Gene Signature Associated with Nervous System in an Experimental Radiation- and Estrogen-Induced Breast Cancer Model

Breast cancer is frequently the most diagnosed female cancer in the world. The experimental studies on cancer seldom focus on the relationship between the central nervous system and cancer. Despite extensive research into the treatment of breast cancer, chemotherapy resistance is an important issue limiting the efficacy of treatment. Novel biomarkers to predict prognosis or sensitivity to chemotherapy are urgently needed. This study examined nervous-system-related genes. The profiling of differentially expressed genes indicated that high-LET radiation, such as that emitted by radon progeny, in the presence of estrogen, induced a cascade of events indicative of tumorigenicity in human breast epithelial cells. Bioinformatic tools allowed us to analyze the genes involved in breast cancer and associated with the nervous system. The results indicated that the gene expression of the Ephrin A1 gene (EFNA1), the roundabout guidance receptor 1 (ROBO1), and the kallikrein-related peptidase 6 (KLK6) was greater in T2 and A5 than in the A3 cell line; the LIM domain kinase 2 gene (LIMK2) was greater in T2 than A3 and A5; the kallikrein-related peptidase 7 (KLK7), the neuroligin 4 X-linked gene (NLGN4X), and myelin basic protein (MBP) were greater than A3 only in T2; and the neural precursor cell expressed, developmentally down-regulated 9 gene (NEDD9) was greater in A5 than in the A3 and E cell lines. Concerning the correlation, it was found a positive correlation between ESR1 and EFNA1 in BRCA-LumA patients; with ROBO1 in BRCA-Basal patients, but this correlation was negative with the kallikrein-related peptidase 6 (KLK6) in BRCA-LumA and -LumB, as well as with LIMK2 and ROBO1 in all BRCA. It was also positive with neuroligin 4 X-linked (NLGN4X) in BRCA-Her2 and BRCA-LumB, and with MBP in BRCA-LumA and -LumB, but negative with KLK7 in all BRCA and BRCA-LumA and NEDD9 in BRCA-Her2. The differential gene expression levels between the tumor and adjacent tissue indicated that the ROBO1, KLK6, LIMK2, KLK7, NLGN4X, MBP, and NEDD9 gene expression levels were higher in normal tissues than in tumors; however, EFNA1 was higher in the tumor than the normal ones. EFNA1, LIMK2, ROBO1, KLK6, KLK7, and MBP gene expression had a negative ER status, whereas NEDD9 and NLGN4X were not significant concerning ER status. In conclusion, important markers have been analyzed concerning genes related to the nervous system, opening up a new avenue of studies in breast cancer therapy.

Association of Germline Variation in Driver Genes with Breast Cancer Risk in Chilean Population

Cancer is a genomic disease, with driver mutations contributing to tumorigenesis. These potentially heritable variants influence risk and underlie familial breast cancer (BC). This study evaluated associations between BC risk and 13 SNPs in driver genes MAP3K1, SF3B1, SMAD4, ARID2, ATR, KMT2C, MAP3K13, NCOR1, and TBX3, in BRCA1/2-negative Chilean families. SNPs were genotyped using TaqMan Assay in 492 cases and 1285 controls. There were no associations between rs75704921:C>T (ARID2); rs2229032:A>C (ATR); rs3735156:C>G (KMT2C); rs2276738:G>C, rs2293906:C>T, rs4075943T:>A, rs13091808:C>T (MAP3K13); rs178831:G>A (NCOR1); or rs3759173:C>A (TBX3) and risk. The MAP3K1 rs832583 A allele (C/A+A/A) showed a protective effect in families with moderate BC history (OR = 0.7 [95% CI 0.5-0.9] p = 0.01). SF3B1 rs16865677-T (G/T+T/T) increased risk in sporadic early-onset BC (OR = 1.4 [95% CI 1.0-2.0] p = 0.01). SMAD4 rs3819122-C (A/C+C/C) increased risk in cases with moderate family history (OR = 2.0 [95% CI 1.3-2.9] p ≤ 0.0001) and sporadic cases diagnosed ≤50 years (OR = 1.6 [95% CI 1.1-2.2] p = 0.006). SMAD4 rs12456284:A>G increased BC risk in G-allele carriers (A/G + G/G) in cases with ≥2 BC/OC cases and early-onset cases (OR = 1.2 [95% CI 1.0-1.6] p = 0.04 and OR = 1.4 [95% CI 1.0-1.9] p = 0.03, respectively). Our study suggests that specific germline variants in driver genes MAP3K1, SF3B1, and SMAD4 contribute to BC risk in Chilean population.

Interaction and integration among behaviors of adult Drosophila in nature

Living in environments whose ecologies vary in periods as short as 24 h is a challenge for animals as Drosophila species that inhabit pear and apple orchards. These orchards have sunny and shady sections. The size and shape of these habitats change daily according to the position of the sun in the sky. Sunny areas are related to dryness and water loss, and shady places have lower temperatures and higher humidity. The presence of heterospecific flies may lead to competition for space and food. In sunny habitats we did not find adult Drosophila. In shady sections we found conspecific groups D. melanogaster, D. simulans, D. immigrans, D. subobscura, and the Chilean endemic D. pavani perched on grasses and herbs at 8-10 cm from fruits that had fallen on the ground. In the fruits, 99% of the adults were females and they were not grouped. The way in which daily changes in the size and shape of shady habitats together with the presence of heterospecific adults influence the selection of places to live is poorly understood in Drosophila. Our experiments show that adults of the five species prefer dark areas. The experimental results show that the odors of each species: i) influence conspecifics to select similar perch sites and decrease mobility, and ii) increase mobility in heterospecific adults and modify their perch site preferences. Attractions between conspecifics, the repulsions between species, and preferences for shaded areas matter in choosing a place to live in the five Drosophila species. These behaviors seem to have evolved as coordinated routines, contributing to the coexistence of the five Drosophila species in the apple and pear orchards examined.

The Product of the Fission Yeast fhl1 Gene Binds to the HomolE Box and Activates In Vitro Transcription of Ribosomal Protein Genes

Fission yeast ribosomal protein genes (RPGs) contain a HomolD box as a core promoter element required for transcription. Some of the RPGs also contain a consensus sequence named HomolE, located upstream of the HomolD box. The HomolE box acts as an upstream activating sequence (UAS), and it is able to activate transcription in RPG promoters containing a HomolD box. In this work, we identified a HomolE-binding protein (HEBP) as a polypeptide of 100 kDa, which was able to bind to the HomolE box in a Southwestern blot assay. The features of this polypeptide were similar to the product of the fhl1 gene of fission yeast. The Fhl1 protein is the homolog of the FHL1 protein of budding yeast and possesses fork-head-associated (FHA) and fork-head (FH) domains. The product of the fhl1 gene was expressed and purified from bacteria, and it was demonstrated that is able to bind the HomolE box in an electrophoretic mobility assay (EMSA), as well as being able to activate in vitro transcription from an RPG gene promoter containing HomolE boxes upstream of the HomolD box. These results indicate that the product of the fhl1 gene of fission yeast can bind to the HomolE box, and it activates the transcription of RPGs.

