Genome-Wide Association Study in BRCA1 Mutation Carriers Identifies Novel Loci Associated with Breast and Ovarian Cancer Risk

BRCA1-associated breast and ovarian cancer risks can be modified by common genetic variants. To identify further cancer risk-modifying loci, we performed a multi-stage GWAS of 11,705 BRCA1 carriers (of whom 5,920 were diagnosed with breast and 1,839 were diagnosed with ovarian cancer), with a further replication in an additional sample of 2,646 BRCA1 carriers. We identified a novel breast cancer risk modifier locus at 1q32 for BRCA1 carriers (rs2290854, P = 2.7×10-8, HR = 1.14, 95% CI: 1.09-1.20). In addition, we identified two novel ovarian cancer risk modifier loci: 17q21.31 (rs17631303, P = 1.4×10-8, HR = 1.27, 95% CI: 1.17-1.38) and 4q32.3 (rs4691139, P = 3.4×10-8, HR = 1.20, 95% CI: 1.17-1.38). The 4q32.3 locus was not associated with ovarian cancer risk in the general population or BRCA2 carriers, suggesting a BRCA1-specific associat

Exome sequencing identifies rare damaging variants in ATP8B4 and ABCA1 as risk factors for Alzheimer’s disease

Alzheimer’s disease (AD), the leading cause of dementia, has an estimated heritability of approximately 70%1. The genetic component of AD has been mainly assessed using genome-wide association studies, which do not capture the risk contributed by rare variants2. Here, we compared the gene-based burden of rare damaging variants in exome sequencing data from 32,558 individuals—16,036 AD cases and 16,522 controls. Next to variants in TREM2, SORL1 and ABCA7, we observed a significant association of rare, predicted damaging variants in ATP8B4 and ABCA1 with AD risk, and a suggestive signal in ADAM10. Additionally, the rare-variant burden in RIN3, CLU, ZCWPW1 and ACE highlighted these genes as potential drivers of respective AD-genome-wide association study loci. Variants associated with the strongest effect on AD risk, in particular loss-of-function variants, are enriched in early-onset AD cases. Our results provide additional evidence for a major role for amyloid-β precursor protein processing, amyloid-β aggregation, lipid metabolism and microglial function in AD

The Influence of Number and Timing of Pregnancies on Breast Cancer Risk for Women With BRCA1 or BRCA2 Mutations

Background: Full-term pregnancy (FTP) is associated with a reduced breast cancer (BC) risk over time, but women are at increased BC risk in the immediate years following an FTP. No large prospective studies, however, have examined whether the number and timing of pregnancies are associated with BC risk for BRCA1 and BRCA2 mutation carriers. Methods: Using weighted and time-varying Cox proportional hazards models, we investigated whether reproductive events are associated with BC risk for mutation carriers using a retrospective cohort (5707 BRCA1 and 3525 BRCA2 mutation carriers) and a prospective cohort (2276 BRCA1 and 1610 BRCA2 mutation carriers), separately for each cohort and the combined prospective and retrospective cohort. Results: For BRCA1 mutation carriers, there was no overall association with parity compared with nulliparity (combined hazard ratio [HRc] ¼ 0.99, 95% confidence interval [CI] ¼ 0.83 to 1.18). Relative to being uniparous, an increased number of FTPs was associated with decreased BC risk (HRc¼ 0.79, 95% CI ¼ 0.69 to 0.91; HRc¼ 0.70, 95% CI ¼ 0.59 to 0.82; HRc¼ 0.50, 95% CI ¼ 0.40 to 0.63, for 2, 3, and 4 FTPs, respectively, Ptrend < .0001) and increasing duration of breastfeeding was associated with decreased BC risk (combined cohort Ptrend ¼ .0003). Relative to being nulliparous, uniparous BRCA1 mutation carriers were at increased BC risk in the prospective analysis (prospective hazard ration [HRp] ¼ 1.69, 95% CI ¼ 1.09 to 2.62). For BRCA2 mutation carriers, being parous was associated with a 30% increase in BC risk (HRc ¼ 1.33, 95% CI ¼ 1.05 to 1.69), and there was no apparent decrease in risk associated with multiparity except for having at least 4 FTPs vs. 1 FTP (HRc¼ 0.72, 95% CI ¼ 0.54 to 0.98). Conclusions: These findings suggest differential associations with parity between BRCA1 and BRCA2 mutation carriers with higher risk for uniparous BRCA1 carriers and parous BRCA2 carriers

