Evaluation of a candidate breast cancer associated SNP in ERCC4 as a risk modifier in BRCA1 and BRCA2 mutation carriers. Results from the Consortium of Investigators of Modifiers of BRCA1/BRCA2 (CIMBA).

BACKGROUND: In this study we aimed to evaluate the role of a SNP in intron 1 of the ERCC4 gene (rs744154), previously reported to be associated with a reduced risk of breast cancer in the general population, as a breast cancer risk modifier in BRCA1 and BRCA2 mutation carriers. METHODS: We have genotyped rs744154 in 9408 BRCA1 and 5632 BRCA2 mutation carriers from the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA) and assessed its association with breast cancer risk using a retrospective weighted cohort approach. RESULTS: We found no evidence of association with breast cancer risk for BRCA1 (per-allele HR: 0.98, 95% CI: 0.93-1.04, P = 0.5) or BRCA2 (per-allele HR: 0.97, 95% CI: 0.89-1.06, P = 0.5) mutation carriers. CONCLUSION: This SNP is not a significant modifier of breast cancer risk for mutation carriers, though weak associations cannot be ruled out.

Strategy in clinical practice for classification of unselected colorectal tumours based on mismatch repair deficiency.

OBJECTIVE: Deficiency of DNA mismatch repair (MMR) causes microsatellite instability (MSI) in a subset of colorectal cancers. Patients with these tumours have a better prognosis and may have an altered response to chemotherapy. Some of the tumours are caused by hereditary mutations (hereditary nonpolyposis colon cancer or Lynch syndrome), but most are epigenetic changes of sporadic origin. The aim of this study was to define a robust and inexpensive strategy for such classification in clinical practice. METHOD: Tumours and blood samples from 262 successive patients with colorectal adenocarcinomas were collected. Expression of the MMR proteins MLH1, MSH2, and MSH6 by immunohistochemistry (IHC) was compared with MSI DNA analysis. Methylation analysis of MLH1 and mutation analysis for BRAF V600E were compared in samples with MSI and/or lack of MLH1 expression to determine if the tumour was likely to be sporadic. RESULTS: Thirty-nine (14.9%) of the tumours showed MMR deficiency by IHC or by microsatellite analysis. Sporadic inactivation by methylation of MLH1 promoter was found in 35 patients whereby the BRAF activating V600E mutation, indicating sporadic origin, was found in 32 tumours. On the basis of molecular characteristics we found 223 patients with intact MMR, 35 patients with sporadic MMR deficiency, and four patients who were likely to have hereditary MMR deficiency. CONCLUSION: To obtain the maximal benefit for patients and clinicians, MMR testing should be supplemented with MLH1 methylation or BRAF mutation analysis to distinguish sporadic patients from likely hereditary ones. MMR deficient patients with sporadic disease can be reassured of the better prognosis and the likely hereditary cases should receive genetic counselling.

Annual surveillance by CA125 and transvaginal ultrasound for ovarian cancer in both high-risk and population risk women is ineffective.

OBJECTIVE: To assess the efficacy of annual CA125 and transvaginal ultrasound (TVU) scan as surveillance for ovarian cancer. DESIGN: Retrospective audit. SETTING: NHS Trust. POPULATION: Three hundred and forty-one asymptomatic women enrolled for ovarian cancer screening: 179 were in a high-risk group (>10% lifetime risk of developing ovarian cancer), 77 in a moderate risk group (4-10% lifetime risk of developing ovarian cancer) and 71 in a near population risk group (<4% lifetime risk). METHODS: Retrospective audit of case records, laboratory CA125 results, radiology reports, histology records and local cancer registry data. MAIN OUTCOME MEASURES: Ovarian cancers occurring in study population. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of TVU, and CA125 as a screening tool for ovarian cancer. RESULTS: Four ovarian cancers and one endometrial cancer occurred. One ovarian cancer was detected at surveillance, three occurred in women who presented symptomatically between screenings. Thirty women underwent exploratory surgery because of abnormal findings at surveillance. Two women had cancer (PPV = 6.7%); one had ovarian cancer and the other endometrial cancer. Twenty-eight women (93.3%) had no malignancy. Sensitivity, specificity, PPV and NPV for TVU in the whole cohort were 33.3, 85.8, 0.6 and 99.8%, respectively. For high-risk individuals, the figures for TVU were 33.3, 84.5, 1.1 and 99.6, respectively. Combining both modalities for the whole cohort, the sensitivity, specificity, PPV and NPV were 66.7, 82.9, 1.5 and 99.8% and 50.0, 82.8, 1.3 and 99.7%, respectively, for the high-risk group alone. CONCLUSIONS: Ovarian screening by annual TVU and CA125 is inefficient at detecting early-stage ovarian cancers.

Nuclei size in relation to nuclear status and aneuploidy rate for 13 chromosomes in donated four cells embryos.

PURPOSE: The aim was to elucidate if the nuclear size and number are indicative of aberrant chromosome content in human blastomeres and embryos. METHODS: The number of nuclei and the nucleus and blastomere size were measured by a computer controlled system for multilevel analysis. Then the nuclei were enumerated for 13 chromosomes by a combination of PNA and DNA probes. RESULTS: In the mononucleated embryos there was no difference in the mean size of chromosomally normal and abnormal nuclei but a significant difference in the mean nuclei size of nuclei that had gained chromosomes compared to nuclei that had lost chromosomes. The nuclei from multinucleated blastomeres had a significant smaller mean size and the frequency of chromosomally aberrant blastomeres was significantly higher. CONCLUSION: The mean nuclear size is not a marker for the chromosome content in mononucleated embryos. However, it seems that the nuclei size can be related to multinucleation and maybe to the chromosome content.