A Single Variant in Pri-miRNA-155 Associated with Susceptibility to Hereditary Breast Cancer Promotes Aggressiveness in Breast Cancer Cells

Variants in genes encoding for microRNAs have been associated with their deregulation in breast cancer (BC). Sequencing of microRNAs deregulated in BC was performed using DNA from Chilean patients with a strong family history and negative for mutations in BRCA1/BRCA2. Seventeen variants were identified, three of which were selected for a case-control association study: rs376491654 (miR-335), rs755634302 (miR-497), and rs190708267 (miR-155). For rs190708267 C>T, the heterozygous T allele was detected in four BC cases and absent in controls, while homozygous TT cases were not detected. Variants were modelled in silico, cloned in a plasmid, expressed in BC cell lines, and functional in vitro assays were performed. Overexpression of the miR-155-T allele increased mature miR-155-5p levels in both BC cell lines, suggesting that its presence alters pre-miR-155 processing. Moreover, BC cells overexpressing the miR-155-T allele showed increased proliferation, migration, and resistance to cisplatin-induced death compared to miR-155-C overexpressing cells. Of note, the 3′UTR of APC, GSK3β, and PPP1CA genes, all into the canonical Wnt signaling pathway, were identified as direct targets. APC and GSK3β mRNA levels decreased while PP1 levels increased. These results suggest a pathogenic role of the variant rs190708267 (miR-155) in BRCA 1/2 negative BC, conferring susceptibility and promoting traits of aggressiveness.

Genetic Profile of Patients with Limb-Girdle Muscle Weakness in the Chilean Population

Hereditary myopathies are a group of genetically determined muscle disorders comprising more than 300 entities. In Chile, there are no specific registries of the distinct forms of these myopathies. We now report the genetic findings of a series of Chilean patients presenting with limb-girdle muscle weakness of unknown etiology. Eighty-two patients were explored using high-throughput sequencing approaches with neuromuscular gene panels, establishing a definite genetic diagnosis in 49 patients (59.8%) and a highly probable genetic diagnosis in eight additional cases (9.8%). The most frequent causative genes identified were DYSF and CAPN3, accounting for 22% and 8.5% of the cases, respectively, followed by DMD (4.9%) and RYR1 (4.9%). The remaining 17 causative genes were present in one or two cases only. Twelve novel variants were identified. Five patients (6.1%) carried a variant of uncertain significance in genes partially matching the clinical phenotype. Twenty patients (24.4%) did not carry a pathogenic or likely pathogenic variant in the phenotypically related genes, including five patients (6.1%) presenting an autoimmune neuromuscular disorder. The relative frequency of the different forms of myopathy in Chile is like that of other series reported from different regions of the world with perhaps a relatively higher incidence of dysferlinopathy.

Heritable genomic diversity in breast cancer driver genes and associations with risk in a Chilean population

BACKGROUND

Driver mutations are the genetic components responsible for tumor initiation and progression. These variants, which may be inherited, influence cancer risk and therefore underlie many familial cancers. The present study examines the potential association between SNPs in driver genes SF3B1 (rs4685), TBX3 (rs12366395, rs8853, and rs1061651) and MAP3K1 (rs72758040) and BC in BRCA1/2-negative Chilean families.

METHODS

The SNPs were genotyped in 486 BC cases and 1258 controls by TaqMan Assay.

RESULTS

Our data do not support an association between rs4685:C > T, rs8853:T > C, or rs1061651:T > C and BC risk. However, the rs12366395-G allele (A/G + G/G) was associated with risk in families with a strong history of BC (OR = 1.2 [95% CI 1.0-1.6] p = 0.02 and OR = 1.5 [95% CI 1.0-2.2] p = 0.02, respectively). Moreover, rs72758040-C was associated with increased risk in cases with a moderate-to-strong family history of BC (OR = 1.3 [95% CI 1.0-1.7] p = 0.02 and OR = 1.3 [95% CI 1.0-1.8] p = 0.03 respectively). Finally, risk was significantly higher in homozygous C/C cases from families with a moderate-to-strong BC history (OR = 1.8 [95% CI 1.0-3.1] p = 0.03 and OR = 1.9 [95% CI 1.1-3.4] p = 0.01, respectively). We also evaluated the combined impact of rs12366395-G and rs72758040-C. Familial BC risk increased in a dose-dependent manner with risk allele count, reflecting an additive effect (p-trend = 0.0002).

CONCLUSIONS

Our study suggests that germline variants in driver genes TBX3 (rs12366395) and MAP3K1 (rs72758040) may influence BC risk in BRCA1/2-negative Chilean families. Moreover, the presence of rs12366395-G and rs72758040-C could increase BC risk in a Chilean population.

Genetic Variation in MicroRNA-423 Promotes Proliferation, Migration, Invasion, and Chemoresistance in Breast Cancer Cells

MicroRNA-423 (miR-423) is highly expressed in breast cancer (BC). Previously, our group showed that the SNP rs6505162:C>A located in the pre-miR-423 was significantly associated with increased familial BC risk in patients with a strong family history of BC. Therefore, in this study, we evaluated the functional role of rs6505162 in mammary tumorigenesis in vitro to corroborate the association of this SNP with BC risk. We found that rs6505162:C>A upregulated expression of both mature miR-423 sequences (3p and 5p). Moreover, pre-miR-423-A enhanced proliferation, and promoted cisplatin resistance in BC cell lines. We also showed that pre-miR-423-A expression decreased cisplatin-induced apoptosis, and increased BC cell migration and invasion. We propose that the rs6505162-A allele promotes miR-423 overexpression, and that the rs6505162-A allele induces BC cell proliferation, viability, chemoresistance, migration, and invasion, and decreases cell apoptosis as a consequence. We suggest that rs6505162:C>A is a functional SNP site with potential utility as a marker for early diagnosis, prognosis, and treatment efficacy monitoring in BRCA1/2-negative BC patients, as well as a possible therapeutic target.

Association between single-nucleotide polymorphisms in miRNA and breast cancer risk: an updated review

Breast cancer (BC), a heterogeneous, aggressive illness with high mortality, is essentially a genomic disease. While the high-penetrance genes BRCA1 and BRCA2 play important roles in tumorigenesis, moderate- and low-penetrance genes are also involved. Single-nucleotide polymorphisms (SNPs) in microRNA (miRNA) genes have recently been identified as BC risk factors. miRNA genes are currently classified as low-penetrance. SNPs are the most common variations in the human genome. While the role of miRNA SNPs in BC susceptibility has been studied extensively, results have been inconsistent. This review analyzes the results of association studies between miRNA SNPs and BC risk from countries around the world. We conclude that: (a) By continent, the largest proportion of studies to date were conducted in Asia (65.0 %) and the smallest proportion in Africa (1.8 %); (b) Association studies have been completed for 67 different SNPs; (c) 146a, 196a2, 499, 27a, and 423 are the most-studied miRNAs; (d) The SNPs rs2910164 (miRNA-146a), rs11614913 (miRNA-196a2), rs3746444 (miRNA-499) and rs6505162 (miRNA-423) were the most widely associated with increased BC risk; (e) The majority of studies had small samples, which may affect the precision and power of the results; and (f) The effect of an SNP on BC risk depends on the ethnicity of the population. This review also discusses potential explanations for controversial findings.

