Search

Estimating the age of founder mutations may contribute to improve our knowledge of population genetics and evolutionary history of diseases. Previous haplotype analysis suggested that the BRCA1*1499insA mutation was a founder allele, probably originated in Tuscany (Italy). Here, we collected additional pedigrees carrying this mutation, and applied a phylogenetic method for estimating mutation age. A chromosome segment of about 25 cM, including 37 short tandem repeats (STRs) on both sides of the BRCA1 gene (DeCode map), was typed in 50 subjects (28 mutation carriers) from 14 unrelated families. The time to the most recent common ancestor (MRCA) of the mutation carriers was estimated by the length of the shared haplotype between all possible pairs of individuals. A function relating the length of the shared haplotype to the time to the MRCA was obtained by a computer simulation. This approach gives results comparable with those of other existing mutation-dating methods, but does not depend explicitly on population-specific parameters such as allele frequencies, provides narrower confidence intervals (CI), and allows one to build an extended genealogical tree of all mutation carriers. The 1499insA mutation shared by the investigated subjects was estimated to be present in an individual living about 30 generations ago (95% CL 22-56), or 750 years (95% CL 550-1,400).

Alterations in BRCA1 and BRCA2 genes account for a large proportion of hereditary breast and ovarian cancers. Mutations and variants of unknown pathological significance have been identified in both genes; however, most of them have been studied only at the genomic level, and their effect on mRNA expression remains unknown. We identified two BRCA1 and six BRCA2 splice site variants, and one BRCA2 alteration at exon 14. Our aim was to ascertain the effect on RNA processing of the variants still unclassified. We found that BRCA1 c.IVS11 + 1G>A, BRCA2 c.7252_7272delinsTG, BRCA2 c.IVS2 + 1G>A, BRCA2 c.IVS13-2A>G, BRCA2 c.IVS21 + 4A>G, and BRCA2 c.9345G>A lead to aberrant transcripts in lymphocytes. Five of these six splice site variants caused a complete inactivation of the mutant allele because they produced frameshift similar to previously described deleterious exonic variants. Therefore, we consider them to be true deleterious mutations, possibly associated with an increased lifetime risk of breast or ovarian cancer. BRCA1 c.IVS17 + 6C>G, BRCA2 c.IVS12-9del4, and BRCA2 IVS1-9del3 represent rare variants, not disrupting normal mRNA processing. The last two BRCA2 genetic variants had not been reported in the Breast Cancer Information Core BIC database.

Introduction. Breast papillary lesions represent a heterogeneous group of tumors ranging from benign to malignant, including several intermediate forms. Malignant papillary tumors are rare and their molecular characterization is still limited. A few studies pointed to the presence of specific genetic alterations that could be relevant both for diagnostic purposes and to elucidate tumour development and progression. In order to look into the issue, we compared LOH relative frequencies of four microsatellite markers located on chromosome 16 in a set of morphologically different papillary breast lesions. LOH at TP53 locus was also analyzed throughout lesions. Materials and methods. Fifteen cases were analyzed. Sections including a malignant papillary lesion, a benign lesion (when available), and normal breast tissue were selected. Fifteen malignant and twelve benign areas were microdissected using the Leica laser microdissection system (AS LMD). After DNA extraction samples were tested for the following markers: TP53, D16S423, D16S310, DS163210 and D16S476, and analyzed on ABI PRISM 3100 (Applied Biosystems, Foster city CA). Results. Fourteen malignant lesions and twelve paired benign areas appeared to be informative for at least one of the four markers on chromosome 16. In particular, LOH at loci 16p13 and 16q21 was detected in both benign and malignant lesions, whereas LOH at locus 16q23 was limited to malignant lesions. Nine malignant and seven benign lesions were informative for LOH at TP53 locus, that was found to be significantly associated (p=0.01) with the malignant phenotype. Conclusions. Our data suggest an involvement of chromosome 16 mutations in the early steps of breast papillary tumorigenesis. TP53 deletion and possibly LOH at 16q23 appear to play a role as progression factors, being they significantly associated with malignant transformation of breast papilloma.

