rheumatoid arthritis (RA) is an inflammatory disease in which high levels of reactive nitrogen oxygen species (RNOS) may be present in the affected joints. RNOS are known to produce small-scale mutational events (transitions, transversions, small insertions, and small deletions) but the ability of these compounds to cause deletion of large segments of genomic DNA has not been previously determined. To address this question, a human lymphoblastoid cell line (WIL2-NS) was exposed to nitric oxide (NO)-donating drugs and hypoxanthine phosphoribosyltransferase (hprt)-negative clones were selected and analyzed by multiplex-PCR. Large-scale deletions accounted for 60-80% of hprt mutations arising in drug-treated cultures compared to 12% in untreated cultures (P-values of 0.006 and 0.0001, respectively, in two experiments). Deletion mutations in untreated cultures affected exon 9, whereas 75% of drug-induced deletion mutations affected exons 2, 3, and 9, and the remainder were very large, ranging from 26 to 1200 kbp. To compare this spectrum of NO-induced mutations in a lymphoblastoid line to that arising in vivo in arthritis patients, T-cells from RA patients, osteoarthritis (OA) patients, and controls were cloned and similarly analyzed. We previously showed that the overall frequency of Hprt mutant clones from patients is appreciably elevated compared to that of control subjects. Large-scale hprt deletions (0.5 to >26 kb) were detected in mutant T-cell clones from both RA and OA patients and also from control subjects. A total of 54 mutant clones from 16 RA patients and 19 mutant clones from 6 OA patients were studied. Of these, 6 clones (from 3 RA and 1 OA patient) had suffered large-scale deletions. A total of 9 control subjects were studied and 62 mutant clones were obtained. Of these, 19 had suffered large-scale deletions, arising in 7 of 9 control subjects. In conclusion, (1) RNOS are capable of inducing large-scale deletion mutations in a human lymphoblastoid cell line and (2) large-scale deletion mutations were found in 10-30% of T-cell clones from RA and OA patients and controls, which we hypothesize may be induced by RNOS.

Arthritis↗

PubMed1993

Spectrum of spontaneous HPRT- mutations in TK6 human lymphoblasts.

The occurrence of deletions, coding sequence alterations, and intronic changes leading to aberrant splicing has been characterized among 33 spontaneous HPRT- mutants in TK6 human lymphoblasts. Deletions detectable by multiplex PCR amplification accounted for 45% (15/33) of the mutant collection. Base substitutions represented 30% (10/33) of the total, and were predominated by changes at G:C base pairs. The remaining mutants were distributed among frameshifts (9%, 3/33), small deletions (6%, 2/33), and compound alterations (9%, 3/33). Five mutants (15%) demonstrated aberrant splicing of the hprt transcript. A cluster of 4 deletion/insertion events was identified in hprt exon 6. A nearly perfect 13 bp duplication differed from the original sequence only by an A:T to G:C transition, which was observed as a unique alteration in another HPRT- mutant. A model involving correction of a mismatch in a secondary structure formed by the duplicated sequence may account for these results.

B-Lymphocytes↗

PubMed2002

Comprehensive allelotyping of well-differentiated human hepatocellular carcinoma with semiquantitative determination of chromosomal gain or loss.

Allelic imbalance (AI), which represents certain chromosomal gains or losses, has been described in human hepatocellular carcinoma (HCC), but the impact of AI on the early stage of hepatocarcinogenesis has not been fully clarified. Moreover, no previous allelotype studies have identified the difference in chromosomal gain and loss that results in AI. To resolve these problems, we examined 18 well-differentiated HCCs with comprehensive allelotyping by using 400 microsatellite markers with semiquantitative assessment of chromosomal gain or loss. To detect allelic gain effectively, the cutoff value of the allelic imbalance index was set at 0.70. Each allele showing imbalance was subjected to multiplex PCR with use of a retained allele as an internal control to determine whether the imbalance was the result of chromosomal gain or loss. High frequencies of chromosomal gains were detected at 1q (D1S196-D1S2785, 56%), 5q (D5S647-D5S2027, 44%), 6p (6pter-D6S309, 33%), 7 (7pter-D7S657, 22%), and 8q (D8S514-qter, 44%), whereas chromosomal losses were frequently observed at 1p (1pter-D1S234, 22%), 8p (8pter-D8S549, 44%), and 17p (17pter-D17S921, 28%). The extent of overall chromosomal aberration was closely related to the maximum tumor diameter (P = 0.002) and the presence of hepatitis B surface antigen (P = 0.03). Recurrent chromosomal losses at 1p and 8p and gains at 1q and 8q, even in HCCs with a minimal extent of aberrant chromosomes, indicate that these alterations were critical in the early stage of hepatocarcinogenesis. On the other hand, deletions of 13q and 16q were infrequent and were seen only in the most aberrant cases, which suggested that these were late events.

