BackgroundIn recent years, numerous studies have assessed the prevalence of germline mutations in BRCA1 and BRCA2 genes in various cohorts. We here extensively investigated the prevalence and geographical distribution of BRCA1-2 mutations in the entire genetically-homogeneous Sardinian population. The occurrence of phenotypic characteristics which may be predictive for the presence of BRCA1-2 germline mutations was also evaluated.MethodsThree hundred and forty-eight breast cancer patients presenting a familial recurrence of invasive breast or ovarian carcinoma with at least two affected family members were screened for BRCA1-2 mutations by DHPLC analysis and DNA sequencing. Association of BRCA1 and BRCA2 mutational status with clinical and pathological parameters was evaluated by Pearson's Chi-Squared test.Results and ConclusionOverall, 8 BRCA1 and 5 BRCA2 deleterious mutations were detected in 35/348 (10%) families; majority (23/35;66%) of mutations was found in BRCA2 gene. The geographical distribution of BRCA1-2 mutations was related to three specific large areas of Sardinia, reflecting its ancient history: a) the Northern area, linguistically different from the rest of the island (where a BRCA2 c.8764_8765delAG mutation with founder effect was predominant); b) the Middle area, land of the ancient Sardinian population (where BRCA2 mutations are still more common than BRCA1 mutations); and c) the South-Western area, with many Phoenician and Carthaginian locations (where BRCA1 mutations are prevalent). We also found that phenotypic features such as high tumor grading and lack of expression of estrogen/progesterone receptors together with age at diagnosis and presence of ovarian cancer in the family may be predictive for the presence of BRCA1-2 germline mutations.

The population of Sardinia is characterized by a relatively low level of genetic heterogeneity: therefore 'founder mutations' can be expected to be found. We analysed 17 probands from families with high incidence of breast cancer or breast and ovarian cancer by sequencing the full-length coding regions of BRCA1 and BRCA2 genes. A novel BRCA2 frame-shift mutation, 3951del3insAT, which produces a protein truncated at codon 1258, was observed in six patients with BC from the same village. The mutation was not found in unaffected females (matched on basis of ethnicity and age) with no family history of cancer. Haplotype analysis strongly suggests that all affected persons had a common ancestor. The identification of this clinically significant founder mutation may facilitate screening/testing for inherited risk of breast cancer.

BackgroundThe SARS-CoV-2 pandemic stimulated an outstanding global sequencing effort, which allowed to monitor viral circulation and evolution. Nuoro province (Sardinia, Italy), characterized by a relatively isolated geographical location and a low population density, was severely hit and displayed a high incidence of infection.MethodsAmplicon approach Next Generation Sequencing and subsequent variant calling in 92 respiratory samples from SARS-CoV-2 infected patients involved in infection clusters from March 2020 to May 2021.ResultsPhylogenetic analysis displayed a coherent distribution of sequences in terms of lineage and temporal evolution of pandemic. Circulating lineage/clade characterization highlighted a growing diversity over time, with an increasingly growing number of mutations and variability of spike and nucleocapsid proteins, while viral RdRp appeared to be more conserved. A total of 384 different mutations were detected, of which 196 were missense and 147 synonymous ones. Mapping mutations along the viral genome showed an irregular distribution in key genes. S gene was the most mutated gene with missense and synonymous variants frequencies of 58.8 and 23.5%, respectively. Mutation rates were similar for the S and N genes with one mutation every ∼788 nucleotides and every ∼712 nucleotides, respectively. Nsp12 gene appeared to be more conserved, with one mutation every ∼1,270 nucleotides. The frequency of variant Y144F in the spike protein deviated from global values with higher prevalence of this mutation in the island.ConclusionThe analysis of the 92 viral genome highlighted evolution over time and identified which mutations are more widespread than others. The high number of sequences also permits the identification of subclusters that are characterized by subtle differences, not only in terms of lineage, which may be used to reconstruct transmission clusters. The disclosure of viral genetic diversity and timely identification of new variants is a useful tool to guide public health intervention measures.