Evaluation of two different models to predict BRCA1 and BRCA2 mutations in a cohort of Danish hereditary breast and/or ovarian cancer families.

To meet the increasing demand for BRCA1 and BRCA2 mutation analysis, a robust system for selecting families who have a higher chance of a mutation has become important. Several models have been developed to help predict which samples are more likely to be mutation positive than others. We have undertaken a complete BRCA1 and BRCA2 mutation analysis in 267 Danish families with high-risk family history. We found deleterious mutations in 28% (76) of the families, 68% (52) of those in BRCA1 and 32% (24) in BRCA2. We compared our results with two popular manual models developed to estimate the chance of a positive result. One is the recently published Manchester model and the other is the Frank 2 model updated by Myriad Genetic Laboratories, Inc. Neither of the models would have suggested screening all mutation-positive samples. The Manchester model would have suggested screening 124 of the families in the cohort, thereby detecting 54 of 76 mutations (sensitivity 71%; specificity 63%), whereas the Frank 2/Myriad model would have found 60 of 76 mutations by screening 169 samples if a 10% likelihood was adapted (sensitivity 79%; specificity 43%). The updated Manchester model suggested screening 172 families whereby 64 mutations would have been detected (sensitivity 84%; specificity 44%). We conclude that although both models would have reduced the number of samples screened significantly, up to 28% of the mutations would not have been found by applying these models to this Danish cohort of families. This raises the question whether models designed for specific populations can be used in a wider setting.

'Indirect' BRCA1/2 testing: a useful approach in hereditary breast and ovarian cancer families without a living affected relative.

We report an approach for BRCA1/2 testing whereby genetic testing can be offered to families at high risk of hereditary breast and ovarian cancer but where no DNA from affected relatives is available. By testing two or more unaffected relatives at 50% risk of being heterozygous for a potential BRCA1/2 mutation, there is a chance of up to 99% of finding a mutation that would have been detectable in an affected individual from the same family. The overall likelihood of identifying a mutation is dependent on the family history, and therefore 'indirect' testing would be most applicable for families with a very high risk of carrying a BRCA1/2 mutation. Using this approach also requires balancing issues of testing resource limitations, family dynamics and adequate preparation of unaffected persons for a positive test, with the advantages of targeting screening and prophylactic surgery.

Sequential FISH analysis using competitive displacement of labelled peptide nucleic acid probes for eight chromosomes in human blastomeres.

BACKGROUND: The aim was to introduce a new strategy based on peptide nucleic acid (PNA) probes and competitive displacement for using fluorescence in-situ hybridization (FISH) analysis on human blastomeres. METHODS: Sequential FISH analysis with PNA probes and competitive displacement was performed using three different probe sets. The first set consisted of labelled probe only. The second and third sets included labelled as well as unlabelled probe, corresponding to the labelled probes in the previous cycles. The probes for enumeration were for chromosome 1, 13, 16, 17, 18, 21, X and Y. RESULTS: The performance of PNA probes was similar to the established DNA probes. The strategy of competitive displacement resulted in a destabilization of already bound probe before the next FISH cycle at only 50 degrees C, which allowed for up to five sequential FISH cycles without loss of signal. CONCLUSIONS: PNA probes are a good alternative to DNA probes in the present set-up, since the low temperature required both for binding and destabilization of PNA probes minimizes the loss of signal, and several FISH cycles can therefore be carried out before FISH errors occur.

Quantitative evaluation of fluorescence in situ hybridization (FISH) signals in uncultured coelomic cells.

Uncultured coelomic cells were hybridized with alpha satellite DNA probes representing chromosomes X, Y, 18, and 13/21 in order to evaluate the distribution of hybridization signals obtained by fluorescence in situ-hybridization (FISH) analysis of this cell type. Cells from 26 samples were hybridized with the X probe and the Y probe was hybridized with cells from 25 of the samples. Cells from 16 and 11 samples were hybridized with an 18 alpha satellite DNA probe and 13/21 alpha satellite probe, respectively. The evaluation demonstrated that FISH with X, Y, 18, and 13/21 alpha satellite DNA probes on uncultured coelomic cells is a reliable technique since the distribution of hybridization signals is comparable to that seen in uncultured amniotic fluid cells.

Early prenatal diagnosis: standard cytogenetic analysis of coelomic cells obtained by coelocentesis.

Coelomic fluid samples (n = 30) were obtained from normal pregnancies between 6.0 and 10.0 weeks and attempts to culture the coelomic cells were made. With one culture system, nine of ten samples were cultured and successful cytogenetic analysis was performed. There have been no previous reports of traditional cytogenetic analysis of coelomic cells and this might be the breakthrough for coelocentesis as a future method for early prenatal diagnosis.

Genetic analysis of males from intracytoplasmic sperm injection couples.

A total of 392 men referred for intracytoplasmic sperm injection (ICSI) participated in genetic analysis. The control group consisted of 100 normal fertile males. Chromosome and DNA analyses were performed to investigate the frequency of Y-chromosome microdeletions and CFTR mutations (the controls underwent DNA analysis only). An abnormal karyotype was found in 4.6% of all males, but the frequency among men with azoospermia was higher, at 11.7%. Y-chromosome microdeletions were found only among men with azoospermia (6.5%) and men with extreme oligospermia (2%). Compound heterozygosity for CFTR mutations was found in men with azoospermia (3.9%) and congenital bilateral absence of vas deferens (CBAVD) only. We conclude that all couples referred for ICSI should be offered chromosome analysis. DNA analysis for Y-chromosome microdeletions should be reserved for men with azoospermia or extreme oligospermia (<1 x 106 spermatozoa). Analysis for CFTR mutations should be limited to those with obstructive azoospermia or those with a family history of cystic fibrosis.