Aged↗

PubMed2005

Discrete breakpoint mapping and shortest region of overlap of chromosome arm 1q gain and 1p loss in human hepatocellular carcinoma detected by semiquantitative microsatellite analysis.

Recurrent chromosomal gain at 1q is one of the most common features of human hepatocellular carcinoma (HCC), but how the gain at 1q contributes to hepatocarcinogenesis is still unclear. To identify the target genes, precise determination of the shortest region of overlap (SRO) and of breakpoints is necessary. Similarly, the role of loss at 1p, which is also a major cytogenetic aberration in HCC, needs to be determined. Fifty HCCs were examined with the aid of 59 microsatellite markers distributed throughout both arms of chromosome 1. To detect allelic gain effectively, the cutoff value of the allelic imbalance index was set at 0.70. Alleles showing imbalance were subjected to multiplex PCR, using a retained allele as an internal control, to determine whether the imbalance was the result of chromosomal gain or loss. The SRO of the gains was defined as D1S2878-D1S2619 (1q23.-q25.3, 16.9 Mb), which involved 36 cases (72%). Gains in the number of copies of certain oncogenes within this region seemed to be critical for the pathogenesis of HCC. In contrast, the centromeric breakpoints of these gains varied, but they tended to occur mainly in the pericentromeric region (26 of 50 cases, 52%). Rearrangement of specific genes associated with the gains is unlikely. On the other hand, the SRO of deletion was defined as D1S2893-D1S450 (1p36.32-p36.22, 5.1 Mb). Four known putative tumor-suppressor genes (TP73, RIZ1, NBL1/DAN, and CDKN2C) were outside the SRO, suggesting the presence of other candidate genes with critical roles in hepatocarcinogenesis.

Allelic Imbalance↗

PubMed2005

Prevalence of five previously reported and recurrent BRCA1 genetic rearrangement mutations in 20,000 patients from hereditary breast/ovarian cancer families.

Many rearrangement mutations in the BRCA1 gene have been identified. It is becoming clear that some of these mutations are prevalent, and therefore their detection is necessary in order for clinical genetic tests to have high sensitivity. Published information on particular rearrangements is frequently limited to a single patient, small groups of patients, or patients of a particular ethnicity. The objectives of this work included characterizing the prevalence of five specific rearrangement mutations in a large North American patient population. A mutation-specific multiplex PCR assay was used for determining the prevalence of five BRCA1 rearrangement mutations that previously had been reported to occur in unrelated patients. The mutation status of these rearrangements, which came from 20,712 patients at high risk for hereditary breast and/or ovarian cancers who had submitted specimens for clinical genetic testing, is presented. The results, obtained from 2,634 mutation carriers, showed a 6-kb duplication of exon 13, identified in 53 patients (2.01%); a 26-kb deletion encompassing exons 14-20, detected in seven patients (0.27%); a 510-bp deletion of exon 22, detected in 5 patients (0.19%); and a 3.4-kb deletion of exon 13, detected in one patient (0.04%). A previously reported 7.1-kb deletion of exons 8-9 was not found. The high frequency of the exon 13 duplication makes it the fourth most prevalent mutation in these patients. These results provide an accurate picture of the prevalence of these mutations in hereditary breast/ovarian cancer patients undergoing genetic testing in North America.

