Assessing biases of information contained in pedigrees for the classification of BRCA-genetic variants: a study arising from the ENIGMA analytical working group

A Pragmatic Testing-Eligibility Framework for Population Mutation Screening: The Example of BRCA1/2

BACKGROUND

Eligibility guidelines for genetic testing may be revisited, given technological advances, plummeting costs, and proposals for population mutation screening. A key property of eligibility criteria is the tradeoff between the number of mutation carriers identified versus population members tested. We assess the fractions of mutation carriers identified, versus women undergoing mutation testing, for BRCA1/2 founder mutation screening in U.S. Ashkenazi-Jewish women.

METHODS

BRCA1/2 carrier probabilities, based on personal/family history, were calculated using the risk-prediction tool BRCAPRO for 4,589 volunteers (102 mutation carriers) in the population-based Washington Ashkenazi Study. For each carrier-probability threshold between 0% and 10%, we compared the percentage of founder mutations detected versus the percentage of women requiring mutation testing. PCR mutation testing was conducted at the NIH for the 3 Ashkenazi-Jewish founder mutations (5382insC and 185delAG in BRCA1, and 6174delT in BRCA2).

RESULTS

Identifying 90% of BRCA1/2 founder mutations required testing the 60% of Ashkenazi-Jewish women with carrier probabilities exceeding 0.56%, potentially avoiding mutation testing for approximately 0.7 to 1.1 million U.S. Ashkenazi-Jewish women. Alternatively, testing the 44% whose carrier probability exceeded 0.78% identified 80% of mutation carriers, increasing to 89% of mutation carriers when accounting for cascade testing triggered after mutation-positive daughters were identified by screening. We present data on all carrier-probability thresholds, e.g., a 5% threshold identified 46% of mutation carriers while testing 10% of women.

CONCLUSIONS

Different carrier-probability thresholds offered diverse tradeoffs between numbers of identified mutation carriers versus women tested. Low carrier-probability thresholds identified 90% of BRCA1/2 founder mutation carriers, without testing approximately 1 million U.S. Ashkenazi-Jewish women with lowest carrier probabilities.

IMPACT

In general, this risk-based framework could provide useful new options to consider during eligibility-criteria development for population mutation screening.

Combined annotation-dependent depletion score for BRCA1/2 variants in patients with breast and/or ovarian cancer

Utility of combined annotation‐dependent depletion (CADD) score was recently reported to rank pathogenicity as C‐scores ranging 1‐99 for both confirmed deleterious mutation. Using C‐scores for BRCA1/2 variants, we tried to constitute the classification system for variant of uncertain significance (VUS), which had been a major problem of genetic testing for hereditary breast and/or ovarian cancer. We analyzed BRCA1/2 genes for 283 patients with breast and/or ovarian cancer. The deleterious mutation and missesne mutations, minor variant, and wild type of BRCA1 and ‐2 were 5, 27, 251 and 15, 85, 183, respectively. Meanwhile, the variants with C‐score ≥10 were involved in 19/283 (6.7%) in BRCA1 and 34/283 (12%) in BRCA2. All deleterious mutations were included in this group. Frequency of personal history and family history of ovarian cancer were significantly high, and frequency of serous adenocarcinoma of ovary and triple negative breast cancer was relatively high in the group with deleterious mutations. Similar findings were seen in patients with variants of C‐score ≥10. According to the C‐score and population frequency, we could define VUS for 11 patients out of 283 patients (3.9 CADD is useful to classify the variant of BRCA1/2 and selecting the patient who needs further segregation studies.

Systems approaches in osteoarthritis: Identifying routes to novel diagnostic and therapeutic strategies

Systems orientated research offers the possibility of identifying novel therapeutic targets and relevant diagnostic markers for complex diseases such as osteoarthritis. This review demonstrates that the osteoarthritis research community has been slow to incorporate systems orientated approaches into research studies, although a number of key studies reveal novel insights into the regulatory mechanisms that contribute both to joint tissue homeostasis and its dysfunction. The review introduces both top-down and bottom-up approaches employed in the study of osteoarthritis. A holistic and multiscale approach, where clinical measurements may predict dysregulation and progression of joint degeneration, should be a key objective in future research. The review concludes with suggestions for further research and emerging trends not least of which is the coupled development of diagnostic tests and therapeutics as part of a concerted effort by the osteoarthritis research community to meet clinical needs. © 2017 The Authors. Journal of Orthopaedic Research Published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 35:1573-1588, 2017.

Classification of the spliceogenic BRCA1 c.4096+3A>G variant as likely benign based on cosegregation data and identification of a healthy homozygous carrier

BRCA1, c.4096+3A>G was identified in a consanguineous Danish family with several cases of breast/ovarian cancer. In silico analysis and splicing assays indicated that the variant caused aberrant splicing. However, based on segregation data and the finding of a healthy homozygous carrier, we classify the BRCA1 c.4096+3A>G variant as likely benign.