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Familial colorectal cancer Type X (FCCTX) comprises a heterogeneous group of families with an increased risk of developing colorectal cancer and other related tumors, but with mismatch repair–proficient, microsatellite-stable (MSS) tumors. Unfortunately, the genetic basis underlying their cancer predisposition remains unknown. Although pathogenic germline variants in BRIP1 increase the risk of developing hereditary ovarian cancer, the involvement of BRIP1 in hereditary colorectal cancer is still not well known. In order to identify new BRIP1 variants associated with inherited colorectal cancer, affected and nonaffected individuals from 18 FCCTX or high-risk MSS colorectal cancer families were evaluated by whole-exome sequencing, and another 62 colorectal cancer patients from FCCTX or high-risk MSS colorectal cancer families were screened by a next-generation sequencing (NGS) multigene panel. The families were recruited at the Genetic Counseling Unit of Hospital Clínico San Carlos of Madrid. A total of three different BRIP1 mutations in three unrelated families were identified. Among them, there were two frameshift variants [c.1702_1703del, p.(Asn568TrpfsTer9) and c.903del, p.(Leu301PhefsTer2)] that result in the truncation of the protein and are thus classified as pathogenic (class 5). The remaining was a missense variant [c.2220G>T, p.(Gln740His)] considered a variant of uncertain significance (class 3). The segregation and loss-of-heterozygosity studies provide evidence linking the two BRIP1 frameshift variants to colorectal cancer risk, with suggestive but not definitive evidence that the third variant may be benign. The results here presented suggest that germline BRIP1 pathogenic variants could be associated with hereditary colorectal cancer predisposition. Prevention Relevance: We suggest that BRIP1 pathogenic germline variants may have a causal role in CRC as moderate cancer susceptibility alleles and be associated with hereditary CRC predisposition. A better understanding of hereditary CRC may provide important clues to disease predisposition and could contribute to molecular diagnostics, improved risk stratification, and targeted therapeutic strategies.

Introduction MUC1 overexpression has been linked to cancer development and has been associated with a higher stage at diagnosis and presence of lymph node or distant metastases. However, its prognostic significance is still unclear. We aimed to evaluate the relationship between MUC1 expression and prognosis of colorectal carcinoma. Materials and methods Immunohistochemical expression of MUC1 in 96 colorectal carcinomas with analysis of potential prognostic influence. Results 55.2% of patients were women and the mean age was 65.9 years. Tumors were more frequently located in rectum or sigmoid colon (60.4% and 21.9%). Most tumors were T3 (60.3%). 36.9% of patients showed lymph node metastases and 30.2% showed distant metastasis at the time of diagnosis. MUC1 was intensely positive in 46% and negative in 37.9% of tumors. Overall, 61% of patients recurred and 40.4% died during follow-up. 58.5% of tumors of surviving patients were intensely positive for MUC1 and 29.5% were negative, as compared with 28.5% (intense positivity) and 51.4% (negativity) in the group of patients who died (p = 0.022). 65% of tumors of patients without recurrences showed intense positivity for MUC1 and 23% of them were negative as compared with 33.9% (intense positivity) and 47% (negativity) in the group of patients who recurred (p = 0.019). Conclusions Loss of MUC1 expression was more frequent in cases with disease recurrence or death, as compared with patients with stable disease, in whom intense positivity was more frequently seen. These findings disagree with the majority of previous studies, indicating the need for further investigation.

Pathogenic sequence variants (PSV) in BRCA1 or BRCA2 (BRCA1/2) are associated with increased risk and severity of prostate cancer. We evaluated whether PSVs in BRCA1/2 were associated with risk of overall prostate cancer or high grade (Gleason 8+) prostate cancer using an international sample of 65 BRCA1 and 171 BRCA2 male PSV carriers with prostate cancer, and 3,388 BRCA1 and 2,880 BRCA2 male PSV carriers without prostate cancer. PSVs in the 3′ region of BRCA2 (c.7914+) were significantly associated with elevated risk of prostate cancer compared with reference bin c.1001-c.7913 [HR = 1.78; 95% confidence interval (CI), 1.25–2.52; P = 0.001], as well as elevated risk of Gleason 8+ prostate cancer (HR = 3.11; 95% CI, 1.63–5.95; P = 0.001). c.756-c.1000 was also associated with elevated prostate cancer risk (HR = 2.83; 95% CI, 1.71–4.68; P = 0.00004) and elevated risk of Gleason 8+ prostate cancer (HR = 4.95; 95% CI, 2.12–11.54; P = 0.0002). No genotype–phenotype associations were detected for PSVs in BRCA1. These results demonstrate that specific BRCA2 PSVs may be associated with elevated risk of developing aggressive prostate cancer. Significance: Aggressive prostate cancer risk in BRCA2 mutation carriers may vary according to the specific BRCA2 mutation inherited by the at-risk individual.