Mutations in BRCA1 and BRCA2 show different expressivity with respect to cancer risk, and allelic heterogeneity may be present in both genes. We collected 179 pedigrees with identified germline mutation (104 BRCA1 and 75 BRCA2), ascertained in six collaborating centers of the Italian Consortium for Hereditary Breast and Ovarian Cancer. Significant heterogeneity was detected for several variables, and a logistic regression model including age of diagnosis in the proband, presence of ovarian cancer in the family, presence of prostate or pancreatic cancer in the family, and presence of male breast cancer in the family proved to be effective in predicting the presence of a mutation in a gene rather than the other. Excess of familial aggregation of both breast and ovarian cancer was observed in both genes. Proportion of ovarian cancer was increased in the 5' portion of BRCA1, and presence of prostate or pancreatic cancer in a family was correlated with presence of ovarian cancer in BRCA2.

BACKGROUND: Epidermal growth factor (EGF) plays an important role in carcinogenesis. An adenine (A) to guanine (G) single nucleotide polymorphism at position 61 in the 5'-untranslated region (5'-UTR) of the EGF gene has been found to be associated with levels of EGF production and contribute to the risk of glioma. However, published data are contradictory. EGF +61G/A polymorphism may contribute to the risk of glioma in different ethnic group. Patients with glioma and GG genotype have been reported to have a risk of poorer outcome than patients with AA genotype. Purpose of this study is to investigate the potential role of this polymorphism in cancer progression and its role as predictive marker of outcome in glioma caucasian patients. METHODS: The significant SNP rs4444903, EGF 61A/G, was analyzed in glioma patients and was determined by means of Polymerase Chain Reaction and Direct Sequencing method from blood samples. Association of this genetic polymorphism with clinical and pathological data of patients was evaluated. RESULTS: We investigated EGF +61G/A polymorphism in 28 glioma patients. EGF +61G allele has been found in 68% of glioma patients (22% G/G genotype and 46% A/G genotype). In astrocytomas, EGF +61G allele represents a 83% frequency; in glioblastomas and in oligodendrogliomas, EGF +61G allele frequency represents respectively 73% and 54%. In WHO IV gliomas, the EGF +61G allele represents a 72% frequency, (27% G/G and 45% A/G ), in WHO III gliomas a 81% frequency (54% G/G and 27% A/G ) and in WHO II gliomas a 33% frequency (80% A/G ). Median PFS of glioblastoma patients was 9 months. 79% of glioblastoma patients with a relapsing disease showed the G/G and A/G genotype. No difference was detected in the others histotypes. CONCLUSIONS: Our data confirm previous studies which reported G allele as a risk factor for glioma in Caucasian. G/A and G/G genotypes seem to be more rappresentative in high grade gliomas . Despite limited number of patients, our study supports the predictive role of EGF 61 A/G polymorphism in GBM. Additional large studies are warranted to confirm the role of EGF polymorphism as indipendent prognostic factor in glioma.

nm23 gene expression is strictly related to the state of cell growth. The level of its expression parallels the fraction of thymidine-incorporating cells (S-phase cells) in neoplastic mammary tissues and in the synchronously cycling fraction of MCF10A cells. nm23.h1 reaches a peak of expression in the S-phase, and is present at very low level during the G0/G1 phase. Two strategies are used to demonstrate the direct involvement of the nm23.h1 gene in the process of cell proliferation. The first consists of transient inhibition of nm23.h1 expression by using anti-sense oligonucleotide treatment; weak inhibitory effect on cell proliferation is observed. The second strategy involves the stable inhibition of nm23.h1 expression by transfection of MCF10A cells with a plasmid vector expressing the human nm23.h1 anti-sense mRNA. The anti-sense-transfected cells show consistently slower proliferative activity than the control. Int. J. Cancer 73:297–302, 1997. © 1997 Wiley-Liss, Inc.

The NM23 gene has been proposed as a metastasis-suppressor gene, and its use has been suggested as prognostic factor. NM23 was identified in a system of murine melanoma cell lines, in which an inverse relationship was found between NM23 expression and metastatic ability. In a human malignant melanoma study NM23 expression was found to be significantly lower in metastases that developed less than 24 months after diagnosis of the primary tumours. The present paper studies the expression of the NM23.H1 gene in cell lines which derive from primary or metastatic human malignant melanomas in relation to staging, infiltration degree, lymphocytic infiltration, cell morphology, cell pigmentation, karyotype, and disease-free survival. The level of mRNA expression of the NM23 gene is significantly lower in cell lines that derive from more infiltrating primary melanomas than in cell lines obtained from less infiltrating tumours. Moreover, cell lines derived from tumours of patients with a disease-free survival of more than 24 months (24-58 months) express the NM23 gene at higher levels than cell lines obtained from melanomas of patients with a disease-free survival of less than 24 months (6-15 months).