Effect of normobaric hyperoxia on antioxidant defenses of hela and CHO cells

The effect of increased intracellular oxygen activation on cellular antioxidant defenses in CHO and HeLa cells was studied. In both cell types, hyperoxic exposure (up to 4 days, 600-700 mm Hg O2) and in CHO cells menadione (up to 3 days, 15 μM) failed to affect the enzymatic antioxidant defenses Mn-containing superoxide dismutase (Mn-SOD), CuZn-SOD, catalase and glutathione peroxidase. The markedly increased antioxidant enzyme activities observed in a recently obtained oxygen-tolerant CHO variant persisted under normoxia. These data suggest that the synthesis of antioxidant enzymes is constitutive. Glutathione levels of HeLa cells did not respond to hyperoxia whereas in CHO cells hyperoxia and menadione exposure resulted in a 2- and 7-fold increase in glutathione contents, respectively. However, considering the large variations in glutathione contents observed under normal culture conditions, it is uncertain whether this increase is to be considered as a true adaptive response

Influence of the antioxidant N-acetylcysteine and its metabolites on damage induced by bleomycin in PM2 bacteriophage DNA

Bleomycin is considered to be a useful model compound for studying environmental carcinogenesis, due to its broad spectrum of DNA damaging properties. In addition, bleomycin is a useful antitumor drug because of its cytotoxic properties. To investigate the influence of the antioxidant N-acetylcysteine and its metabolites glutathione and cysteine on bleomycin-induced DNA damage and more importantly to gain insight into the biological relevance of such damage. PM2 DNA was exposed to Cu2+-bleomycin in the presence and absence of the thiols N-acetylcysteine, glutathione and cysteine. It was found that the presence of these thiols led to a considerable enhancement of bleomycin-induced single- and double-strand breaks and a concomitant decrease in the biological activity of PM2 DNA in a dose-dependent way. A similar observation was made when ascorbic acid was used. Bleomycin showed no DNA damaging activity when PM2 DNA was pretreated with the strong Fe ion chelator desferal and its activity was strongly inhibited by the addition of CU2+ ions or under hypoxic (N2) conditions. Cu2+-bleomycin under our conditions is not active by itself, but most probably after binding to DNA exchanges CU2+ for Fe3+ bound to DNA. Fe3+-bleomycin is then reduced to Fe2+-bleomycin, a process potentiated by the added antioxidants, and subsequently activated by O2. The contribution to biological inactivation of bleomycin alone or in the presence of ascorbic acid is only ~15%. The contribution to lethality in the presence of thiols is higher. These results indicate that ascorbic acid only enhances the DNA damaging properties of bleomycin, whereas the thiol compounds in addition influence the type of DNA damage. The remainder of the biological inactivation is probably caused by double damage, such as single-strand breaks with closely opposed alkali-labile sites or base damage

An autosomal dominant high bone mass phenotype in association with craniosynostosis in an extended family is caused by an **LRP5** missense mutation

Gain-of-function mutations in LRP5 have been shown to cause high BMD disorders showing variable expression of some clinical symptoms, including torus palatinus and neurological complications. In an extended family, we were able to add craniosynostosis and developmental delay to the clinical spectrum associated with LRP5 mutations. We report on an extended four-generation family with 13 affected individuals (7 men and 6 women) in which an autosomal dominant type of osteosclerosis segregates. Osteosclerosis was most pronounced in the cranial base and calvarium, starting in early childhood with variable expression and a progressive character. Craniosynostosis at an early age was reported in four affected family members (two males and two females). The patients also presented with dysmorphic features (macrocephaly, brachycephaly, wide and high forehead, hypertelorism, prominent cheekbones, prominent jaw). They have normal height and proportions. Neurological complications like entrapment of cranial nerves resulting in optical nerve atrophy, hearing loss, and facial palsy were reported in two individuals. A mild developmental delay was reported in three affected individuals. None of the patients have torus palatinus, increased rate of fractures, osteomyelitis, hepatosplenomegaly, or pancytopenia. A missense mutation 640G-->A (A214T) in the low-density lipoprotein receptor-related protein 5 (LRP5) gene was found in all affected individuals analyzed, including cases in whom craniosynostosis, a mild developmental delay, and/or macrocephaly is observed. To our knowledge, this is the first report in the literature of patients presenting with autosomal dominant osteosclerosis in whom a variable expression of craniosynostosis, macrocephaly, and mild developmental delay is observed, which is most likely associated with a mutation in the LRP5 gene. These phenotypes can therefore be added to the clinical spectrum of LRP5-associated bone disorders

Serum CA-125 in relation to adnexal dysplasia and cancer in women at hereditary high risk of ovarian cancer

