Melbourne School of Population and Global Health - Research Publications

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    Identification of new breast cancer predisposition genes via whole exome sequencing
    Southey, MC ; Park, DJ ; Lesueur, F ; Odefrey, F ; Nguyen-Dumont, T ; Hammet, F ; Neuhausen, SL ; John, EM ; Andrulis, IL ; Chenevix-Trench, G ; Baglietto, L ; Le Calvez-Kelm, F ; Pertesi, M ; Lonie, A ; Pope, B ; Sinilnikova, O ; Tsimiklis, H ; Giles, GG ; Hopper, JL ; Tavtigian, SV ; Goldgar, DE (Springer Science and Business Media LLC, 2012-01)
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    Prevalence of PALB2 mutations in Australasian multiple-case breast cancer families
    Teo, ZL ; Park, DJ ; Provenzano, E ; Chatfield, CA ; Odefrey, FA ; Tu, N-D ; Dowty, JG ; Hopper, JL ; Winship, I ; Goldgar, DE ; Southey, MC (BMC, 2013)
    INTRODUCTION: Population-based studies of breast cancer have estimated that some PALB2 mutations confer a breast cancer risk (penetrance) comparable to the average pathogenic mutation in BRCA2. As this risk is of clinical relevance, we sought to identify mono-allelic PALB2 mutations and determine their frequencies in multiple-case breast cancer families attending Familial Cancer Clinics in Australia and New Zealand. METHODS: The youngest affected woman, not known to carry a mutation in BRCA1 or BRCA2, from 747 multiple-case breast cancer families participating in kConFab were selected for PALB2 mutation screening. The coding and flanking intronic regions of PALB2 in DNA extracted from blood were screened using high-resolution melt curve analysis with Sanger sequencing confirmation. Where possible, relatives of women found to carry PALB2 mutations were genotyped for the family-specific mutation, mutant transcripts were characterised and breast tumours arising in mutation carriers were recalled and reviewed. Missense mutations were assessed for potential to disrupt protein function via SIFT, Align GVGD and Polyphen-2. RESULTS: The mutation screen identified two nonsense mutations (PALB2 c.3113G>A in eight women and PALB2 c.196C>T in one woman), two frameshift mutations (PALB2 c.1947_1948insA and PALB2 c.2982_2983insT each in one woman), 10 missense variants, eight synonymous variants and four variants in intronic regions. Of the four PALB2 mutations identified that were predicted to produce truncated protein products, only PALB2 c.1947_1948insA had not previously been reported. PALB2 c.3113G>A and PALB2 c.196C>T were previously identified in the Australian population whereas PALB2 c.2982_2983insT was previously reported in the UK population. Transcripts derived from three of these mutant PALB2 alleles were vulnerable to nonsense-mediated decay. One missense mutation (PALB2 c.2993G>A) was predicted to disrupt protein function via the three in silico assessment methods applied. The majority of breast cancers arising in carriers that were available for review were high-grade invasive ductal carcinomas. CONCLUSIONS: About 1.5% (95% CI 0.6to 2.4) of Australasian multiple-case breast cancer families attending clinics are segregating protein-truncating mutations in PALB2, most being PALB2 c.3113G>A, p.Trp1038*. Given the prevalence, breast cancer risk, and tumour grade associated with this mutation, consideration of clinical PALB2 testing is warranted.
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    Is RNASEL:p.Glu265*a modifier of early-onset breast cancer risk for carriers of high-risk mutations?
    Nguyen-Dumont, T ; Teo, ZL ; Hammet, F ; Roberge, A ; Mahmoodi, M ; Tsimiklis, H ; Park, DJ ; Pope, BJ ; Lonie, A ; Kapuscinski, MK ; Mahmood, K ; Goldgar, DE ; Giles, GG ; Winship, I ; Hopper, JL ; Southey, MC (BIOMED CENTRAL LTD, 2018-02-08)
    BACKGROUND: Breast cancer risk for BRCA1 and BRCA2 pathogenic mutation carriers is modified by risk factors that cluster in families, including genetic modifiers of risk. We considered genetic modifiers of risk for carriers of high-risk mutations in other breast cancer susceptibility genes. METHODS: In a family known to carry the high-risk mutation PALB2:c.3113G>A (p.Trp1038*), whole-exome sequencing was performed on germline DNA from four affected women, three of whom were mutation carriers. RESULTS: RNASEL:p.Glu265* was identified in one of the PALB2 carriers who had two primary invasive breast cancer diagnoses before 50 years. Gene-panel testing of BRCA1, BRCA2, PALB2 and RNASEL in the Australian Breast Cancer Family Registry identified five carriers of RNASEL:p.Glu265* in 591 early onset breast cancer cases. Three of the five women (60%) carrying RNASEL:p.Glu265* also carried a pathogenic mutation in a breast cancer susceptibility gene compared with 30 carriers of pathogenic mutations in the 586 non-carriers of RNASEL:p.Glu265* (5%) (p < 0.002). Taqman genotyping demonstrated that the allele frequency of RNASEL:p.Glu265* was similar in affected and unaffected Australian women, consistent with other populations. CONCLUSION: Our study suggests that RNASEL:p.Glu265* may be a genetic modifier of risk for early-onset breast cancer predisposition in carriers of high-risk mutations. Much larger case-case and case-control studies are warranted to test the association observed in this report.