NOD1 rs2075820 (p.E266K) polymorphism is associated with gastric cancer among individuals infected with cagPAI-positive H. pylori

Background

Helicobacter pylori is detected by pathogen recognition receptors including toll-like receptors (TLR) and nucleotide-binding oligomerization domain (NOD)-like receptors, eliciting an innate immune response against this bacteria. The aim of this study was to assess if polymorphisms of TLR2, TLR4, TLR5, NOD1 and NOD2 genes are associated with gastric cancer, in particular in individuals infected with H. pylori.

Results

A case-control study of 297 gastric cancer patients and 300 controls was performed to assess the association of 17 polymorphisms. Analyses performed under the allele model did not find association with gastric cancer. However, NOD1 rs2075820 (p.E266K) showed association with intestinal-type gastric cancer among H. pylori infected subjects (OR = 2.69, 95% CI 1.41–5.13, p = 0.0026). The association was not statistically significant in diffuse-type gastric cancer cases (OR = 1.26, 95% CI 0.63–2.52, p = 0.51). When the analyses were performed in patients carrying H. pylori strains harboring the cag pathogenicity island (cagPAI), we noticed significant association with NOD1 rs2075820 (OR = 4.90, 95% CI 1.80–3.36, p = 0.0019), in particular for intestinal-type gastric cancer cases (OR = 7.16, 95% CI 2.40–21.33, p = 4.1 × 10^− 4) but not among diffuse-type gastric cancer cases (OR = 3.39, 95% CI 1.13–0.10, p = 0.03).

Conclusions

NOD1 rs2075820 increases the risk of intestinal-type gastric cancer among individuals infected with H. pylori, particularly in those harboring the cagPAI.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40659-021-00336-4.

Phosphorylation of Endothelin-Converting Enzyme-1c at Serines 18 and 20 by CK2 Promotes Aggressiveness Traits in Colorectal Cancer Cells

Endothelin-converting enzyme-1 (ECE1) activates the endothelin-1 peptide, which upregulates pathways that are related to diverse hallmarks of cancer. ECE1 is expressed as four isoforms differing in their N-terminal domains. Protein kinase CK2 phosphorylates the N-terminus of isoform ECE1c, enhancing its stability and promoting invasiveness of colorectal cancer cells. However, the specific residues in ECE1c that are phosphorylated by CK2 and how this phosphorylation promotes invasiveness was unknown. Here we demonstrate that Ser-18 and Ser-20 are the bona fide residues phosphorylated by CK2 in ECE1c. Thus, biphospho-mimetic ECE1c^DD and biphospho-resistant ECE1c^AA mutants were constructed and stably expressed in different colorectal cancer cells through lentiviral transduction. Biphospho-mimetic ECE1c^DD displayed the highest stability in cells, even in the presence of the specific CK2 inhibitor silmitasertib. Concordantly, ECE1c^DD-expressing cells showed enhanced hallmarks of cancer, such as proliferation, migration, invasiveness, and self-renewal capacities. Conversely, cells expressing the less-stable biphospho-resistant ECE1c^AA showed a reduction in these features, but also displayed an important sensitization to 5-fluorouracil, an antineoplastic agent traditionally used as therapy in colorectal cancer patients. Altogether, these findings suggest that phosphorylation of ECE1c at Ser-18 and Ser-20 by CK2 promotes aggressiveness in colorectal cancer cells. Therefore, phospho-ECE1c may constitute a novel biomarker of poor prognosis and CK2 inhibition may be envisioned as a potential therapy for colorectal cancer patients.

The Genetic Population Structure of Robinson Crusoe Island, Chile

Studies examining genetic conditions common in Latin America are highly underrepresented in the scientific literature. Understanding of the population structure is limited, particularly Chile, in part due to the lack of available population specific data. An important first-step in elucidating disease mechanisms in Latin America countries is to understand the genetic structure of isolated populations. Robinson Crusoe Island (RCI) is a small land mass off the coast of Chile. The current population of over 900 inhabitants are primarily descended from a small number of founders who colonized the island in the late 1800s. Extensive genealogical records can trace the ancestry of almost the entire population. We perform a comprehensive genetic analysis to investigate the ancestry of the island population, examining ancestral mitochondrial and Y chromosome haplogroups, as well as autosomal admixture. Mitochondrial and Y chromosome haplogroups indicated a substantial European genetic contribution to the current RCI population. Analysis of the mitochondrial haplogroups found in the present-day population revealed that 79.1% of islanders carried European haplogroups, compared to 60.0% of the mainland Chilean controls from Santiago. Both groups showed a substantially lower contribution of indigenous haplogroups than expected. Analysis of the Y chromosome haplogroups also showed predominantly European haplogroups detected in 92.3% of male islanders and 86.7% of mainland Chilean controls. Using the near-complete genealogical data collected from the RCI population, we successfully inferred the ancestral haplogroups of 16/23 founder individuals, revealing genetic ancestry from Northern and Southern Europe. As mitochondrial and Y investigations only provide information for direct maternal and paternal lineages, we expanded this to investigate genetic admixture using the autosomes. Admixture analysis identified substantial indigenous genetic admixture in the RCI population (46.9%), higher than that found in the Santiago mainland Chilean controls (43.4%), but lower than a more representative Chilean population (Chile_GRU) (49.1%). Our study revealed the Robinson Crusoe Island population show a substantial genetic contribution for indigenous Chileans, similar to the level reported in mainland Chileans. However, direct maternal and paternal haplogroup analysis revealed strong European genetic contributions consistent with the history of the Island.

Endothelin-converting enzyme-1c promotes stem cell traits and aggressiveness in colorectal cancer cells

Endothelin-1 is a mitogenic peptide that activates several proliferation, survival, and invasiveness pathways. The effects of endothelin-1 rely on its activation by endothelin-converting enzyme-1 (ECE1), which is expressed as four isoforms with different cytoplasmic N termini. Recently, isoform ECE1c has been suggested to have a role in cancer aggressiveness. The N terminus of ECE1c is phosphorylated by protein kinase CK2 (also known as casein kinase 2), and this enhances its stability and promotes invasiveness in colorectal cancer cells. However, it is not known how phosphorylation improves stability and why this is correlated with increased aggressiveness. We hypothesized that CK2 phosphorylation protects ECE1c from N-terminal ubiquitination and, consequently, from proteasomal degradation. Here, we show that lysine 6 is the bona fide residue involved in ubiquitination of ECE1c and its mutation to arginine (ECE1c^K6R ) significantly impairs proteasomal degradation, thereby augmenting ECE1c stability, even in the presence of the CK2 inhibitor silmitasertib. Furthermore, colorectal cancer cells overexpressing ECE1c^K6R displayed enhanced cancer stem cell (CSC) traits, including increased stemness gene expression, chemoresistance, self-renewal, and colony formation and spheroid formation in vitro, as well as enhanced tumor growth and metastasis in vivo. These findings suggest that CK2-dependent phosphorylation enhances ECE1c stability, promoting an increase in CSC-like traits. Therefore, phospho-ECE1c may be a biomarker of poor prognosis and a potential therapeutic target for colorectal cancer.