BRCA1 has been characterized as one of the major breast cancer susceptibility genes. Although no BRCA1 mutations have been reported in sporadic breast cancer, altered levels of BRCA1 are found in non hereditary breast malignant lesions. Therefore, BRCA1 is potentially playing a key role in the genesis of breast cancer. In this study, we explored the effects of estradiol and two differentiating agents, the progestin ORG2058 and retinoic acid, on BRCA1 mRNA expression in human estrogen and progesterone receptor positive MCF-7 cells. Using RNAse protection assay, we have demonstrated that ORG2058 induces a major (50 times) stimulation of BRCA1 mRNA expression. The maximum induction effect was obtained at the pharmacological dose of 100 nM and after 48 h of treatment. While estradiol generated an expected increase of BRCA1 mRNA, retinoic acid did not produce any effects. Our results demonstrate for the first time that BRCA1 is specifically up-regulated by a progestin, a steroid known to induce the differentiation of epithelial mammary cells. The absence of retinoic acid effect suggests that a specific progesterone-dependent pathway, could control BRCA1 expression.

1. 1. We have measured protein kinase C (PKC) activity in cytosolic fractions of leech central nervous system. 2. 2. Phosphatidylserine and oleylacetylglycerol enhanced the activity of the enzyme in a dose-dependent manner even in the absence of calcium. 3. 3. Most of the substrates of the calcium-dependent protein kinase are substrates of the PKC. 4. 4. H-7 and polymyxin B inhibited both PKC and Ca 2+ -dependent protein kinase.

Two human NM23 genes have been identified: NM23.H1 and NM23.H2 coding for the A and B subunit of a nucleoside diphosphate kinase (NDPK), respectively. NM23.H1 gene has been proposed as a suppressor of metastatic ability in tumor cells, NM23.H2 is identical to the c-myc transcription factor, PuF. The NM23 coding sequence is strongly preserved through different species. Indirect evidence of various types has been accumulated and seems to support an implication of NM23 in cell proliferation. This report shows that the NM23 gene expression is strictly related to the growth state of the cells. Two different in vitro systems (human peripheral blood lymphocytes and human breast epithelial cell line MCF-10A) and one in vivo (human primary infiltrating ductal breast carcinomas) system have been investigated. The mRNA is present in PHA-stimulated peripheral blood lymphocytes, whereas it is nearly undetectable in their resting counterparts. The level of the NM23 gene expression parallels the fraction of cells incorporating thymidine (S-phase) in neoplastic mammary tissues. In synchronously cycling MCF-10A cells NM23.H1 mRNA reaehes a maximum abundance in the S-phase and is absent or only present at very low levels during G 0 /G 1 phase, whereas NM23.H2 is present in growth- arrested cells but is upregulated following serum growth stimulation

Germ-line mutations in the BRCA1 gene cause hereditary predisposition to breast and ovarian cancer. BRCA1 and BRCA2 mutations account for about 40% of high-risk families. Mutation-screening methods generally focus on genomic DNA and are usually PCR based; they enable the detection of sequence alterations such as point mutations and small deletions and insertions. However, they do not allow the detection of partial or entire exon(s) loss, because the presence of the homologous allele results in a positive PCR signal, giving rise to a false-negative result. Identification of unusual haplotypes in patient samples by an expectation maximisation algorithm has recently been suggested as a method for identifying hemizygous regions caused by large intragenic deletions. Using a similar approach, we identified a novel BRCA1 genomic rearrangement in a breast/ovarian cancer family negative at the first mutation screening; we detected a deletion encompassing exons 14–19, probably due to replication slippage between Alu sequences.

GADD45 is a DNA damage responsive gene, induced following BRCA1 expression. Mutations at GADD45 might substitute for p53 alterations in hereditary breast tumours characterized by wild-type p53. We analyzed GADD45 alterations in 59 (15 BRCA-associated) familial breast carcinomas. No mutations were found. LOH at GADD45 locus was identified in 19/59 tumours. GADD45 does not appear to be a frequent mutational target in hereditary breast cancer.

