BRCA1 mutation update and analysis

The discovery of the BRCA1 gene involved in the development of human hereditary breast cancer led to extensive international efforts to identify the mutations leading to the disease. The new listing covers 127 mutations published in the indicated papers before 30 April 1996; 55% of the mutations are localized in exon 11, followed by exons 2 (5.5%), 5 and 16 (4.7% each).     

A high proportion of novel mutations in BRCA1 with strong founder effects among Dutch and Belgian hereditary breast and ovarian cancer families

We have identified 79 mutations in BRCA1 in a set of 643 Dutch and 23 Belgian hereditary breast and ovarian cancer families collected either for research or for clinical diagnostic purposes. Twenty-eight distinct mutations have been observed, 18 of them not previously reported and 12 of them occurring more than once. Most conspicuously, a 2804delAA mutation has been found 19 times and has never been reported outside the Netherlands. A common haplotype spanning > or = 375 kb could be identified for each of the nine examined recurrent mutations, indicating the presence of multiple BRCA1 founder mutations in the Dutch population. The 2804delAA mutation has been estimated to have originated approximately 32 generations ago. No specific breast or ovarian cancer phenotype could be assigned to any of the common mutations, and the ovarian cancer incidence among 18 families with the 2804delAA mutation was heterogeneous.     

Haplotype and phenotype analysis of six recurrent BRCA1 mutations in 61 families: results of an international study

Central to the Mu transpositional recombination are the two chemical steps; donor DNA cleavage and strand transfer. These reactions occur within the Mu transpososome that contains two Mu DNA end segments bound to a tetramer of MuA, the transposase. To investigate which MuA monomer catalyzes which chemical reaction, we made transpososomes containing wild-type and active site mutant MuA. By pre-loading the MuA variants onto Mu end DNA fragments of different length prior to transpososome assembly, we could track the catalysis by MuA bound to each Mu end segment. The donor DNA end that underwent the chemical reaction was identified. Both the donor DNA cleavage and strand transfer were catalyzed in trans by the MuA monomers bound to the partner Mu end. This arrangement explains why the transpososome assembly is a prerequisite for the chemical steps.     

Randomized trial of a decision aid for BRCA1/BRCA2 mutation carriers: Impact on measures of decision making and satisfaction.

Objective: Genetic testing is increasingly part of routine clinical care for women with a family history of breast cancer. Given their substantially elevated risk for breast cancer, BRCA1/BRCA2 mutation carriers must make the difficult decision whether or not to opt for risk reducing mastectomy. To help BRCA1/2 carriers make this decision, the authors developed a computer-based interactive decision aid that was tested against usual care in a randomized controlled trial. Design: After the completion of genetic counseling, 214 female (aged 21-75) BRCA1/BRCA2 mutation carriers were randomized to Usual Care (UC; N = 114) or Usual Care plus Decision Aid (DA; N = 100) arms. UC participants received no additional intervention. DA participants were sent the CD-ROM DA to view at home. Main Outcome Measures: The authors measured final management decision, decisional conflict, decisional satisfaction, and receipt of risk reducing mastectomy at 1-, 6-, and 12-months postrandomization. Results: Longitudinal analyses revealed that the DA was effective among carriers who were initially undecided about how to manage their breast cancer risk. Within this group, the DA led to an increased likelihood of reaching a management decision (OR = 3.09, 95% CI = 1.62, 5.90; p     

Sequence analysis of BRCA1 and BRCA2: correlation of mutations with family history and ovarian cancer risk

PURPOSE: Previous studies of mutations in BRCA1 or BRCA2 have used detection methods that may underestimate the actual frequency of mutations and have analyzed women using heterogeneous criteria for risk of hereditary cancer. PATIENTS AND METHODS: A total of 238 women with breast cancer before age 50 or ovarian cancer at any age and at least one first- or second-degree relative with either diagnosis underwent sequence analysis of BRCA1 followed by analysis of BRCA2 (except for 27 women who declined analysis of BRCA2 after a deleterious mutation was discovered in BRCA1). Results were correlated with personal and family history of malignancy. RESULTS: Deleterious mutations were identified in 94 (39%) women, including 59 of 117 (50%) from families with ovarian cancer and 35 of 121 (29%) from families without ovarian cancer. Mutations were identified in 14 of 70 (20%) women with just one other relative who developed breast cancer before age 50. In women with breast cancer, mutations in BRCA1 and BRCA2 were associated with a 10-fold increased risk of subsequent ovarian carcinoma (P = .005). CONCLUSION: Because mutations in BRCA1 and BRCA2 in women with breast cancer are associated with an increased risk of ovarian cancer, analysis of these genes should be considered for women diagnosed with breast cancer who have a high probability of carrying a mutation according to the statistical model developed with these data.     

