Inherited loss-of-function mutations in BRCA1 and BRCA2 and other tumor suppressor genes predispose to ovarian carcinomas, but the overall burden of disease due to inherited mutations is not known. ...Using targeted capture and massively parallel genomic sequencing, we screened for germ-line mutations in 21 tumor suppressor genes in genomic DNA from women with primary ovarian, peritoneal, or fallopian tube carcinoma. Subjects were consecutively enrolled at diagnosis and not selected for age or family history. All classes of mutations, including point mutations and large genomic deletions and insertions, were detected. Of 360 subjects, 24% carried germ-line loss-of-function mutations: 18% in BRCA1 or BRCA2 and 6% in BARD1, BRIP1, CHEK2, MRE11A, MSH6, NBN, PALB2, RAD50, RAD51C, or TP53. Six of these genes were not previously implicated in inherited ovarian carcinoma. Primary carcinomas were generally characterized by genomic loss of normal alleles of the mutant genes. Of women with inherited mutations, >30% had no family history of breast or ovarian carcinoma, and >35% were 60 y or older at diagnosis. More patients with ovarian carcinoma carry cancer-predisposing mutations and in more genes than previously appreciated. Comprehensive genetic testing for inherited carcinoma is warranted for all women with ovarian, peritoneal, or fallopian tube carcinoma, regardless of age or family history. Clinical genetic testing is currently done gene by gene, with each test costing thousands of dollars. In contrast, massively parallel sequencing allows such testing for many genes simultaneously at low cost.
Inherited loss-of-function mutations in the tumor suppressor genes BRCA1, BRCA2, and multiple other genes predispose to high risks of breast and/or ovarian cancer. Cancer-associated inherited ...mutations in these genes are collectively quite common, but individually rare or even private. Genetic testing for BRCA1 and BRCA2 mutations has become an integral part of clinical practice, but testing is generally limited to these two genes and to women with severe family histories of breast or ovarian cancer. To determine whether massively parallel, "next-generation" sequencing would enable accurate, thorough, and cost-effective identification of inherited mutations for breast and ovarian cancer, we developed a genomic assay to capture, sequence, and detect all mutations in 21 genes, including BRCA1 and BRCA2, with inherited mutations that predispose to breast or ovarian cancer. Constitutional genomic DNA from subjects with known inherited mutations, ranging in size from 1 to >100,000 bp, was hybridized to custom oligonucleotides and then sequenced using a genome analyzer. Analysis was carried out blind to the mutation in each sample. Average coverage was >1200 reads per base pair. After filtering sequences for quality and number of reads, all single-nucleotide substitutions, small insertion and deletion mutations, and large genomic duplications and deletions were detected. There were zero false-positive calls of nonsense mutations, frameshift mutations, or genomic rearrangements for any gene in any of the test samples. This approach enables widespread genetic testing and personalized risk assessment for breast and ovarian cancer.
Hallmarks of germline BRCA1/2-associated ovarian carcinomas include chemosensitivity and improved survival. The therapeutic impact of somatic BRCA1/2 mutations and mutations in other homologous ...recombination DNA repair genes is uncertain.
Using targeted capture and massively parallel genomic sequencing, we assessed 390 ovarian carcinomas for germline and somatic loss-of-function mutations in 30 genes, including BRCA1, BRCA2, and 11 other genes in the homologous recombination pathway.
Thirty-one percent of ovarian carcinomas had a deleterious germline (24%) and/or somatic (9%) mutation in one or more of the 13 homologous recombination genes: BRCA1, BRCA2, ATM, BARD1, BRIP1, CHEK1, CHEK2, FAM175A, MRE11A, NBN, PALB2, RAD51C, and RAD51D. Nonserous ovarian carcinomas had similar rates of homologous recombination mutations to serous carcinomas (28% vs. 31%, P = 0.6), including clear cell, endometrioid, and carcinosarcoma. The presence of germline and somatic homologous recombination mutations was highly predictive of primary platinum sensitivity (P = 0.0002) and improved overall survival (P = 0.0006), with a median overall survival of 66 months in germline homologous recombination mutation carriers, 59 months in cases with a somatic homologous recombination mutation, and 41 months for cases without a homologous recombination mutation.
Germline or somatic mutations in homologous recombination genes are present in almost one third of ovarian carcinomas, including both serous and nonserous histologies. Somatic BRCA1/2 mutations and mutations in other homologous recombination genes have a similar positive impact on overall survival and platinum responsiveness as germline BRCA1/2 mutations. The similar rate of homologous recombination mutations in nonserous carcinomas supports their inclusion in PARP inhibitor clinical trials.