Diversity of clinical, radiographic and genealogical findings in 41 families with amelogenesis imperfecta

Amelogenesis imperfecta (AI) is a group of enamel development disorders that alter the structure and chemical composition of the tissue. There is great variability in the clinical presentation; according to Witkop, AI can be categorized into 14 subtypes, which makes its diagnosis extremely complex.

OBJECTIVE

This study aimed to describe and determine the frequency of clinical and radiographic features and inheritance patterns found in 41 Chilean families diagnosed with diverse types of AI.

MATERIAL AND METHODS

We analyzed the clinical records, photographs, pedigrees and radiographs of 121 individuals recruited between 2003 and 2016. All of the information was included in a database that was analyzed using the application Stata 14.

RESULTS

The 72 affected individuals had average age of 16 years, and no sex association with the presence of AI was found. The most frequent clinical subtypes were as follows: 43% hypomature, 25% hypoplastic, 21% hypomature/hypoplastic, 7% hypocalcified and 4% hypocalcified/hypoplastic. The number of severely affected teeth was 22, which occurred in the patients with hypocalcified and hypocalcified/hypoplasic AI who presented the highest number of damaged teeth. Caries and periodontal disease were found in 47 and 32% of the patients, respectively. Malocclusions were observed in 43% of the individuals with AI, with open bite being the most frequent. Radiographically, the thickness of the enamel decreased in 51% of the patients, and 80% showed decreased radiopacity of the enamel compared to that of dentin. Autosomal dominant inheritance pattern was found in 37% of the families with hypoplastic AI, and autosomal recessive pattern was present in 56% of the other clinical subtypes, but more frequently in those affected with hypomature and hypocalcified AI.

CONCLUSION

Of the five clinical subtypes, autosomal recessive hypomature, autosomal dominant hypoplastic and autosomal recessive hypomature/hypoplastic AI were the most prevalent subtypes in this group.

Prevalence of clarithromycin resistance in Helicobacter pylori in Santiago, Chile, estimated by real-time PCR directly from gastric mucosa

BACKGROUND

Current available treatments for Helicobacter pylori eradication are chosen according to local clarithromycin and metronidazole resistance prevalence. The aim of this study was to estimate, by means of molecular methods, both clarithromycin and metronidazole resistance in gastric mucosa from patients infected with H.pylori.

METHODS

A total of 191 DNA samples were analyzed. DNA was purified from gastric mucosa obtained from patients who underwent an upper gastrointestinal endoscopy at an university hospital from Santiago, Chile, between 2011 and 2014. H.pylori was detected by real-time PCR. A 5'exonuclease assay was developed to detect A2142G and A2143G mutations among H.pylori-positive samples. rdxA gene was sequenced in samples harboring A2142G and A2143G mutations in order to detect mutations that potentially confer dual clarithromycin and metronidazole resistance.

RESULTS

Ninety-three (93) out of 191 DNA samples obtained from gastric mucosa were H.pylori-positive (48.7%). Clarithromycin-resistance was detected in 29 samples (31.2% [95%CI 22.0-41.6%]). The sequencing of rdxA gene revealed that two samples harbored truncating mutations in rdxA, one sample had an in-frame deletion, and 11 had amino acid changes that likely cause metronidazole resistance.

CONCLUSIONS

We estimated a prevalence of clarithomycin-resistance of 31.8% in Santiago, Chile. Three of them harbor inactivating mutations in rdxA and 11 had missense mutations likely conferring metronidazole resistance. Our results require further confirmation. Nevertheless, they are significant as an initial approximation in re-evaluating the guidelines for H.pylori eradication currently used in Chile.

No Evidence for Linkage and Association between 4q Microsatellite Markers and Nonsyndromic Cleft Lip and Palate in Chilean Case-Parents Trios

Objective

Nonsyndromic cleft lip/palate (NSCLP) has the characteristics of a complex genetic trait. Linkage and association studies have suggested that one or more clefting loci may be located on chromosome 4q. The goal of this study was to evaluate the possible linkage and association due to linkage disequilibrium between five microsatellite markers located on 4q28 to 4q33 and NSCLP, using the case-parent trio design.

Subjects and Methods

A total of 56 Chilean families (32 simplex and 24 multiplex) were recruited. Microsatellite markers were analyzed using polymerase chain reaction with fluorescent-labeled forward primers, followed by electrophoresis on a laser-fluorescent sequencer. Case-parents trios were ascertained to assess linkage and linkage disequilibrium through a multistage procedure. Transmission disequilibrium tests for multiple alleles were carried out to assess the statistical significance of 4q28 to 4q33 microsatellite markers.

Results

Only weak evidence for linkage was obtained for the FGA marker (asymptotic uncorrected p value = .08 and empirical p value = .05). Only the FGA and UCP1 markers were selected for association analysis in trios, with unrelated cases achieving a nearly significant result for the UCP1 marker (asymptotic uncorrected p value = .07 and empirical p value = .19).

Conclusion

Though the FGA and UCP1 markers showed nearly significant p values for linkage and association, respectively, the results of the present study provided insufficient evidence of the existence of a major susceptibility locus in the 4q region that was analyzed in the present study.

Association between 10 Microsatellite Markers and Nonsyndromic Cleft Lip Palate in the Chilean Population

Objective

The objective of this case-control study was to evaluate the possible association between nonsyndromic cleft lip/palate (NSCLP) and 10 genetic markers in four chromosomal regions in the admixed Spanish-Amerindian Chilean population.

Setting

Study participants included 56 patients with NSCLP identified and interviewed for positive family history during the course of clinical examinations at different rehabilitation centers in the cities of Santiago and Talca, Chile. A control group of 59 normal individuals without known familial antecedents of clefting was obtained from blood bank donors of the University Hospital, University of Chile. Cases and controls belonged to low- to low-middle socioeconomic strata.

Results

Ten markers from chromosome 4p, 4q, 6p, 17q, and 19q were assessed (MSX1, D4S175, D4S192, F13A1, EDN1, D6S89, D6S105, D6S109, D17S579, BCL3). Four of them showed significant deviations from Hardy-Weinberg expectations in controls, according to the exact test (D4S192, BCL3, F13A1, and D6S89). The case-control comparison by means of the CLUMP program showed significant differences only in BCL3, and D6S109 almost reached statistical significance.

Conclusions

Most of the genetic regions with positive results in Caucasian populations may not be involved in NSCLP in Chile, regardless of the positive evidence for the candidate region on chromosome 19. Similar findings have been reported recently in the Chinese population.

The genetics and development of mandibles and hypopharyngeal sclerite and cornua in larvae of Drosophila gaucha

The genetics and epigenetic processes associated with morphological organization are a principal aim of biology, ranging from cohesion between cells to shape and size of organisms. We investigate the post-embryonic development of Hypopharyngeal sclerite and cornua HPC and mandibles M of Drosophila gaucha larva. Integrated functioning of these Cephalopharyngeal skeleton parts of D. gaucha larva is essential for food acquisition, participating in locomotion and microhabitat selection. We examined two isolates by recording the growth of the HPC and M every 24 h for 8 days in parental, F₁, F₂ and backcross larvae. In F₁ larvae, the HPC and M growth was similar to the parental. In F₂ and backcross larvae, the growth was slower. Epistasis and dominance are the principal sources upon which the growth of HPC and M are based. Pleiotropic genes seem also to be involved in integrating the development of M and HPC. Our data suggest that hybridization of the isolates modified epigenetic processes involved in the development of those morphological structures of D. gaucha larva.