Breast Neoplasms↗

PubMed2006

Contribution of the BOP1 gene, located on 8q24, to colorectal tumorigenesis.

The most common form of genomic instability observed in colorectal cancer is chromosomal instability (CIN), whose molecular bases remain to be determined. We have previously demonstrated that inactivation in human cells of several components of the Pes1-Bop1 complex (BOP1, GRWD1, PES1, ORC6L, and RPL3), involved in ribosome biogenesis, altered chromosome segregation. To determine the contribution to colorectal tumorigenesis of somatic alterations of genes involved in ribosome biogenesis, we screened 56 primary colorectal cancers, using quantitative multiplex PCR of short fluorescent fragments, a sensitive method for the detection of gene dosage alterations. We found that dosage increase of the BOP1 gene was a frequent event, being detected in 39% of the tumors, and we show that it is associated with an increase of BOP1 mRNA. Scanning of 8q24, on which BOP1 is located, revealed that in colorectal cancers, gene dosage increase of BOP1 can be independent from that of MYC and was more frequent than that affecting MYC. Finally, transient overexpression of BOP1 in human cells increased the percentage of multipolar spindles. Together with our previous results, the present study strongly suggests that deregulation of the BOP1 pathway contributes to colorectal tumorigenesis.

Chromosomes, Human, Pair 8↗

PubMed2004

Comprehensive screening for constitutional RB1 mutations by DHPLC and QMPSF.

Constitutional mutations of the RB1 gene are associated with a predisposition to retinoblastoma. It is essential to identify these mutations to provide appropriate genetic counseling in retinoblastoma patients, but this represents an extremely challenging task, as the vast majority of mutations are unique and spread over the entire coding sequence. Since 2001, we have implemented RB1 testing on a routine basis as part of the clinical management of retinoblastoma. As most screening techniques do not meet the requirements for efficient RB1 testing, we have devised a semi-automated denaturing high-performance liquid chromatography (DHPLC) method for point mutation detection combined with a quantitative multiplex PCR of short fluorescent fragments (QMPSF) approach to screen for gene rearrangements. We report the results of this comprehensive screening of all exons and promoter of RB1 in 192 unrelated patients, mostly of French origin. Among 102 bilateral and/or familial cases and 90 unilateral sporadic probands, mutations were identified in 83 (81.5%) and 5 (5.5%) cases, respectively. A total of 43 mutations have not been previously reported. The mutational spectrum was found to be significantly different from previous published series, displaying a surprising amount of splice mutations and large deletions. This study demonstrates the reliability of DHPLC for RB1 analysis, but also illustrates the need for a deletion scanning approach. Finally, considering the benefits to retinoblastoma patients, RB1 testing should be widely implemented in routine healthcare because our study clearly illustrates its feasibility.

Child, Preschool↗

PubMed1992

A new intragenic polymorphism detected by the single-strand conformation polymorphism (SSCP) assay in the dystrophin gene.

We have employed the single strand conformation polymorphism (SSCP) technique to examine a group of patients with Duchenne or Becker muscular dystrophy who do not contain deletions detectable by multiplex PCR or Southern/cDNA, in an attempt to identify uncommon mutations within the dystrophin gene. In SSCP analysis, a mutated sequence can be detected as a change of mobility in a nondenaturing polyacrylamide gel. During the course of this investigation, we detected and characterized a new polymorphism at the 3' end of intron 16. The G-to-T base change creates a TaqI restriction site which allows for rapid typing of the polymorphism by restriction digestion and electrophoresis of PCR amplified products. Its localization inside the 5' region of the dystrophin gene and its high heterozygosity makes it a useful and easy tool for rapid carrier and prenatal diagnosis.

Base Sequence↗

PubMed2004

Genomic rearrangements in the CFTR gene: extensive allelic heterogeneity and diverse mutational mechanisms.