Birthdate and cell marker analysis of scrambler: a novel mutation affecting cortical development with a reeler-like phenotype

The reeler mutation in mice produces an especially well characterized disorder, with systematically abnormal migration of cerebral cortical neurons. The reeler gene encodes a large protein, termed Reelin, that in the cortex is synthesized and secreted exclusively in the Cajal-Retzius neurons of the cortical marginal zone (D'Arcangelo et al., 1995). In reeler mutant mice, loss of Reelin protein is associated with a systematic loss of the normal, "inside-out" sequence of neurogenesis in the cortex: neurons are formed in the normal sequence but become localized in the cortex in a somewhat inverted, although relatively disorganized "outside-in" pattern. Here we show that the scrambler mutant mouse exhibits a loss of lamination in the cortex and hippocampus that is indistinguishable from that seen in the reeler mouse. We use BrdU birthdating studies to show that scrambler cortex shows a somewhat inverted "outside-in" sequence of birthdates for cortical neurons that is similar to that previously described in reeler cortex. Finally, we perform staining with the CR-50 monoclonal antibody (Ogawa et al., 1995), which recognizes the Reelin protein (D'Arcangelo et al., 1997). We show that Reelin immunoreactivity is present in the scrambler cortex in a normal pattern, suggesting that Reelin is synthesized and released normally. Our data suggest that scrambler is a mutation in the same gene pathway as the reeler gene (Relnrl) and is most likely downstream of Relnrl.     

Correlation between P450 CYP1A1 inducibility, MspI genotype and lung cancer incidence

The aim of this study was to verify a possible correlation between CYP1A1 induction, MspI genotype and lung cancer incidence. A case-control study was performed on 48 lung cancer patients and 81 healthy subjects to test the existence of a correlation, within a European population. The hyperinducible group exhibited a significantly higher risk of lung cancer (odds ratio = 3.41; P = 0.036), especially for adenocarcinoma (odds ratio = 5.29; P = 0.033). In contrast with the situation observed in Asian populations, the frequency of the M2 allele did not differ significantly in the total lung cancer population (7.82%) and the group of healthy subjects (10.71%). The median inducibility value was slightly higher among cancer patients with one or two M2 alleles than among patients homozygous for the wild-type allele (P = 0.09). However, the percentage of individuals possessing at least one mutated allele was not significantly higher among hyperinducible patients (37.5%) than among non-hyperinducible patients (16.0%). No significant correlation could be found between M2 allele and lung cancer or between M2 allele and CYP1A1 inducibility; the only positive correlation found was between CYP1A1 hyperinducibility and lung cancer incidence. Our observations do not support the view that the presence of the M2 allele at the MspI site of the CYP1A1 gene constitutes a significant lung cancer risk in Caucasians.     

SCA1, SCA2, MJD/SCA3 (CAG)n mutation detection and analysis in patients with hereditary spinocerebellar ataxia from Chinese families

OBJECTIVE: To assess the frequency of the SCA1, SCA2, MJD/SCA3 CAG trinucleotide repeat expansions ((CAG)n) among individuals diagnosed with hereditary spinocerebellar ataxia (SCA) from Chinese families. METHOD: The SCA1, SCA2, MJD/SCA3 (CAG)n mutation were detected with the polymerose chain reaction (PCR), denaturing polyacrylamide gel and silver staining technique in 79 patients with autosomal dominant SCA from 50 Chinese families. RESULTS: Among 50 kindreds, 2% (1/50) had the SCA1, (CAG)n, 6% (3/50) had the SCA2, (CAG)n, whereas 48% (24/50) were positive for the MJD/SCA3 (CAG)n. Thus, together SCA1, SCA2, and MJD/SCA3 represent 56% (28/50) of the autosomal dominant ataxias in our group. In two SCA1 patients the CAG repeat was expanded to 53-62 repeats, whereas in normal ivdividuals was 12-36 repeats. In seven SCA2 patients the CAG repeat was expanded to 43-47 repeats, whereas in normal ivdividuals was 22-30 repeats. In forty-two MJD/SCA3 patients the CAG repeat was expanded to 63-78 repeats, whereas in normal ivdividuals was 15-38 repeats. The SCA1, SCA2, MJD/SCA3 (CAG)n mutation were excluded in the other 28 SCA patients from 22 families. CONCLUSION: The frequency of MJD/SCA3 is substantially higher than that of SCA1 and SCA2 in the autosomal dominant SCA from Chinese families. Chinese patients with MJD/SCA3 are non-Portuguese patients with MJD/SCA3. Clinical expressions of the various SCAs overlap one another, making a diagnostic classification based on phenotype inaccurate in many instances. It is important for SCA clinical study to make a SCA gene diagnosis and genomic classification.     