Mutations in BRCA1, BRCA2 and other breast and ovarian cancer susceptibility genes in Central and South American populations

Breast cancer (BC) is the most common malignancy among women worldwide. A major advance in the understanding of the genetic etiology of BC was the discovery of BRCA1 and BRCA2 (BRCA1/2) genes, which are considered high-penetrance BC genes. In non-carriers of BRCA1/2 mutations, disease susceptibility may be explained of a small number of mutations in BRCA1/2 and a much higher proportion of mutations in ethnicity-specific moderate- and/or low-penetrance genes. In Central and South American populations, studied have focused on analyzing the distribution and prevalence of BRCA1/2 mutations and other susceptibility genes that are scarce in Latin America as compared to North America, Europe, Australia, and Israel. Thus, the aim of this review is to present the current state of knowledge regarding pathogenic BRCA variants and other BC susceptibility genes. We conducted a comprehensive review of 47 studies from 12 countries in Central and South America published between 2002 and 2017 reporting the prevalence and/or spectrum of mutations and pathogenic variants in BRCA1/2 and other BC susceptibility genes. The studies on BRCA1/2 mutations screened a total of 5956 individuals, and studies on susceptibility genes analyzed a combined sample size of 11,578 individuals. To date, a total of 190 different BRCA1/2 pathogenic mutations in Central and South American populations have been reported in the literature. Pathogenic mutations or variants that increase BC risk have been reported in the following genes or genomic regions: ATM, BARD1, CHECK2, FGFR2, GSTM1, MAP3K1, MTHFR, PALB2, RAD51, TOX3, TP53, XRCC1, and 2q35.

Linkage Disequilibrium between MSX1 and Non-syndromic Cleft Lip/Palate in the Chilean Population

Non-syndromic cleft lip/palate (NSCLP) is a complex genetic trait. Linkage and association studies have suggested that a clefting locus could be located on chromosome 4p. Sixty Chilean families were recruited for this study; from these, we used unrelated trios to evaluate the possible linkage disequilibrium between MSX1 and NSCLP. An intragenic marker, MSX1-CA, and an extragenic marker, D4S432 at a distance of 0.8 cM from MSX1, were analyzed by means of polymerase chain-reaction with fluorescent-labeled forward primers, followed by electrophoresis on a laser-fluorescent sequencer. We carried out a transmission/disequilibrium test (TDT) for multiple alleles to evaluate the presence of linkage disequilibrium. Results showed a preferential transmission of the 169-bp allele of MSX1 (p = 0.03). Although there was no preferential transmission for the D4S432 marker, the overall extended TDT (ETDT) showed a significant result (p = 0.01). The authors’ findings support the hypothesis of the contribution of MSX1 in the etiology of NSCLP in the Chilean population.

Association of single nucleotide polymorphisms in Pre-miR-27a, Pre-miR-196a2, Pre-miR-423, miR-608 and Pre-miR-618 with breast cancer susceptibility in a South American population

Background

MicroRNAs (miRNAs) are a novel class of endogenous, non-coding, single-stranded RNAs capable of regulating gene expression by suppressing translation or degrading mRNAs. Single nucleotide polymorphisms (SNP) can alter miRNA expression, resulting in diverse functional consequences. Previous studies have examined the association of miRNA SNPs with breast cancer (BC) susceptibility. The contribution of miRNA gene variants to BC susceptibility in South American women had been unexplored. Our study evaluated the association of the SNPs rs895819 in pre-miR27a, rs11614913 in pre-miR-196a2, rs6505162 in pre-miR-423, rs4919510 in miR-608, and rs2682818 in pre-mir-618 with familial BC and early-onset non-familial BC in non-carriers of BRCA1/2 mutations from a South American population.

Results

We evaluated the association of five SNPs with BC risk in 440 cases and 807 controls. Our data do not support an association of rs11614913:C > T and rs4919510:C > G with BC risk. The rs6505162:C > A was significantly associated with increased risk of familial BC in persons with a strong family history of BC (OR = 1.7 [95 % CI 1.0–2.0] p = 0.05). The rs2682818:C > A genotype C/A is associated with an increased BC risk in non-familial early-onset BC. For the rs895819:A > G polymorphism, the genotype G/G is significantly associated with reduced BC risk in families with a moderate history of BC (OR = 0.3 [95 % CI 0.1–0.8] p = 0.01).

Conclusions

The contribution of variant miRNA genes to BC in South American women had been unexplored. Our findings support the following conclusions: a) rs6505162:C > A in pre-miR-423 increases risk of familial BC in families with a strong history of BC; b) the C/A genotype at rs2682818:C > A (pre-miR-618) increases BC risk in non-familial early-onset BC; and c) the G/G genotype at rs895819:A > G (miR-27a) reduces BC risk in families with a moderate history of BC.

Association of PALB2 sequence variants with the risk of familial and early-onset breast cancer in a South-American population

Background

Germline mutations in PALB2 have been identified in approximately 1% of familial breast cancer (BC) in several populations. Nevertheless its contribution in the South-American population is unknown. The goal of this study was to determine the prevalence of PALB2 mutations in the Chilean population.

Methods

100 Chilean BRCA1/2-negatives familial BC cases were included for the PALB2 mutation analysis. We use conformational sensitive gel electrophoresis and direct sequencing. Using a case-control design, we studied the identified variants in 436 BC cases and 809 controls to evaluate their possible association with BC risk.

Results

No pathogenic mutations were detected. We identified three variants, the variant c.1861C > A not previously described was found in one of the 436 cases and none of the 809 controls. The bioinformatic analyses indicate that this variant probably is not pathogenic. PALB2 c.1676A > G (rs152451A/G) and c.2993C > T (rs45551636C/T) variants were significantly associated with increased BC risk only in cases with a strong family history of BC (OR = 1.9 [CI 95% 1.3-2.8] p < 0.01 and OR = 3.3 [CI 95% 1.4-7.3] p < 0.01, respectively). The rs152451A/G-rs45551636C/T composite genotype produce increase of the BC risk in cases with a strong family history of BC (OR = 3.6 [CI 95% 1.7-8.0] p = 0.003). The rs152451-G/rs45551636-C and rs152451-G/rs45551636-T haplotypes were associated with an increased BC risk only in cases with a strong family history of BC (OR = 1.6 [CI 95% 1.0-2.5] p = 0.05 and OR = 3.7 [CI 95% 1.8-7.5] p < 0.001, respectively).

Conclusion

Our results suggest that PALB2 c.1676A > G and c.2993C > T play roles in BC risk in women with a strong family history of BC.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1033-3) contains supplementary material, which is available to authorized users.

Role of cytokine gene polymorphisms in gastric cancer risk in Chile

AIM

To assess the role of pro- and anti-inflammatory polymorphisms in gastric cancer susceptibility.

PATIENTS AND METHODS

We genotyped 12 polymorphisms in eight cytokine genes (Interleukin-1β -IL1B-, IL8, IL17A, IL17F, IL32, tumor necrosis factor-α -TNF-, IL1RN, IL10) in a case-control study of 147 patients with gastric cancer and 172 controls.