Cystic fibrosis (CF) is caused by mutations in the cystic fibrosis transmembrane conductance regulator gene (CFTR/ABCC7). Despite the extensive and enduring efforts of many CF researchers over the past 14 years, up to 30% of disease alleles still remain to be identified in some populations. It has long been suggested that gross genomic rearrangements could account for these unidentified alleles. To date, however, only a few large deletions have been found in the CFTR gene and only three have been fully characterized. Here, we report the first systematic screening of the 27 exons of the CFTR gene for large genomic rearrangements, by means of the quantitative multiplex PCR of short fluorescent fragments (QMPSF). A well-characterized cohort of 39 classical CF patients carrying at least one unidentified allele (after extensive and complete screening of the CFTR gene by both denaturing gradient gel electrophoresis and denaturing high-performance liquid chromatography) participated in this study. Using QMPSF, some 16% of the previously unidentified CF mutant alleles were identified and characterized, including five novel mutations (one large deletion and four indels). The breakpoints of these five mutations were precisely determined, enabling us to explore the underlying mechanisms of mutagenesis. Although non-homologous recombination may be invoked to explain all five complex lesions, each mutation appears to have arisen through a different mechanism. One of the indels was highly unusual in that it involved the insertion of a short 41 bp sequence with partial homology to a retrotranspositionally-competent LINE-1 element. The insertion of this ultra-short LINE-1 element (dubbed a "hyphen element") may constitute a novel type of mutation associated with human genetic disease.

Alleles↗

PubMed2005

Hereditary angioedema: the mutation spectrum of SERPING1/C1NH in a large Spanish cohort.

Hereditary angioedema (HAE) is a disease caused by defects in the C1 inhibitor gene (SERPING1/C1NH). We screened the entire C1NH gene for mutations in a large series of 87 Spanish families (77 with type I, and 10 with type II HAE) by SSCP, sequencing, Southern blotting, and quantitative multiplex PCR of short fluorescent fragments (QMPSF), and we characterized several defects at the mRNA level. We found large rearrangements in 13 families, and point mutations or microdeletions/insertions in 74 families. The 13 large rearrangements included nine exon deletions, of which at least eight were distinct, two were distinct exon duplications, and two were rearrangements whose precise nature could not be determined. We confirmed that exon 4 is particularly prone to rearrangements. Thirty-six mutations were unreported, and included 10 microdeletions/insertions, 10 missense, five nonsense, eight splicing, and three splicing or missense mutations. Moreover, we detected six novel uncharacterized sequence variants (USV). RT-PCR studies showed that in addition to several intronic splice site mutations tested, the exonic mutations c.882C>G and c.884T>G, located near the 3' end of exon 5, also produced exon skipping. This is the first evidence of SERPING1/C1NH mutations in coding regions that differ from the canonical splice sites that affect splicing, which suggests the presence of an exonic splicing enhancer (ESE) in exon 5.

Alternative Splicing↗

PubMed2005

Spectrum of gross deletions and insertions in the RB1 gene in patients with retinoblastoma and association with phenotypic expression.

Quantitative multiplex PCR and genomic real-time PCR were used to complete an RB1 mutation analysis in 57 of 433 and 72 of 262 patients with hereditary and isolated unilateral retinoblastoma, respectively. These patients were selected because in previous analyses, which focused mainly on the identification of point mutations, no RB1 mutation was found. We identified gross deletions and insertions in peripheral blood DNA from 26 of 57 patients (46%) with hereditary retinoblastoma, and in six of 72 patients (8.3%) with isolated unilateral disease. In addition, we identified 32 somatic mutations in tumor DNA from 31 of 72 patients (43%) with isolated unilateral retinoblastoma. Together with our previous results, we found that gross RB1 alterations were present in the peripheral blood DNA from 65 of 433 (15%) and 17 of 262 (6.5%) patients with bilateral or familial and isolated unilateral retinoblastoma, respectively. Including reported gross deletions, an analysis of the frequency of breakpoints per intron length shows higher densities in introns 13, 16, 23, and 24. Genotype-phenotype analyses showed that on the whole, carriers of gross deletions develop fewer retinoblastomas compared to patients who are heterozygous for other types of RB1 null mutations. Specifically, carriers of cytogenetic and submicroscopic whole gene deletions often have unilateral tumors only. By contrast, almost all patients with gross deletions with one breakpoint in RB1 have bilateral retinoblastoma.