Genetic linkage studies have led to the identification of highly penetrant genes as the possible cause of inherited cancer risk in many cancer-prone families. Most women with a family history of breast/ ovarian cancer have tumors characterized by alterations in particular genes, mainly BRCA1 and BRCA2, but also CHK2, ATM, STK11 and others. This paper examines the BRCA1 and BRCA2 genes, focusing on the Italian pattern of mutations. The function of these two genes, classified as tumor suppressors, is linked with key metabolic mechanisms such as DNA damage repair, regulation of gene expression and cell cycle control. The pathological BRCA allelic variants may cause alteration of protein function, transcriptional activity and DNA repair; accumulation of the defects leads to widespread chromosome instability that may be directly responsible for cancer formation. In fact, mutations in BRCA1 and BRCA2, conferring a highly increased susceptibility to breast and ovarian cancer, do not lead to cancer by themselves. The current consensus is that these are ‘caretaker’ genes, which, when inactivated, allow other genetic defects to accumulate. The nature of these other molecular events may define the pathway through which BRCA1 and BRCA2 act. The BRCA mutation spectrum is complex, and the significance of most nucleotide alterations is difficult to understand. Moreover, the mutation pattern seems to be related to ethnicity. The Italian Consortium of Hereditary Breast and Ovarian Cancer has reviewed 1758 families; 23% have been found to be carriers of pathogenetic mutations in BRCA1 or BRCA2. Founder mutations have been described in geographically restricted areas of Italy; a regional founder effect has been demonstrated in Italy for the mutations BRCA1 5083del19 and BRCA2 8765delAG, and a probable new founder mutation has been characterized in Tuscany. The presence of founder mutations has practical implications for genetic testing.

Accurate estimates of breast and ovarian cancer penetrance in BRCA1/2 mutation carriers are crucial in genetic counseling. Estimation is difficult because of the low frequency of mutated alleles and the often-uncertain mechanisms of family ascertainment. We estimated the penetrances of breast and ovarian cancers in carriers of BRCA1/2 mutations by maximizing the retrospective likelihood of the genetic model, given the observed test results, in 568 Italian families screened for germline mutations. The software BRCAPRO was used as a probability calculation tool in a Markov Chain Monte Carlo approach. Breast cancer penetrances were 27% (95% CI 20-34%) at age 50 years and 39% (27-52%) at age 70 in BRCA1 carriers, and 26% (0.18-0.34%) at age 50 and 44% (29-58%) at age 70 in BRCA2 carriers, and ovarian cancer penetrances were 14% (7-22%) at age 50 and 43% (21-66%) at age 70 in BRCA1 carriers and 3% (0-7%) at age 50 and 15% (4-26%) at age 70 in BRCA2 carriers. The new model gave a better fit than the current default in BRCAPRO, the likelihood being 70 log units greater; in addition, the observed numbers of mutations in families stratified by gene and by cancer profile were not significantly different from those expected. Our new penetrance functions are appropriate for predicting breast cancer risk, and for determining the probability of carrying BRCA1/2 mutations, in people who are presently referred to genetic counseling in Italy. Our approach could lead to country-customized versions of the BRCAPRO software by providing appropriate population-specific estimates.

Germline mutations at BRCA1 or BRCA2 genes result in susceptibility to breast and ovarian cancers. BRCA1- and BRCA2-associated tumors have distinct histologic and molecular phenotypes, as compared to sporadic breast tumors. Typically, a higher grade of malignancy is observed in BRCA-associated cancers. A number of studies have suggested that BRCA1 and BRCA2 proteins are of importance in DNA repair and maintenance of genome integrity, bringing about molecular models of tumor pathogenesis. In particular, alterations at p53 gene have been suggested to be a necessary step in the tumorigenesis of BRCA-associated carcinomas. In fact, BRCA-associated breast cancers have higher p53 mutation frequencies than sporadic ones. At present, very little is known regarding BRCA non-associated familial tumors (termed BRCAx tumors). To our knowledge no data is available on p53 alterations in this sub-group of familial tumors. In this study p53 alteration frequencies were evaluated in 13 BRCA1, 11 BRCA2 and 55 BRCAx breast tumors. Tumor samples were analyzed for p53 gene mutations by PCR-SSCP/direct sequencing, and for p53 protein overexpression by immunohistochemistry (IHC). Altogether, p53 alterations were detected in 54% of BRCA1 tumors compared with 5% of BRCAx tumors. No p53 alteration was found in BRCA2 tumors. While loss of p53 checkpoint control is likely to be an important step in the molecular pathogenesis of BRCA1-associated cancers, our data seem to indicate a p53-independent molecular mechanism underlying BRCAx neoplastic transformation.