RESULTS

Single polymorphism analysis revealed an association between the IL10 -592C>A single nucleotide polymorphism and cases with moderately- or well-differentiated tumors [AA vs. GG, odds ratio (OR)=3.01; 95% confidence interval (CI)=1.08-8.50]. We further analyzed gene-gene interactions using a combined attribute network implemented in multifactor dimensionality reduction software. The analysis revealed an interaction between IL8 -251A>T and IL32 rs28372698 SNPs among cases with moderately- or well-differentiated tumors. Homozygosity for both IL8 -251T and IL32 T alleles increases the odds for developing gastric cancer up to 2.63-fold (OR=2.63; 95% CI=1.15-6.03). This association was higher compared to the homozygosity for the IL8-251 T allele alone (OR=1.11; 95% CI=0.51-2.43) or the IL32 T allele alone (OR=1.21; 95% CI=0.54-2.72).

CONCLUSION

These findings suggest that IL10 -592C>A increases the odds for developing gastric cancer. An interaction between IL8 -251A>T and IL32 rs28372698 SNPs is also proposed.

Association between TGFB3 and nonsyndromic cleft lip with or without cleft palate in a Chilean population

OBJECTIVE

To assess the possible association between TGFB3 allele variants and nonsyndromic cleft lip with or without cleft palate in a Chilean population.

DESIGN

In our study we used a case-parents trios design. The sample consisted of 150 unrelated trios ascertained through probands affected with nonsyndromic cleft lip with or without cleft palate. Three TGFB3 polymorphisms were analyzed (rs2268626, rs2268625, and rs3917201). An allele/haplotype transmission disequilibrium test was used to evaluate the possible genotype-phenotype association.

RESULTS

An overtransmission from parents to affected progeny was observed for the A allele of rs3917201 (p = .03) and for the rs2268625-rs3917201 A-A haplotype (p = .022). A defect of transmission of rs2268625-rs3917201 G-G haplotype (p = .022) was observed also.

CONCLUSIONS

Allelic and haplotypic associations implicate a possible role of TGFB3 in nonsyndromic cleft lip with or without cleft palate in the Chilean population. Additional studies are needed in order to elucidate the possible mechanisms that can explain the role of TGFB3 genetic variants in the condition.

Genetic variants in FGFR2 and MAP3K1 are associated with the risk of familial and early-onset breast cancer in a South-American population

Genome-Wide Association Studies have identified several loci associated with breast cancer (BC) in populations of different ethnic origins. One of the strongest associations was found in the FGFR2 gene, and MAP3K1 has been proposed as a low-penetrance BC risk factor. In this study, we evaluated the associations among FGFR2 SNPs rs2981582, rs2420946, and rs1219648; and MAP3K1 rs889312, with BC risk in 351 BRCA1/2-negative Chilean BC cases and 802 controls. All the SNPs studied were significantly associated with increased BC risk in familial BC and in non-familial early-onset BC, in a dose-dependent manner. Subjects with 3 risk alleles were at a significantly increased risk of BC compared with subjects with 0-2 risk alleles, in both familial BC and early-onset non-familial BC (OR = 1.47, 95 % CI 1.04-2.07, P = 0.026 and OR = 2.04 95 % CI 1.32-3.24, P < 0.001, respectively). In the haplotype analysis, the FGFR2 rs2981582 T / rs2420946 T / rs1219648 G haplotype (ht2) was associated with a significantly increased BC risk compared with the rs2981582 C / rs2420946 C / rs1219648 A haplotype in familial BC and in non-familial early-onset BC (OR = 1.32, 95 % CI 1.06-1.65, P = 0.012; OR = 1.46, 95 % CI 1.11-1.91, P = 0.004, respectively). When the FGFR2 ht2 and MAP3K1 rs889312 were evaluated as risk alleles, the risk of BC increased in a dose-dependent manner as the number of risk alleles increased (P trend <0.0001), indicating an additive effect. Nevertheless, there is no evidence of an interaction between FGFR2 ht2 and the MAP3K1 rs889312 C allele. These findings suggest that genetic variants in the FGFR2 and MAP3K1 genes may contribute to genetic susceptibility to BC.

Association between oral health and acute coronary syndrome in elderly people

With the aim of contributing information to help clarify the association between oral health, periodontal disease and ischemic cardiomyopathy, a comparative study was performed on hospitalized patients with and without acute coronary syndrome (ACS), evaluating atherogenic risk factors (ARF), level of oral hygiene and dental and periodontal health status. The study included patients in the coronary unit with ACS and patients in regular floor bed without evidence of cardiovascular pathology at Hospital Español, Buenos Aires, Argentina. The following ARFs were analyzed for all patients: hypertension, cholesterol, diabetes, obesity and smoking. The clinical dental examination included recording dental charts and variables related to oral hygiene, epidemiological indices and diagnosis of periodontal disease. The data collected were used to compare the ACS Group to the Control Group regarding prevalence of the ARFs and clinical dental variables studied. A total of 146 patients were studied: 81 male and 65 female, with average age 69.8 +/- 10.14 years. Prevalence of hypercholesterolemia was found to be significantly higher in patients in the ACS group than in the control group (p = 0.043). The other ARFs considered did not differ. The levels of oral hygiene were similar in both study groups. The prevalence of decayed and filled teeth was similar in both groups, although there was a significantly higher number of missing teeth in the ACS group (p < 0.001). Patients with ACS had more severe periodontal disease and higher levels of gingival inflammation than the control group (p < 0.001).

CONCLUSION

Oral health of patients with ACS was worse than oral health of patients without cardiovascular disease. The difference was shown by greater severity of periodontal disease in patients with ACS even though the level of oral hygiene was similar in both groups.

Association between bone morphogenetic protein 4 gene polymorphisms with nonsyndromic cleft lip with or without cleft palate in a chilean population

Nonsyndromic cleft lip with or without cleft palate (NSCLP) is one of the most common birth defects in humans with both genetic and environmental components involved in its expression. Experimental evidences have postulated that bone morphogenetic protein 4 gene (Bmp4) is involved in the etiology of cleft lip with or without cleft palate (CL/P) in mice. In our study we analyzed the association between BMP4 and NSCLP in a sample of 150 unrelated trios ascertained through affected probands. Three BMP4 polymorphisms were analyzed, two intronic (rs762642 and rs2855532) and rs1957860, located 5.7 kb upstream from BMP4. Transmission/disequilibrium tests were performed at the allele and haplotype levels. Our results did not detect preferential transmission for individual single-nucleotide polymorphisms. Significant transmission distortion was observed for haplotypes rs1957860-rs762642 (p = 0.018), especially for C-T (p = 0.015) and T-T (p = 0.018) which include the genomic region where the promoter and an enhancer of BMP4 are located. Thus, despite the positive association detected between these haplotypes and NSCLP they probably do not have a functional effect on BMP4 expression or protein activity but possibly reflect NSCLP susceptibility changes which are in linkage disequilibrium with these polymorphisms. The findings of our study support a role for BMP4 in NSCLP in the admixed Chilean population.