DNA Mutational Analysis↗

PubMed2006

Different genetic pathways in the development of periocular sebaceous gland carcinomas in presumptive Muir-Torre syndrome patients.

Periocular sebaceous gland carcinomas (SGCs) occur in the eyelids either sporadically or as a phenotypic feature of Muir-Torre syndrome (MTS). In knockout mice mismatch-repair (MMR) defects or inactivation of the fragile histidine triad (FHIT) gene are associated with MTS-like signs, including SGC. To dissect the genetic alterations associated with microsatellite instability (MSI) and inactivation of the FHIT gene, we studied nine periocular SGC specimens from MTS patients. Immunohistochemistry was performed for FHIT, MSH2, MLH1, and MSH6. We assessed MSI as well as loss of heterozygosity (LOH) at the FHIT locus with polymorphic markers and genomic multiplex PCR. Epigenetic silencing was detected by methylation-specific PCR (MSP) and combined bisulfite restriction analysis (COBRA). Our analyses identified two SGCs with FHIT positivity and high-grade MSI, and seven cases with loss of FHIT and microsatellite stability (MSS). MSI correlated with loss of MSH2 and MLH1 immunostaining. Loss-of-function mechanisms affecting the FHIT gene were identified as intragenic deletions eliminating the coding exons 5 and 6 on one hand, and complete biallelic methylation of the FHIT transcription regulatory region on the other hand. Germinal FHIT mutations as a predisposing factor for MTS were excluded in two index patients with cancer in three generations, including an FHIT-negative SGC. Our data suggest that either somatic inactivation of the FHIT gene associated with MSS or inactivation of the MMR system resulting in MSI contribute to the development of periocular SGCs in presumptive MTS.

Acid Anhydride Hydrolases↗

PubMed2003

Germline mutations in the BRCA1 and BRCA2 genes in Turkish breast/ovarian cancer patients.

In this study we genotyped Turkish breast/ovarian cancer patients for BRCA1/BRCA2 mutations: protein truncation test (PTT) for exon 11 BRCA1 of and, multiplex PCR and denaturing gradient gel electrophoresis (DGGE) for BRCA2, complemented by DNA sequencing. In addition, a modified restriction assay was used for analysis of the predominant Jewish mutations: 185delAG, 5382InsC, Tyr978X (BRCA1) and 6174delT (BRCA2). Eighty three breast/ovarian cancer patients were screened: twenty three had a positive family history of breast/ovarian cancer, ten were males with breast cancer at any age, in eighteen the disease was diagnosed under 40 years of age, one patient had ovarian cancer in addition to breast cancer and one patient had ovarian cancer. All the rest (n=30) were considered sporadic breast cancer cases. Overall, 3 pathogenic mutations (3/53-5.7%) were detected, all in high risk individuals (3/23-13%): a novel (2990insA) and a previously described mutation (R1203X) in BRCA1, and a novel mutation (9255delT) in BRCA2. In addition, three missense mutations [two novel (T42S, N2742S) and a previously published one (S384F)] and two neutral polymorphisms (P9P, P2532P) were detected in BRCA2. Notably none of the male breast cancer patients harbored any mutation, and none of the tested individuals carried any of the Jewish mutations. Our findings suggest that there are no predominant mutations within exon 11 of the BRCA1 and in BRCA2 gene in Turkish high risk families.

Adult↗

PubMed2003

The 342-kb deletion in GJB6 is not present in patients with non-syndromic hearing loss from Austria.

Recently, a 342-kb deletion involving GJB6 was associated with autosomal-recessive non-syndromic hearing loss (NSHL) and in combination with a GJB2 mutation with digenic NSHL. This deletion was the second most common mutation causing prelingual NSHL in Spain, and was frequently observed in patients from France and Israel. We screened 393 patients with NSHL being negative or heterozygous for GJB2 mutations for this GJB6 deletion using a multiplex PCR. Most patients were of Austrian (84.2%), and the other patients were of Turkish, Serbian, and Bosnian origin. None of these patients was carrying the deletion in GJB6 indicating that the occurrence of this deletion is restricted to certain populations.

Austria↗