Massively parallel sequencing of targeted regions, exomes, and complete genomes has begun to dramatically increase the pace of discovery of genes responsible for human disorders. Here we describe how ...exome sequencing in conjunction with homozygosity mapping led to rapid identification of the causative allele for nonsyndromic hearing loss DFNB82 in a consanguineous Palestinian family. After filtering out worldwide and population-specific polymorphisms from the whole exome sequence, only a single deleterious mutation remained in the homozygous region linked to DFNB82. The nonsense mutation leads to an early truncation of the G protein signaling modulator GPSM2, a protein that is essential for maintenance of cell polarity and spindle orientation. In the mouse inner ear, GPSM2 is localized to apical surfaces of hair cells and supporting cells and is most highly expressed during embryonic development. Identification of GPSM2 as essential to the development of normal hearing suggests dysregulation of cell polarity as a mechanism underlying hearing loss.
Perrault syndrome is a recessive disorder characterized by ovarian dysgenesis in females, sensorineural deafness in both males and females, and in some patients, neurological manifestations. No genes ...for Perrault syndrome have heretofore been identified. A small family of mixed European ancestry includes two sisters with well-characterized Perrault syndrome. Whole-exome sequencing of genomic DNA from one of these sisters revealed exactly one gene with two rare functional variants:
HSD17B4, which encodes 17β-hydroxysteroid dehydrogenase type 4 (HSD17B4), also known as D-bifunctional protein (DBP). HSD17B4/DBP is a multifunctional peroxisomal enzyme involved in fatty acid β-oxidation and steroid metabolism. Both sisters are compound heterozygotes for
HSD17B4 c.650A>G (p.Y217C) (maternal allele) and
HSB17B4 c.1704T>A (p.Y568X) (paternal allele). The missense mutation is predicted by structural analysis to destabilize the HSD17B4 dehydrogenase domain. The nonsense mutation leads to very low levels of
HSD17B4 transcript. Expression of mutant HSD17B4 protein in a compound heterozygote was severely reduced. Mutations in
HSD17B4 are known to cause DBP deficiency, an autosomal-recessive disorder of peroxisomal fatty acid β-oxidation that is generally fatal within the first two years of life. No females with DBP deficiency surviving past puberty have been reported, and ovarian dysgenesis has not previously been associated with this illness. Six other families with Perrault syndrome have wild-type sequences of
HSD17B4. These results indicate that Perrault syndrome and DBP deficiency overlap clinically; that Perrault syndrome is genetically heterogeneous; that DBP deficiency may be underdiagnosed; and that whole-exome sequencing can reveal critical genes in small, nonconsanguineous families.
Genes disrupted in schizophrenia may be revealed by de novo mutations in affected persons from otherwise healthy families. Furthermore, during normal brain development, genes are expressed in ...patterns specific to developmental stage and neuroanatomical structure. We identified de novo mutations in persons with schizophrenia and then mapped the responsible genes onto transcriptome profiles of normal human brain tissues from age 13 weeks gestation to adulthood. In the dorsolateral and ventrolateral prefrontal cortex during fetal development, genes harboring damaging de novo mutations in schizophrenia formed a network significantly enriched for transcriptional coexpression and protein interaction. The 50 genes in the network function in neuronal migration, synaptic transmission, signaling, transcriptional regulation, and transport. These results suggest that disruptions of fetal prefrontal cortical neurogenesis are critical to the pathophysiology of schizophrenia. These results also support the feasibility of integrating genomic and transcriptome analyses to map critical neurodevelopmental processes in time and space in the brain.
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•De novo damaging mutations are enriched in schizophrenia•Schizophrenia genes are highly coexpressed in fetal prefrontal cortex•Schizophrenia genes operate in pathways important for brain development•Disruptions of fetal prefrontal cortical neurogenesis are critical to schizophrenia
Integrating sequencing data from persons with schizophrenia and their healthy siblings with transcript data from human brain samples at different points in development reveals a network of genes coexpressed specifically in the prefrontal cortex during fetal development. The findings contextualize disease-related mutations and implicate cortical neurogenesis defects in schizophrenia.
