Validation of the pedigree assessment tool (PAT) in families with BRCA1 and BRCA2 mutations.

BACKGROUND: The lifetime risk of breast cancer (BC) in patients with hereditary breast cancer syndromes is as high as 80%. The Pedigree Assessment Tool (PAT) is a scoring system to aid in identifying these patients. This validation study compares the PAT to BRCA gene mutation probability models in predicting suitability for genetic referral. METHODS: Retrospective review identified subjects undergoing genetic counseling and BRCA testing from 2001 to 2008 at two institutions. PAT score and BRCA mutation probabilities were calculated using Myriad II and Penn II models. Comparisons were made between models in ability to discriminate patients appropriate for genetic evaluation based on accuracy in predicting a positive test result. RESULTS: Records evaluated represent 520 families. BRCA testing revealed 146 mutation-positive and 374 mutation-negative families. c-Statistic analysis was used to compare the discriminating ability of the models to correctly assign families as mutation (+) and (-). Both the PAT and Penn II model outperformed the Myriad II model. Using a threshold PAT score >or=8 and mutation probability >or=10% to assign families as mutation (+) versus (-), sensitivity, specificity, and positive and negative predictive values were calculated for each model. The PAT was more sensitive than the Myriad II model and more specific than the Penn II model. CONCLUSIONS: In overall performance, the PAT is at least comparable to the Myriad II and Penn II models in screening women appropriate for genetic referral. Simplicity and identification of families with non-BRCA hereditary BC syndromes suggest that the PAT is better suited for BC risk screening.

Assessment and counseling for women with a family history of breast cancer. A guide for clinicians.

More women in all risk categories are seeking information regarding their individual breast cancer risk, and there is a need for their primary care clinicians to be able to assess familial risk factors for breast cancer, provide individualized risk information, and offer surveillance recommendations. Estimates of the number of women with a family history of breast cancer range from approximately 5% to 20%, depending on the population surveyed. Many of these women will not have a family history that suggests the presence of a highly penetrant breast cancer susceptibility gene. However, a small subset of such women will come from families with a striking incidence of breast and other cancers often associated with inherited mutations. The development and refinement of risk prediction models provide an epidemiologic basis for counseling women with a family history that does not appear related to a dominant susceptibility gene. contrast, the recent isolation of BRCA1, the localization of BRCA2, and the acknowledgement that additional breast cancer susceptibility genes must exist provide a molecular basis for counseling some high-risk women. We present a guide for primary care clinicians that may be helpful in defining families as moderate or high risk, in determining individual risk in women with a family history of breast cancer based on this distinction, and for counseling women in a setting where the data necessary to design surveillance and prevention strategies are lacking. We include criteria for selecting women who may be candidates for detection of inherited mutations in breast cancer susceptibility genes.

Mutations in the BRCA1 gene in families with early-onset breast and ovarian cancer.

We analysed 50 probands with a family history of breast and/or ovarian cancer for germline mutations in the coding region of the BRCA1 candidate gene, using single-strand conformation polymorphism (SSCP) analysis on PCR-amplified genomic DNA. A total of eight putative disease-causing alterations were identified: four of these are frameshifts and two are nonsense mutations. In addition, we found two missense mutations, one of which changes the final cysteine of the BRCA1 zinc finger motif to glycine. These data are consistent with a tumour suppressor model, and support the notion that this candidate gene is in fact BRCA1. The heterogeneity of mutations, coupled with the large size of the gene, indicates that clinical application of BRCA1 mutation testing will be technically challenging.

Identification and characterization of a new surface membrane antigen found predominantly on malignant B lymphocytes.

A monoclonal antibody, 1D10, was derived that identifies a new antigenic epitope on the surface of malignant B lymphocytes. Normal resting and stimulated lymphocytes do not express the antigen. The majority of individuals with acute Epstein-Barr virus infection express the antigen on their lymphocytes, and in these patients, the T lymphocyte may also be antigen positive. The antigen was found on B-lymphoid neoplasia from the early pre-B cell stage through terminally differentiated plasma cells, a characteristic not reported for other B cell-associated antigens. Studies on homozygous typing cells and cells from individuals with known HLA phenotypes indicate that the antigen does not segregate in a pattern characteristic for major histocompatibility antigens. The molecule is a heterodimeric polypeptide with the molecular weight and isoelectric points of the alpha and beta chains being 32,000 d/4 and 28,000 d/6, respectively. Evidence is presented that the 1D10 molecule is not HLA-DR, -DP, or -DQ. By extrapolation, we suggest that this novel molecule may represent HLA D-region gene expression of a gene(s) not normally expressed. Potential candidates are D-region pseudogenes. We conclude that the antigenic epitope identified by the 1D10 monoclonal antibody is unique among previously described B-lymphocyte antigens. Further studies of the factors controlling the expression of this molecule, as well as studies designed to look at the possible cellular function, may provide insights for understanding crucial events in the malignant transformation of lymphocytes.