20118 Background: Germline alterations in the BRCA1 and BRCA2 genes highly predispose to breast and ovarian cancer. In families with BRCA1/2 mutations, identification of mutation carriers is clinically rilevant in view of the options for surveillance and prevention. The general aim of the present research is to contribute to the molecular epidemiology of BRCA1/2 genes in the italian region of Sardinia as a prerequisite for a prevention program based on DNA analysis. Methods: Fifty-two of 172 patients diagnosed with primary invasive breast carcinomas (n = 150) or ovarian cancer (n = 18) and 4 male with breast cancer referring to our departments between 2003 and 2005, had a positive family history for breast and/or ovarian cancer and were selected for BRCA1/2 mutation screening by denaturing high-performance liquid chromatography and DNA sequencing. Onehundred DNAs from healthy women originating from the same geographical area were used as population controls. Results: We identified 7 BRCA sequence alterations: 3 were already described polymorphisms while 4 novel BRCA variants were found in 11 out of 52 (21%) probands. The BRCA23951del3insAT is a novel deleterious mutation which leads to protein truncation at codon 1258 and co-occurred with the missense BRCA2S2546P in 6 probands originating from the same village and in none of the controls. Segregation analysis suggested the cis-position of the two mutations. All mutation carriers shared a common disease-associated BRCA2 haplotype indicating the presence of a founder effect. The BRCA2N272I was first observed in our population and was found in 3 unrelated probands and in none of 200 control chromosomes. The missense BRCA1E1352K mutation was present in 3 patients from two unrelated families with breast and ovarian cancer cases in three generations. Conclusions: In the present study, BRCA2 are more recurrent than BRCA1 mutations as reported for the northern part of the island. Our findings provide new epidemiological data that may be useful in defining the prevalence, mutational spectrum and penetrance of BRCA1/2 in the genetically homogeneous population of Sardinia. A comprehensive map of the BRCA mutations may facilitate screening/testing for inherited risk of breast cancer. No significant financial relationships to disclose.

The current knowledge of potential risk factors for lymphomas is limited. There is strong evidence that altered immunological function entails an increased risk of lymphoma. CTLA-4 gene encodes for a receptor that provides a negative signal to the T-cell once an immune response is initiated and complete. It is located in the 2q33 chromosomal region that harbours several genes such as CD28, ICOS, all related to immune activation playing a pivotal role in T-lymphocyte activation. Polymorphisms in these genes have been associated to a number of autoimmune diseases, including blood disorders. We have recently reported that a functional polymorphism in the CTLA-4 gene is associated with Non-Hodgkin’s lymphoma (NHL) and may have a role in genetic susceptibility to the disease. Since CD28, CTLA-4 and ICOS are closely linked and have related functions, aim of the present study was to extend the genetic analysis to the 2q33 chromosomal region harbouring these genes. Three polymorphisms of CTLA-4 gene (at positions -308C*T, +49A*G, +642 3′UTR (AT)n), the CD28 (CAA)n, ICOS c1564T*C and D2S72 markers within a 1.3cM region were analyzed in 100 unrelated NHL patients and in 128 healthy controls both originating from the central part of Sardinia. Statistical analysis was performed to test association of each marker with NHL using Chi-squared test and Odds Ratio (OR). Haplotypes were inferred and analyzed using the PHASE 2.1 software. Exact test of Linkage Disequilibrium (LD) was calculated between all pairs of seven markers separately in cases and controls using the Arlequin program. We found a strong association of the CTLA-4 +49*A and the 3′UTR (AT)82 alleles with NHL with ORs of 2 (CI95% 1.2–3.2) and 1.6 (CI95% 1.1–2.4), respectively. The −308*C−+49*A− (AT)82 was the most represented haplotype in the studied population and resulted associated with NHL (p value = 0.0029; OR = 1.7 [CI95% 1.2–2.5]). No independent association between CD28, ICOS and D2S72 markers was observed. Genetic analysis of the entire haplotype CD28–CTLA-4-D2S72-ICOS resulted in 196 and 234 different best haplotypes in patients and controls, respectively. The most common haplotype was CD28*163-308*C-+49*A-(AT)82-D2S72*156-ICOS*T and it was found to be significantly over-represented in NHLs than in controls (p value = 0.012, OR=1.86 CI95% 1.1–3). Strong LD was observed between the three CTLA-4 gene markers and the two adjacent markers CD28 and D2S72, and less significant LD was found between ICOS and some of the CTLA-4 gene markers. We found genetic linkage between a specific haplotype in the 2q33 region and NHL, but allelic association was detected for CTLA-4 markers and for none of the adjacent functionally related gene markers. Thus, it seems possible to dissect the CTLA-4 as the true “causative” risk gene for NHL susceptibility at least in Sardinian patients.The functional characterization of disease-associated CTLA4 gene variants will be worthy of future investigation to elucidate their role in the pathogenesis of NHL.