African Americans have a disproportionate burden of aggressive young-onset breast cancer. Genomic testing for inherited predisposition to breast cancer is increasingly common in clinical practice, ...but comprehensive mutation profiles remain unknown for most minority populations. We evaluated 289 patients who self-identified as African American with primary invasive breast cancer and with personal or family cancer history or tumor characteristics associated with high genetic risk for all classes of germline mutations in known breast cancer susceptibility genes using a validated targeted capture and multiplex sequencing approach. Sixty-eight damaging germline mutations were identified in 65 (22 %, 95 % CI 18–28 %) of the 289 subjects. Proportions of patients with unequivocally damaging mutations in a breast cancer gene were 26 % (47/180; 95 % confident interval CI 20–33 %) of those with breast cancer diagnosis before age 45; 25 % (26/103; 95 % CI 17–35 %) of those with triple-negative breast cancer (TNBC); 29 % (45/156; 95 % CI 22–37 %) of those with a first or second degree relative with breast cancer before age 60 or with ovarian cancer; and 57 % (4/7; 95 % CI 18–90 %) of those with both breast and ovarian cancer. Of patients with mutations, 80 % (52/65) carried mutations in
BRCA1
and
BRCA2
genes and 20 % (13/65) carried mutations in
PALB2, CHEK2, BARD1, ATM, PTEN
, or
TP53
. The mutational allelic spectrum was highly heterogeneous, with 57 different mutations in 65 patients. Of patients meeting selection criteria other than family history (i.e., with young age at diagnosis or TNBC), 48 % (64/133) had very limited information about the history of cancer in previous generations of their families. Mutations in
BRCA1
and
BRCA2
or another breast cancer gene occur in one in four African American breast cancer patients with early onset disease, family history of breast or ovarian cancer, or TNBC. Each of these criteria defines patients who would benefit from genomic testing and novel therapies targeting DNA repair pathways.
Lynch syndrome (hereditary nonpolyposis colon cancer) and adenomatous polyposis syndromes frequently have overlapping clinical features. Current approaches for molecular genetic testing are often ...stepwise, taking a best-candidate gene approach with testing of additional genes if initial results are negative. We report a comprehensive assay called ColoSeq that detects all classes of mutations in Lynch and polyposis syndrome genes using targeted capture and massively parallel next-generation sequencing on the Illumina HiSeq2000 instrument. In blinded specimens and colon cancer cell lines with defined mutations, ColoSeq correctly identified 28/28 (100%) pathogenic mutations in MLH1 , MSH2 , MSH6 , PMS2 , EPCAM , APC , and MUTYH , including single nucleotide variants (SNVs), small insertions and deletions, and large copy number variants. There was 100% reproducibility of mutation detection between independent runs. The assay correctly identified 222 of 224 heterozygous SNVs (99.4%) in HapMap samples, demonstrating high sensitivity of calling all variants across each captured gene. Average coverage was greater than 320 reads per base pair when the maximum of 96 index samples with barcodes were pooled. In a specificity study of 19 control patients without cancer from different ethnic backgrounds, we did not find any pathogenic mutations but detected two variants of uncertain significance. ColoSeq offers a powerful, cost-effective means of genetic testing for Lynch and polyposis syndromes that eliminates the need for stepwise testing and multiple follow-up clinical visits.
Abstract Objectives Few studies have comprehensively tested all ovarian cancer patients for BRCA1 and BRCA2 ( BRCA1 / 2 ) mutations. We sought to determine if clinically identified mutation carriers ...differed in clinical characteristics and outcomes from mutation carriers not identified during routine clinical care. Methods We included women with ovarian, tubal or peritoneal carcinoma. BROCA, an assay using targeted capture and massively parallel sequencing was used to identify mutations in BRCA1 / 2 and 19 other tumor suppressor genes. We identified subjects with BRCA1 / 2 mutations using BROCA that had not previously received standard genetic testing (BROCA, n = 37) and compared them to subjects with BRCA1 / 2 mutations identified during routine clinical care (known, n = 70), and to those wildtype for 21 genes using BROCA (wildtype, n = 291). Results BROCA mutation carriers were older than known carriers, median age of 58 (range 41–77), vs. 51 (range 33-76, p = 0.003, Mann–Whitney). 58/70 (82.9%) of known carriers had a strong family history, compared with 15/37 (40.5%) of BROCA carriers, p < 0.0001, (Fisher's Exact). Median overall survival was significantly worse for BROCA mutation carriers compared to known mutation carriers, (45 vs. 93 months, p < 0.0001, HR 3.47 (1.79–6.72), Log-rank test). The improved survival for BRCA1 / 2 mutation carriers (known and BROCA) compared with wildtype cases (69 vs. 44 months, p = 0.0001, HR 0.58 (0.43–0.77), Log-rank test) was driven by known mutation carriers. Conclusions Older age, absence of a strong family history, and poor survival are all associated with decreased clinical identification of inherited BRCA1 / 2 mutations in women with ovarian cancer. Using age and family history to direct genetic testing will miss a significant percentage of mutation carriers. Testing should be initiated at the time of diagnosis to maximize identification of mutations and minimize survival bias.
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