Variants in DNA double-strand break repair genes and risk of familial breast cancer in a South American population

The double-strand break (DSB) DNA repair pathway has been implicated in breast cancer (BC). RAD51 and its paralogs XRCC3 and RAD51D play an important role in the repair of DSB through homologous recombination (HR). Some polymorphisms including XRCC3-Thr241Met, RAD51-135G>C, and RAD51D-E233G have been found to confer increased BC susceptibility. In order to detect novel mutations that may contribute to BC susceptibility, 150 patients belonging to 150 Chilean BRCA1/2-negative families were screened for mutations in XRCC3. No mutations were detected in the XRCC3 gene. In addition, using a case-control design we studied the XRCC3-Thr241Met, and RAD51D-E233G polymorphisms in 267 BC cases and 500 controls to evaluate their possible association with BC susceptibility. The XRCC3 Met/Met genotype was associated with an increased BC risk (P = 0.003, OR = 2.44 [95%CI 1.34-4.43]). We did not find an association between E233G polymorphism and BC risk. We also analyzed the effect of combined genotypes among RAD51-135G>C, Thr241Met, and E233G polymorphisms on BC risk. No interaction was observed between Thr241Met and 135G>C. The combined genotype Thr/Met-E/G was associated with an increased BC risk among women who (a) have a family history of BC, (b) are BRCA1/2-negative, and (c) were <50 years at onset (n = 195) (P = 0.037, OR = 10.5 [95%CI 1.16-94.5]). Our results suggested that the variability of the DNA HR repair genes XRCC3 and RAD51D may play a role in BC risk, but this role may be underlined by a mutual interaction between these genes. These findings should be confirmed in other populations.

[Effects of periodontal therapy on markers of systemic inflammation in patients with coronary heart disease risk]

BACKGROUND

Studies investigating effects of periodontal treatment (PT) on markers of inflammation in healthy subjects show conflicting results. Few studies have investigated the effects of PT among subjects with coronary heart disease (CHD) risk factors.

AIM

To report the results of a pilot prospective study on the effects of periodontal treatment on markers of inflammation among subjects with CHD risk factors.

MATERIAL AND METHODS

Seventy three patients aged 53+/-6 years (25% males) with chronic periodontitis, dyslipidemia and other CHD risk factors were subjected to PT consisting on root planning and oral metronidazol and amoxicillin for 7 days. Periodontal clinical parameters, serum C-reactive protein (CRP), fibrinogen levels and erythrocyte sedimentation rate (ESR) were assessed before and at 6 weeks after PT. Polymorphisms at the ILlA-889 and IL1B+3954 genes were also genotyped.

RESULTS

After the treatment period, CRP levels significantly increased from 3.6+/-3.7 mg/ L to 5.4+/-5.7 mg/L (p =0.001). No significant changes were observed in fibrinogen levels and ESR. Higher post-treatment CRP levels were significantly associated with the composite polymorphic genotype at the ILlA-889 and IL1B+3954 genes (p =0.0001), and extensive periodontitis (p =0.005). Moderate alcohol consumption appeared as a protective factor for CRP elevation (p =0.029).

CONCLUSIONS

The increase of the CRP levels after PT in patients with CVD risk factors appeared associated with IL-1 gene polymorphisms and extensive periodontitis.

Association of common ATM variants with familial breast cancer in a South American population

Background

The ATM gene has been frequently involved in hereditary breast cancer as a low-penetrance susceptibility gene but evidence regarding the role of ATM as a breast cancer susceptibility gene has been contradictory.

Methods

In this study, a full mutation analysis of the ATM gene was carried out in patients from 137 Chilean breast cancer families, of which 126 were BRCA1/2 negatives and 11 BRCA1/2 positives. We further perform a case-control study between the subgroup of 126 cases BRCA1/2 negatives and 200 controls for the 5557G>A missense variant and the IVS38-8T>C and the IVS24-9delT polymorphisms.

Results

In the full mutation analysis we detected two missense variants and eight intronic polymorphisms. Carriers of the variant IVS24-9delT, or IVS38-8T>C, or 5557G>A showed an increase in breast cancer risk. The higher significance was observed in the carriers of IVS38-8T>C (OR = 3.09 [95%CI 1.11–8.59], p = 0.024). The IVS24-9 T/(-T), IVS38-8 T/C, 5557 G/A composite genotype confered a 3.19 fold increase in breast cancer risk (OR = 3.19 [95%CI 1.16–8.89], p = 0.021). The haplotype estimation suggested a strong linkage disequilibrium between the three markers (D' = 1). We detected only three haplotypes in the cases and control samples, some of these may be founder haplotypes in the Chilean population.

Conclusion

The IVS24-9 T/(-T), IVS38-8 T/C, 5557 G/A composite genotype alone or in combination with certain genetic background and/or environmental factors, could modify the cancer risk by increasing genetic inestability or by altering the effect of the normal DNA damage response.

RAD51 135G>C polymorphism and risk of familial breast cancer in a South American population

Several studies have reported that mutations in genes involved in maintenance of genome integrity may be responsible for increased cancer risk. Human RAD51, known to function in DNA repair, interacts with a number of proteins implicated in breast cancer (BC), including BRCA1 and BRCA2. Few studies have investigated the role of RAD51 gene variations in familial BC. To detect potential novel gene defects that may contribute to hereditary BC susceptibility, 143 patients belonging to 143 Chilean families tested for BRCA1 and BRCA2 mutations were screened for mutations in RAD51, using conformational sensitive gel electrophoresis (CSGE) and DNA sequencing. No mutations were detected in the exon or splice-boundary regions of the RAD51 gene in these families. The RAD51 135G>C polymorphism (c.-98G>C, rs1801320) was studied in a case-control design, to evaluate its possible association with BC susceptibility. The frequency of the RAD51 135C allele was established in 143 cases and 247 controls, using restriction fragment length polymorphism-polymerase chain reaction. RAD51 135C genotypes (G/C and C/C) were associated with an increased BC risk only among women with (a) a family history of BC, (b) BRCA1/2 negative (n = 131), and (c) age at onset <50 years (P = 0.020; OR = 2.17, 95% CI = 1.11-4.24). Thus, we propose that RAD51 135G>C polymorphism presents an increased risk of familial BC in women with age < 50 years at diagnosis, and this polymorphism may be a BC risk variant. This finding should be confirmed in other populations.

BRCA1 and BRCA2 mutations in a South American population

A sample of 64 high-risk breast and/or ovarian cancer families from Chile were screened for germline mutations in the coding sequences and exon-intron boundaries of BRCA1 (MIN no. 113705) and BRCA2 (MIN no. 600185) genes using conformation-sensitive gel electrophoresis, and the mutations found were confirmed with direct sequencing. Seven families (10.9%) were found to carry BRCA1 mutations and three families (4.7%) had BRCA2 mutations. Six different pathogenic mutations were detected in BRCA1, four that had been reported previously (c.187_188delAG; c.300T-->G, c.3450_3453delCAAG and IVS17-1G-->A) and two novel mutations (c.2605_2606delTT and c.4185_4188delCAAG). In BRCA2, we found three different pathogenic mutations, two previously described (c.6174delT and c.6503_6504delTT) and one novel mutation (c.5667delT). We also identified nine variants of unknown significance (five in BRCA1 and four in BRCA2). These findings indicate that the Chilean population has a heterogeneous spectrum of prevalent BRCA mutations. Given the results obtained in our study, the screening of the entire BRCA1 and BRCA2 coding regions is necessary for the molecular genetic testing of Chilean high-risk breast/ovarian cancer patients. To our knowledge, this is the first genetic study of BRCA gene mutations conducted in Chile. The Chilean population has a well-known admixed Amerindian-Caucasian ratio and, therefore, our findings are not only important per se, but they constitute the basis for improved and more specific genetic counselling, as well as to support for preventive campaigns geared toward the Chilean population.