NM23.H1 is a protein connected with tumor progression. Loss of heterozygosity and reduced expression of the gene have been associated with poor prognosis and increased incidence of metastases in many epithelial tumors. The aim of this study was to detect the presence of NM23.H1 point mutations or small deletions in human breast carcinomas by using the single-strand-conformation polymorphism (SSCP) technique. Mutational analysis was performed on 76 breast tumors, 10 of which had allelic deletion of the gene. The NM23.H1 mRNA content also was evaluated in each sample. Only a C-to-A transversion leading to a stop codon was found in the 5' untranslated region of exon 1. A polymorphic SSCP pattern was identified in exon 1; direct sequencing showed a C-to-T transition 30 nucleotides upstream from the 5' splice site flanking exon 1. None of the tumors analyzed presented both alleles inactivated. Our results suggest that NM23.H1 is rarely inactivated by point mutations.

An altered control of the mechanisms involved in cell proliferation and programmed cell death (apoptosis) might play an important role in parathyroid tumorigenesis. We evaluated by immunohistochemistry the expression of bcl-2 and p53 proteins, as markers of apoptosis control, and MIB-1, as marker of cell proliferation, in a series of normal and neoplastic parathyroid tissues. The specimens were 33 normal parathyroids, 43 parathyroid adenomas and 3 parathyroid carcinomas. Results were scored as positive when more than 1% of cells were stained for MIB-1 and p53, and more than 10% for bcl-2. All normal parathyroids showed numerous bcl-2 positive cells (> or = 80%), low proliferation rate (MIB-1) and no p53 protein expression. Twenty-four (55%) adenomas were bcl-2 positive; in 16 of these the number of positive cells was high (> 50%) and immunoreactivity was diffusely distributed within the adenoma; 8 cases showed a zonal staining pattern, in which groups of stained cells were surrounded by negative cells. Nineteen adenomas (45%) and all carcinomas were bcl-2 negative. A high proliferative rate (MIB-1) was found in all carcinomas and 4 adenomas (9%); all MIB-1 positive adenomas were bcl-2 negative. p53 was negative in all specimens. No significant differences in serum calcium and intact PTH levels nor in tumor size were found between bcl-2 negative and bcl-2-positive and MIB-1-positive and MIB-1-negative adenomas. An inverse, but not statistically significant (p = 0.06) correlation was observed between the percentage of bcl-2 positive cells and serum calcium level in parathyroid adenomas. In conclusion, parathyroid adenomas are a heterogeneous group of lesions in which the pattern of bcl-2 and MIB-1 protein expression ranges between that of normal parathyroid (bcl-2 positivity and MIB-1 negativity) and that of parathyroid carcinoma (bcl-2 negativity and MIB-1 positivity). The question of whether the finding of the MIB-1 positive-bcl-2 negative phenotype identifies a subgroup of clinically more aggressive adenomas remains to be established.

NM23 is a protein associated with tumor progression, expressed in all tissues and in human tumors. Reduced expression of NM23.H I is related to high incidence of lymph node and distant metastasis or to poor prognosis of the patient in several human malignant tumors. In this study we analyze NM23 expression in non-neoplastic mammary tissues surrounding the tumoral lesions, in human mammary carcinomas and in lymph node metastasis. Our analysis shows that NM23.H I expression is lower in the mammary cells surrounding the tumor than in the tumor itself. In the primary tumors we observed a negative trend between degree of local invasion and level of NM23.H I expression. A further decrease of NM23.H I was detected in the invasive tumors that metastasized to axillary lymph nodes and in the metastasis. NM23.H2 was always more highly expressed than NM23.H1, and reduced expression of NM23.H1 but not NM23.H2 was concordant with the presence of lymph node metastasis or local invasiveness of the primary tumor. A positive correlation between NM23.H I mRNA content and cell growth rate of breast tumor cells has been confirmed. However, this trend was not maintained in cancer cells from tumors that metastasized to axillary lymph nodes and in metastatic cells; in these 2 situations the NM23.H1 mRNA content varied without any relationship to the proliferative rate of the cells. In addition, in comparison with the initial tumor, the metastatic cell population showed a strong decrease of NM23.H1 expression and increased proliferative activity.

The NM23 gene, involved in the negative regulation of metastatic progression, has been found to be highly homologous to developmentally regulated genes such as the awd gene in Drosophila melanogaster and the Gip17 gene in Dyctiostelium discoideum. To ascertain whether the NM23 genes are involved in the differentiation processes of human cell lines, the NM23.H1 and NM23.H2 expression level has been determined during the monocyte-macrophage differentiation of HL-60 and U-937 cell lines induced by vitamin D3. In both lines, vitamin D3 produced induction of differentiate markers, inhibition of cell proliferation and a decrease of the NM23.H1, NM23.H2 and c-myc genes, behaving both as a differentiative and an antiproliferative agent. The fact that the c-myc transcriptional factor PuF is identical to the NM23.H2 gene and that NM23 protein could be a transcriptional factor suggests that the regulatory action exerted by vitamin D3 on c-myc transcription is mediated by NM23.H2.