Adenomatous polyposis (AP) is classified according to cumulative adenoma number in classical AP (CAP) and attenuated AP (AAP). Genetic susceptibility is the major risk factor in CAP due to mutations in the known high predisposition genes APC and MUTYH. However, the contribution of genetic susceptibility to AAP is lower and less understood. New predisposition genes have been recently proposed, and some of them have been validated, but their scarcity hinders accurate risk estimations and prevalence calculations. AAP is a heterogeneous condition in terms of severity, clinical features and heritability. Therefore, clinicians do not have strong discriminating criteria for the recommendation of the genetic study of known predisposition genes, and the detection rate is low. Elucidation and knowledge of new AAP high predisposition genes are of great importance to offer accurate genetic counseling to the patient and family members. This review aims to update the genetic knowledge of AAP, and to expound the difficulties involved in the genetic analysis of a highly heterogeneous condition such as AAP.

The involvement of GALNT12 in colorectal carcinogenesis has been demonstrated but it is not clear to what extent it is implicated in familial CRC susceptibility. Partially inactivating variant, NM_024642.4:c.907G>A, p.(D303N), has been previously detected in familial CRC and proposed as the causative risk allele. Since phenotypes of the described carrier families showed not only CRC but also a polyp history, we hypothesized that GALNT12 could be involved in adenoma predisposition and consequently, in hereditary polyposis CRC syndromes. For that purpose, we have screened the GALNT12 gene in germline DNA from 183 unrelated attenuated polyposis patients. c.907G>A, p.(D303N) was detected in 4 cases (MAF = 1.1%) and no other candidate variants were found. After segregation studies, LOH analyses, glycosylation pattern tests and case-control studies, our results did not support the role of c.907G>A, p.(D303N) as a high-penetrance risk allele for polyposis CRC.

e17551 Background: Few studies have addressed the carcinogenic process of laryngeal cancer from its premalignant phases. Our aim was to compare mutational status of laryngeal dysplasias (LD) evolving to laryngeal cancer (ELC) and not evolving to LC (NELC). Methods: Retrospective study of LD diagnosed between 2007 and 2011. A customized 15-gene NGS panel (DICER, IRF6, NOTCH1, NOTCH2, NOTCH3, NOTCH2NLA, PIK3CA, PTEN, RB1, RIPK4, SYNE1, SYNE2, TP53, TP63, CASP8) was used for mutational analysis with Truseq Custom Amplicon (Illumina) performed in FFPE LD samples and results compared between LD-ELC and LD-NELC. Results: Sixty-four patients (pts) with LD were identified. LD-ELC (N = 23) and LD-NELC (N = 41) were scored as mild (N = 40; NELC: 32 / ELC:8), moderate (N = 8; NELC: 4/ ELC: 4) and severe (N = 16; NELC:5 / ELC: 11). Prior or current moderate-to-heavy tobacco smoking ( > 10 pack-year): 53/64 (83%). Males: N = 50 (ELC: 21; NELC: 29); Female: N = 14 (ELC: 2; NELC: 12). Median time to cancer among 23 LD-ELC: 8 m (range: 0-46). Forty-seven gene variants were detected in ELC not found in NELC, of which 27 were pathogenic/likely pathogenic: Frameshift: 8 (1 in NOTCH2, 1 in PTEN, 2 in RB1, 2 in SYNE1 y 2 in SYNE2); Stop-gained: 3 (1 in NOTCH2NL, 2 in SYNE2); Splicing: 3 (1 in RB1, 1 in RIPK4 y 1 in TP53); Missense: 12 (1 in IRF6, 2 in NOTCH1, 1 in RB1, 2 in RIPK4, 6 in SYNE1). Conclusions: LD from pts ELC showed a different mutational profile than LD-NELC. These results show promise for identifying pts at higher risk for developing LC and should be validated in a larger, prospective study.