Germ-line mutation analysis in patients with multiple endocrine neoplasia type 1 and related disorders

Centrosomes and microtubules play crucial roles during cell division and differentiation. Spermatogenesis is a useful system for studying centrosomal function since it involves both mitosis and meiosis, and also transformation of the centriole into the sperm basal body. Centrosomin is a protein localized to the mitotic centrosomes in Drosophila melanogaster. We have found a novel isoform of centrosomin expressed during spermatogenesis. Additionally, an anticentrosomin antibody labels both the mitotic and meiotic centrosomes as well as the basal body. Mutational analysis shows that centrosomin is required for spindle organization during meiosis and for organization of the sperm axoneme. These results suggest that centrosomin is a necessary component of the meiotic centrosomes and the spermatid basal body.     

A male child with the rumpshaker mutation, X-linked spastic paraplegia/Pelizaeus-Merzbacher disease and lysinuria

Of 52 antibiotic-resistant Bordetella bronchiseptica isolates from cats, ten carried plasmids. Only two of these plasmids, pLV1400 and pLV1401, were self-transmissible to Escherichia coli K12; both plasmids encoded resistance to ampicillin, tetracycline, sulphonamides, streptomycin and mercuric chloride, and were of incompatibility group P (IncP). Transferable tetracycline resistance has not been reported in B. bronchiseptica previously. The plasmids were identical in size (c.51 kb), restriction endonuclease digestion pattern and gene sequences (trfA and korA) within the IncP replicon. The trfA and korA sequences differed from those of the archetypal IncP plasmids RP4 and R751. Although the two B. bronchiseptica isolates were from epidemiologically and geographically separated cats, pulsed-field gel electrophoresis of their XbaI- or DraI-digested chromosomal DNA indicated that they were genotypically identical. The plasmid-encoded ampicillin resistance was mediated by a penicillinase of molecular weight 49,000, and pI 8.45 which was inhibited by clavulanate (IC50 = 0.1 mg/L) and tazobactam (IC50 = 0.42 mg/L) but not by parachloromercuribenzoate or EDTA. The high-level tetracycline resistance was mediated by a class C efflux mechanism that has not been described previously in this genus. The presence of transferable multi-drug resistance on a promiscuous plasmid may limit options for therapy of respiratory tract infection in companion and farm animals.     

A new mutation, 3905insT, accounts for 4.8% of 1173 CF chromosomes in Switzerland and causes a severe phenotype

The objective of this study was to determine the predictive value of the number of follicles seen by transvaginal ultrasound before gonadotrophin stimulation on the ovarian responsiveness of 166 infertile women undergoing in-vitro fertilization (IVF) treatment. The main variables were patient age, ovarian volume and number of ovarian follicles measuring 2-5 mm on transvaginal ultrasound before gonadotrophin stimulation. Based on the sum of ovarian follicles in both ovaries the patients were divided into three groups of inactive (<5 follicles), normal (5-15 follicles) or polycystic (PCO)-like ovaries (>15 follicles). The main outcome measure was the number of recovered oocytes. The number of follicles was correlated more strongly with the number of recovered oocytes (r2 = 0.131; P = 0.0001) than age alone (r2 = -0.053; P = 0.005). Fewer oocytes were recovered from patients with inactive ovaries (5.4 +/- 2.5; P = 0.006) than with normal (7.5 +/- 4.5) or PCO-like ovaries (10.5 +/- 5.1). Ovarian volume was correlated with the number of follicles before stimulation (P = 0.0001), but not with the number of oocytes. The number of small follicles present before ovarian stimulation was a better predictor of the outcome than ovarian volume or age alone. Patients can be identified with inactive ovaries which will have a poor response to IVF treatment, a key factor for counselling couples and optimizing resources.     