BRCA1, the predisposing gene for familial breast and ovarian cancer localized on chromosome 17q21.3 has been recently cloned. The gene comprises 22 coding exons which span 100 kB of genomic sequence. The protein predicted is 1863 aminoacids long. 31 mutations have been identified in constitutional DNA of affected member from various family of which 22 were distinct. Not one of 22 transcribed exons seems to be a preferential target site for mutations. Overall germline BRCA1 mutations account for 1–2% of all breast cancers and about 3% of ovarian cancers. The lifetime risk of breast and ovarian cancer in BRCA1 mutation carriers is high: the risk of breast cancer is about 50% by age 50 and 70% by age 70. The average risk of ovarian cancer is 40% by age 70. BRCA1 has never been found mutated in sporadic carcinomas, however, loss of heterozigosity in the region of BRCA1 has been observed in 40% of breast and about 60% of ovarian cancers. The lifetime risk to develop the familial form of the disease may be calculated by identifying mutations in BRCA1 or BRCA2 genes. From the screening of 1100 medical records of patients subjected to mastectomy in S. Chiara Hospital in Pisa during the period 1990–1994, the patients with a referred familial recurrence of breast or ovarian cancer were selected for interview. 81 patients belonging to 75 families fitted the BRCA1 eligibility criteria. 37 patients belonging to different families were analyzed for BRCA1 germline mutation. All 37 families are Caucasian and principally reside in Tuscany. Mutation screening was done by ASO (allelic specific oligo hybridization) for three common mutations and by direct sequencing of each of the coding exons. The analysis is under way and approximately 50% ofthe coding region has been screened up to now. We have so far identified 7 mutations of which 5 are different. Three are frameshift and 2 missense. Only one of the mutations found has been reported previously (5382insC). The insertion of an A has been reported in three different families, the aplotype analysis has been performed to ascertain if a common ancestor exist for those three families. No evident correlation between phenotype and genotype has been detected. CG and GC are fellows of the Italian Association for Cancer Research. This work was supported by AIRC and CNR PF ACRO grants.

Incubation of leech segmental ganglia with [ 32 P]phosphoric acid results in the labeling of 30 phosphoproteins, detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, followed by autoradiography. Treatment with 8-bromo-cAMP or phosphodiesterase inhibitors induces a rise in the label of the following phosphoproteins: 96, 79, 63, 50, 40, 32, 28, 24, 23 and 20 kDa. One of the most intersting membrane-bound proteins studied has an apparent molecular weight of 79 kDa. It seems to be specific for the nervous tissue and inside the nervous system, for segmental ganglia. The role of these phosphoproteins in the mechanisms of learning processes is discussed.

Deleterious mutations of the BRCA1 and BRCA2 genes are a major risk factor for the development of breast and ovarian cancers.1–4 Mutation tests for these two genes commonly are now offered in specialised clinics.5,6 As a result, a large number of women with personal or family histories of breast or ovarian cancer seek genetic counselling. Accurate evaluation of the probability that a woman carries a germline pathogenic mutation at BRCA1 or BRCA2 therefore is essential to help counsellors and those being counselled to decide whether testing is appropriate. In this context, the questions of practical interest are: Given the pedigree, what is the chance of a mutation being present? and What is the chance of the DNA laboratory finding a mutation? After testing became available, several models were developed to assess the pre-test probability of identifying carriers of mutations. Broadly speaking, two different approaches have been used to develop predictive models: the “empirical approach” and the “Mendelian approach”.7 In empirical models, families are stratified according to variables that describe their family history; regression or other approaches are used to predict the results of Mendelian testing. In some cases, this approach simply consists of observing the proportion of mutations found in different strata. Mendelian models, in contrast, address the probability that a proband is a mutation carrier on the basis of explicit assumptions about the genetic parameters (allele frequencies and cancer penetrances in carriers and non-carriers) and the Mendelian rules of gene transmission. A consequence of the two different strategies is that the Mendelian models evaluate the probability that a proband is a gene carrier, whereas the empirical models evaluate the probability of identifying a mutation. The main purpose of this study was to compare the performances of published models in predicting mutation test results in …