Germline Mutation in 1338 BRCA-Negative Chinese Hereditary Breast and/or Ovarian Cancer Patients: Clinical Testing with a Multigene Test Panel.

Differences in the mutation spectrum across ethnicities suggest the importance of identifying genes in addition to common high penetrant genes to estimate the associated breast cancer risk in China. A total of 1338 high-risk breast cancer patients who tested negative for germline BRCA1, BRCA2, TP53, and PTEN mutations between 2007 and 2017 were selected from the Hong Kong Hereditary Breast Cancer Family Registry. Patient samples were subjected to next-generation DNA sequencing using a multigene panel (Color Genomics). All detected pathogenic variants were validated by bidirectional DNA sequencing. The sequencing data were coanalyzed by a bioinformatics pipeline developed in-house. Sixty-one pathogenic variants (4.6%) were identified in this cohort in 11 cancer predisposition genes. Most carriers (77.1%) had early onset of breast cancer (age <45 years), 32.8% had family members with breast cancer, and 11.5% had triple-negative breast cancer. The most common mutated genes were PALB2 (1.4%), RAD51D (0.8%), and ATM (0.8%). A total of 612 variants of unknown significance were identified in 494 patients, and 87.4% of the variants of unknown significance were missense mutations. Pathogenic variants in cancer predisposition genes beyond BRCA1, BRCA2, TP53, and PTEN were detected in an additional 4.6% of patients using the multigene panel. PALB2 (1.4%) and RAD51D (0.8%) were the most commonly mutated genes in patients who tested mutation negative by a four-gene panel.

Distinct mutation spectrum, clinical outcome and therapeutic responses of typical complex/monosomy karyotype acute myeloid leukemia carrying TP53 mutations.

The present study aimed to define a subtype of complex/monosomal karyotype (CK/MK) acute myeloid leukemia (AML) by its distinct clinical features, p53 signaling and responses to p53 targeting agents. Ninety-eight young adults (range: 21-60 years; median: 49 years) with CK/MK AML were studied. They received standard induction, consolidation and allogeneic hematopoietic stem cell transplantation from siblings or matched unrelated donors if available. Chromosomal abnormalities most commonly affected chromosome 5 (30%), 7 (22%) and 17 (21%). Next generation sequencing of a 54-myeloid gene panel were available in 76 patients. Tumor protein 53 (TP53) mutations were most common (49%) and associated with the presence of -5/5q- (P < .001) and -17/17p- (P < .001), but not -7/7q- (P = .370). This "typical" CK/MK AML subtype was associated with significantly lower presenting white cell counts, higher number of karyotypic abnormalities, and inferior leukemia-free and overall survivals, compared with CK/MK AML without the typical features. Blood or bone marrow samples from typical CK/MK AML patients showed defective p53 signaling upon induction by etoposide. In vitro drug sensitivity analysis showed that they were sensitive to APR-246 that targeted mutant p53, but resistant to MDM2 antagonist MI-77301. Novel therapeutic strategies targeting TP53 mutations in CK/MK AML should be developed and tested in clinical trials.

Detection of Germline Mutation in Hereditary Breast and/or Ovarian Cancers by Next-Generation Sequencing on a Four-Gene Panel.

Mutation in BRCA1/BRCA2 genes accounts for 20% of familial breast cancers, 5% to 10% of which may be due to other less penetrant genes which are still incompletely studied. Herein, a four-gene panel was used to examine the prevalence of BRCA1, BRCA2, TP53, and PTEN in hereditary breast and ovarian cancers in Southern Chinese population. In this cohort, 948 high-risk breast and/or ovarian patients were recruited for genetic screening by next-generation sequencing (NGS). The performance of our NGS pipeline was evaluated with 80 Sanger-validated known mutations and eight negative cases. With appropriate bioinformatics analysis pipeline, the detection sensitivity of NGS is comparable with Sanger sequencing. The prevalence of BRCA1/BRCA2 germline mutations was 9.4% in our Chinese cohort, of which 48.8% of the mutations arose from hotspot mutations. With the use of a tailor-made algorithm, HomopolymerQZ, more mutations were detected compared with single mutation detection algorithm. The frequencies of PTEN and TP53 were 0.21% and 0.53%, respectively, in the Southern Chinese patients with breast and/or ovarian cancers. High-throughput NGS approach allows the incorporation of control cohort that provides an ethnicity-specific data for polymorphic variants. Our data suggest that hotspot mutations screening such as SNaPshot could be an effective preliminary screening alternative adopted in a standard clinical laboratory without NGS setup.

Germline RECQL mutations in high risk Chinese breast cancer patients.

Recently, RECQL was reported as a new breast cancer susceptibility gene. RECQL belongs to the RECQ DNA helicase family which unwinds double strand DNA and involved in the DNA replication stress response, telomere maintenance and DNA repair. RECQL deficient mice cells are prone to spontaneous chromosomal instability and aneuploidy, suggesting a tumor-suppressive role of RECQL in cancer. In this study, RECQL gene mutation screening was performed on 1110 breast cancer patients who were negative for BRCA1, BRCA2, TP53 and PTEN gene mutations and recruited from March 2007 to June 2015 in the Hong Kong Hereditary and High Risk Breast Cancer Program. Four different RECQL pathogenic mutations were identified in six of the 1110 (0.54 %) tested breast cancer patients. The identified mutations include one frame-shift deletion (c.974_977delAAGA), two splicing site mutations (c.394+1G>A, c.867+1G>T) and one nonsense mutation (c.796C>T, p.Gln266Ter). Two of the mutations (c.867+1G>T and p.Gln266Ter) were seen in more than one patients. This study provides the basis for existing of pathogenic RECQL mutations in Southern Chinese breast cancer patients. The significance of rare variants in RECQL gene in the estimation of breast cancer risk warranted further investigation in larger cohort of patients and in other ethnic groups.