[Possible association due to linkage disequilibrium of TGFA, RARA and BCL3 with nonsyndromic cleft lip with or without cleft palate in the Chilean population]

BACKGROUND

Nonsyndromic cleft lip/palate (NSCLP) is a congenital malformation with the characteristics of a complex genetic trait. Based on experimental evidences as well as on association and linkage studies candidate genes TGFA, RARA and BCL3 have been postulated as being involved in the genetic etiology of this pathology.

AIM

To test the possible association due to linkage disequilibrium between microsatellite markers located at less than 1cM from the three candidate genes and nonsyndromic cleft lip/palate using the case-parents trio design.

PATIENTS AND METHODS

The sample consisted of 58 case-parents trios. Two microsatellite markers, flanking each one of the candidate genes were analyzed by means of the polymerase chain reaction (PCR) with fluorescent labeled microsatellite markers. Electrophoresis of the PCR products was performed on a laser-fluorescent automatic DNA sequencer. Nonparametric ETDT was used to analyze the genotype data.

RESULTS

Significant linkage disequilibrium was detected between D2S443 (TGFA) and NSCLP. Significance was almost reached between D17S800 (RARA) and NSCLP. Alleles 239bp (D2S443) and 172bp (D17S800) showed significant preferential transmission from heterozygous parents to affected offspring. In the case of BCL3 both markers showed no significant results.

CONCLUSIONS

The results of the present study do not show clear evidence that TGFA or RARA could be involved in the genetic etiology of NSCLP. Even though the importance of retinoic acid in the development of the embryo is well documented the results obtained for RARA are difficult to analyze. In relation to the possible role of BCL3 in NSCLP, recent information postulates that other genes located in the same chromosome region could be involved in NSCLP.

Molecular analysis of the eighteen most frequent mutations in the BRCA1 gene in 63 Chilean breast cancer families

BRCA1 gene mutations account for nearly all families with multiple cases of both early onset breast and/or ovarian cancer and about 30% of hereditary breast cancer. Although to date more than 1,237 distinct mutations, polymorphisms, and variants have been described, several mutations have been found to be recurrent in this gene. We have analyzed 63 Chilean breast/ovarian cancer families for eighteen frequent BRCA1 mutations. The analysis of the five exons and two introns in which these mutations are located was made using mismatch PCR assay, ASO hybridization assay, restriction fragment analysis, allele specific PCR assay and direct sequentiation techniques. Two BRCA1 mutations (185delAG and C61G) and one variant of unknown significance (E1250K) were found in four of these families. Also, a new mutation (4185delCAAG) and one previously described polymorphism (E1038G) were found in two other families. The 185delAG was found in a 3.17% of the families and the others were present only in one of the families of this cohort. Therefore these mutations are not prominent in the Chilean population. The variant of unknown significance and the polymorphism detected could represent a founder effect of Spanish origin.

Association of interleukin-1 polymorphisms with aggressive periodontitis

BACKGROUND

Genetic polymorphisms for interleukin (IL)-1alpha and -1beta have been proposed as potential genetic markers for periodontal diseases. Since the prevalence of these polymorphisms could be race-related, and no data exist about the frequency of these polymorphisms in the Chilean population, the aim of the current study was to investigate the association of the interleukin-1 gene polymorphisms with aggressive periodontitis (AgP).

METHODS

Thirty-six patients with AgP, 75 healthy controls, and 75 subjects of unknown periodontal status (reference population) were genotyped for the IL-1A -889 and IL-1B +3954 loci, by polymerase chain reaction (PCR) amplification followed by restriction enzyme digestion and gel electrophoresis. Data were analyzed using the chi-square test, calculating odds ratios (OR) and confidence intervals (CI).

RESULTS

The prevalence of the positive composite IL-1 genotype was higher in patients (25%) than in healthy controls (12%), but the difference was not significant (P= 0.14). The IL-1B +3954 homozygous for allele 1 frequency was higher in controls than in patients suggesting a protective factor for AgP. The heterozygous for allele 2 of the IL- 1B showed a significant association with AgP (OR = 2.86, 95% CI 1.06 to 7.71, P= 0.030). No association was observed in localized AgP and generalized AgP between the extent of disease and the presence of the composite positive genotype. Because the number of smokers was too small in patients and in controls, no other analyses were performed.

CONCLUSION

The results of the present study support a positive association between AgP and the presence of the IL-1B +3954 allele 2 polymorphism.

Association of Interleukin-1 Polymorphisms With Periodontal Disease

BACKGROUND

Several studies have investigated genetic polymorphisms for cytokines as potential genetic markers for periodontitis. Some studies have found that interleukin (IL)-1A and IL-1B polymorphisms are associated with a higher severity of periodontitis, while others found no association. The aims of this study were to determine the prevalence of the IL-1A-889 and IL-1B+3954 (previously described as +3953) polymorphisms in Chileans and their association with periodontitis.

METHODS

Subjects aged 20 to 48 were selected from people requesting dental treatment at a public health center in Santiago, Chile. A case-control study of 330 cases of periodontitis patients and 101 healthy controls was performed. A full-mouth periodontal examination was performed on each subject and a structured questionnaire was conducted to determine smoking habits. Cases were categorized as having initial, moderate, or severe periodontitis according to the percentage of sites with clinical attachment loss > or =3 mm. Genomic DNA was analyzed for polymorphism in the IL-1A gene at site -889 and IL-1B gene at site +3954 by polymerase chain reaction (PCR) amplification followed by restriction enzyme digestion and gel electrophoresis. Data were analyzed by chi square test, analysis of variance (ANOVA), and by calculating odds ratio (OR) and 95% confidence intervals (CI).

RESULTS

Demographic and socio-economic characteristics of subjects were similar in cases and in controls. A higher frequency of heterozygous of the IL-1A-889 was found in cases than in controls, but the difference was not significant. The heterozygous of the IL-1B+3954 was significantly higher in cases than in controls and was associated with periodontitis (OR 3.12, 95% CI 1.59 to 6.09, P = 0.001). The homozygous for allele 1 of the IL-1B+3954 was a protective factor for periodontitis (OR 0.35, 95% CI 0.19 to 0.66, P = 0.001). The prevalence of positive genotype (at least one allele 2 present at each locus) was significantly higher in cases (26.06%) than in controls (9.9%) and was significantly associated with periodontitis (OR 3.21, 95% CI 1.60 to 6.44, P = 0.001), irrespective of the smoking status and periodontitis severity. Sensitivity of positive genotype was 26%, the specificity 90%, and the positive predictive value 89%.

CONCLUSION

Within the limits of this study, the results show that individuals carrying the positive genotype have significantly greater risk for developing periodontitis.