Purpose: Serum CA-125 level is commonly used as indicator for ovarian cancer recurrence. However, its value for the prediction of neoplastic lesions is unknown. The aim of this study was to investigate whether CA-125 concentrations are indicative of adnexal dysplasia and cancer in women at hereditary high risk of ovarian/tubal cancer. Patients and Methods: CA-125 was obtained from 424 women at hereditary high risk of ovarian/tubal cancer attending the VU University Medical Center (Amsterdam, the Netherlands) between 1993 and 2005. Serum samples obtained at the second-to-last (n = 64) and last (n = 98) visit before surgery were tested in women who underwent adnexal surgery for diagnostic (n = 9) or prophylactic (n = 89) reasons. Serum samples obtained from 370 age-matched healthy women were used as controls. Results: Both the absolute value (P < .0001) and the serial change (P < .0001) of CA-125 were predictive for ovarian cancer (n = 8). For adnexal dysplasia (n = 23), the absolute value of CA-125 (P = .003) was predictive, but the serial change in CA-125 was not (P = .32). The odds ratio for adnexal dysplasia versus nondysplasia in the highest tertile (CA-125 levels ≥ 14 U/mL) compared with the lowest tertile (CA-125 < 10 U/mL) was 6 (95% CI, 1.32 to 36.66). Conclusion: In patients at hereditary high risk for adnexal cancer, both the absolute value of serum CA-125 and the change in serial CA-125 are predictors for ovarian cancer. Remarkably, the absolute value of CA-125 is also predictive for adnexal dysplasia. CA-125 values should, therefore, be taken into account in the decision toward prophylactic bilateral salpingo-oophorectomy

Low prevalence of (pre) malignant lesions in the breast and high prevalence in the ovary and fallopian tube in women at hereditary high risk of breast and ovarian cancer

To analyse the prevalence of (pre) malignant lesions occurring in breast and adnexal tissue at prophylactic surgery in women at hereditary high risk of breast and/or ovarian cancers. Tissue was obtained from 85 women who underwent prophylactic bilateral salpingo-oophorectomy (pBSO) and from 59 women who underwent prophylactic mastectomy (pM). Control tissue samples were obtained from women undergoing breast reduction surgery (N = 99) or adnexal surgery for benign reasons (N = 72). In women with a BRCA1/2 mutation, the prevalence of a (pre) malignant adnexal lesion was 50% (95% CI 26-74) if older than 40 years and 14% (95% CI 0-58) if younger. The prevalences of (pre) malignant breast lesions in women older than 40 years, with and without a BRCA1/2 mutation, were 0% (95% CI 0-16) and 47% (95% CI 21-73), respectively. No association was found between (pre) malignant lesions in breast and adnexal tissue occurring in 28 women who underwent surgery on both organs (R = 0.155, p = 0.432), but the prevalence of lesions was significantly higher in adnexal tissue than in the breast (p = 0.023). Compared to controls, women at hereditary high risk had a higher chance of (pre) malignant lesions in the breast and an even higher chance of such lesions in the adnexal tissue. There was no indication for concomitant presence of such lesions in both organs at the time of prophylactic surgery. The high frequency of (pre) malignant lesions in the adnexal tissue stresses further the importance of pBSO from the age of 40 onwards in women at hereditary high risk

Familial multiple discoid fibromas is linked to a locus on chromosome 5 including the FNIP1 gene

Previously, we reported a series of families presenting with trichodiscomas, inherited in an autosomal dominant pattern. The phenotype was named familial multiple discoid fibromas (FMDF). The genetic cause of FMDF remained unknown so far. Trichodiscomas are skin lesions previously reported to be part of the same spectrum as the fibrofolliculoma observed in Birt-Hogg-Dubé syndrome (BHD), an inherited disease caused by pathogenic variants in the FLCN gene. Given the clinical and histological differences with BHD and the exclusion of linkage with the FLCN locus, the phenotype was concluded to be distinct from BHD. We performed extensive clinical evaluations and genetic testing in ten families with FMDF. We identified a FNIP1 frameshift variant in nine families and genealogical studies showed common ancestry for eight families. Using whole exome sequencing, we identified six additional rare variants in the haplotype surrounding FNIP1, including a missense variant in the PDGFRB gene that was found to be present in all tested patients with FMDF. Genome-wide linkage analysis showed that the locus on chromosome 5 including FNIP1 was the only region reaching the maximal possible LOD score. We concluded that FMDF is linked to a haplotype on chromosome 5. Additional evaluations in families with FMDF are required to unravel the exact genetic cause underlying the phenotype. When evaluating patients with multiple trichodisomas without a pathogenic variant in the FLCN gene, further genetic testing is warranted and can include analysis of the haplotype on chromosome 5