A diabetogenic gene, ODB2, identified on chromosome 14 of the OLETF rat and its synergistic action with ODB1

Genetic analysis of diabetogenic genes involved in developing spontaneous diabetes of NIDDM type in the OLETF rat was performed in (OLETF female X B N male)F2 and (OLETF female X BN male)F1 female X OLETF male backcross male offspring. In the F2 and/or backcross offspring, a high frequency of diabetes was found to be associated with a coat color gene, H (hooded). Since it is know that H gene is located on chromosome 14. an attempt was made to examine the linkage association of the gene responsible for elevating plasma glucose with various microsatellite markers of chromosome 14 in male F2 and/or backcross offspring. The results show that a high linkage exists with a microsatellite marker, D14Mit4 (LOD > 2). The gene was designated Odb2. It was also found that both genes, Odb1 which was previously found on chromosome X, and homozygous Odh2 are required to cause elevated plasma glucose in OGTT.     

A mutation in the AMPA-type glutamate receptor, glr-1, blocks olfactory associative and nonassociative learning in Caenorhabditis elegans.

The α-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA)-type ionotropic glutamate receptor mediates fast excitatory neurotransmission in the vertebrate brain and is important for synaptic plasticity and the initial induction of long-term potentiation (LTP). This study found that the putative Caenorhabditis elegans AMPA receptor gene, glr-1, plays a significant role in experience-dependent behavior in C. elegans. glr-1 mutants are deficient in an olfactory associative learning task, in which diacetyl (DA) is paired with acetic acid solution. glr-1 mutant nematodes are also impaired in nonassociative learning (habituation) with the same DA stimulus. The C. elegans learning mutants, lrn-1 and lrn-2, are impaired in chemosensory associative learning yet have no deficits in habituation. The results suggest that although associative and nonassociative learning can be genetically dissociated ( lrn-1 and lrn-2), they also share some common molecular processes, including glr-1 -mediated neurotransmission. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Microsatellite deletion mapping on chromosome 10q and mutation analysis of MMAC1, FAS, and MXI1 in human glioblastoma multiforme

The aim of this study was to determine the relationship between calcium ionophore A23187-induced acrosome reaction (AR) and sperm fertilizing ability. Semen samples remaining after preparation for standard IVF were studied in 109 patients who had sperm concentrations > or =20 x 10(6)/ml. Ionophore-induced AR was performed on motile spermatozoa selected by centrifugation on a Percoll gradient. Semen analysis was performed using standard methods. Patients with higher (>50%, n = 76) fertilization rates had significantly higher ionophore-induced AR than patients with lower (<50%, n = 33) fertilization rates (49 +/- 14 versus 38 +/- 21%, P < 0.05). When the data from all patients were analysed by logistic regression, only the percentage sperm motility in insemination medium and ionophore-induced AR were significantly related to fertilization rates. Similar results were also obtained when the data from a subgroup of patients with poor (<15% normal) sperm morphology were analysed. However, when patients with normal sperm morphology > or =15% were analysed separately, only sperm count and the percentage of spermatozoa with progressive motility in semen were significantly related to fertilization rates. In conclusion, ionophore-induced AR was significantly related to fertilization rates in vitro mainly in patients with teratozoospermic semen. Tests for ionophore-induced AR may provide additional information about sperm fertilizing ability but may not indicate specific defects of the physiological AR.     

迭代算法A与Q/Hampel方法在能力验证结果分析中的比较

能力验证计划实施中,要按照科学的统计方法分析能力验证参加者的测定结果,并给出公平合理的评价。通常优先采用对离群值相对不敏感的稳健统计方法进行能力验证结果分析。通过实际检测数据计算实例,对比了迭代算法A与Q/Hampel两种稳健统计方法的计算结果。研究表明:两种稳健统计方法计算的稳健平均值基本相同,计算的稳健标准差存在区别,但对各实验室检测能力评价一致。能力验证结果中存在局部众数时,迭代算法A和Q/Hampel方法计算所得稳健平均值比值为1.03,而两者稳健标准差比值达到了2.32,Q/Hampel方法比迭代算法A表现出更好的稳健可靠性。